Das Wesentliche am Schuß: Brauchbare Treffer und richtiges Geschoß!

LM-Class Bullets

Very high BC bullets for windy long Ranges

History

Before You start her You may want to read History in Kummersdorf and Drive band bullets. These are my Fore thinkers. Thanks to the great Work, they did!

Ludwig Prandtl from Freising founded beginning 20^th century flow mechanics. Regarding congestion flows, his Findings are not noticed too much at Bullet tails. He taught in Göttingen in Deutschland (Germany)

Prandtls student in Göttingen, Theodore von Kármán / Hungary, in the 1920^ies first calculated a Minimum wave drag bullet tip.

The Hamburger Max Munk estimated the moment derivative for spitz Bullet tips. Later Beat Kneubuehl derived the maximum Bullet length of spin satbilized Bullets

Wolfgang Siegfried Haack expanded Kármáns Work. In 1941 in he presented a closed analytical Solution for the Minimum Wave drag projectile.

Lutz Möller erstes Kupfergeschoß

My first Bullet for the 8,5x64, not yet a real Drive band bullet, new and used.

Brass- and Copper-bullets from 5,6 mm to 14,5 mm from 2003 onwards

LM-119 and LM-71 in the Year 2008 | 9,5 and 5,6 mm

Fastest twist for highest BC

Lutz,

I can get a 1:4.7 Inch twist. What can you do with that for .308", .338", .375", and .510" calibers? That’s the fastest twist I can find a guy to do. That should open the door to some very high bc bullets.

Dave, Freitag, 1. Februar 2008 17:51

To stabilize the LM-Class very high BC bullets for long, wind Ranges use a 20 Caliber long Twist.

A Barrel's Twist angle is tan alpha = Pi / Twist length in Calibers

Lutz

This is an email I got from the guy who can do the 1:4.7 twist.

“Dave,

Fastest twist? I guess what I should've said is the fastest twist we've done to date has been a 1:4.7. We can do any twist you want for the most part. When the twist gets really fast or odd I should say what we have to do is to make a special tool. This is where a special twist charge comes in. You have to tell me what you are looking for and we then have to look at what it takes to do it. The rifling machine has the capabilities and is no problem but it comes down to making and working with the tooling. In each caliber you have to let me know what you want/need. The 1:4.7 twist we did on a .224 cal. barrel. The guy paid us for our time to make a special tool etc. and it all worked out fine.

Later, Frank”

I am guessing that tooling could be a limiting factor. His rifling machines are Pratt & Whitney machines that have been upgraded with cnc servos and controllers. It sounds like he wants to know the bullet dimensions before doing the twist. So I await your completion of the new bullet designs in the .375, .416 and .510 calibers. Once designing has been accomplished Frank can then make suggestions as to tooling costs and abilities.

Dave, Montag, 18. Februar 2008 17:16

Dave,

the .375 " LM-119 has the Land and Grove dimensions stated.

Lutz

Gain twist

I think he can do a gain twist too, this should alleviate some of the torsional forces placed upon the bands. I think though that the biggest benefiters of this fast of a twist would be the .375", .416" and .510" caliber, as the length to weight ratio would be more suitable for the case capacities used in such calibers. Do you agree?

LM: No, why should I?

I believe that your LM-105 is about max length to weight for case capacity used.

LM: It is near the Optimum, I say, but for other Reasons.

Freitag, 1. Februar 2008 18:08

5,6 mm LM-71 for the .22-250 from 2008

7 mm LM-84 for the 7 mm WSM from 2008

8 mm LM-102 for the 8x68Taras from 2008

8 mm LM-101 from 2007

Hurrah!

Minimum Drag LM-105 Long range Bullet

LM-105 won the 7^th Lapua Sniper Competition 2005

.375" Viking in 2008

9,5 mm (.375") LM-119 in 2008, replacing the Viking

LM-150 in 2008

"Viking" bullets

Guten Tag, Herr Möller!

Ich habe im Schule Deutsch gelernt, aber vielen Jahren später ist doch besser im Englisch zu schreiben, um präzise fragen zu stellen :)

I read with great interest about your .375" Viking project (Ich bin auch selbst Norwegischer Viking!). It is rather heavy artillery, but I couldn't stop thinking about what could be possible in lesser calibers with the same bullet profile.

Bullet weight is proportional to the third power of bullet diameter, and for a given bullet shape Greenhill's BC calculation is directly proportional to diameter. Using this to scale the .375 Viking gives a rough estimate of the following hypothetical bullets:

5.69 Viking MSG - 43 mm long, 93 grains, BC 0.94
6.18 Viking MSG - 47 mm long, 120 grains, BC 1.02
6.72 Viking MSG - 51 mm long, 154 grains, BC 1.11

These figures give very attractive wind drift and long range performance. Especially if it is possible to push them to 1000-1100
m/s using a reasonable size cartridge. Looking at the vom Hofe's and the 6.5x63 Messner and .22-06 Easling, it seems almost within reach!

The hard limit for your design, as I understand it, is the fastest twist available in barrels. For the Lothar Walther progressive twist barrels, I cannot find any information on their website but you state that 9° final twist angle is maximum. How does that hold as we move to smaller calibers? It translates to some seriously short twists, but implies that bullet shapes similar to the larger calibers can be stabilized?

Best regards, Tom K., Samstag, 2. Februar 2008 14:55

Hallo Tom,

Ein herzlichen Gruß nach Norwegen! Für bald 1'000 Jahre waren euere Schiffe die besten der Welt. Das will ich nicht vergessen! daran möchte ich mit dem Namen erinnern!

You push a leaned Door open. I work together with Noel Carlson (A Swedish origin, who lost an "s" in his Name in Amerietwa He builds special Cut heads for CNC-rifle-pull machines, that allow short and progressive Twist. From existing Demand the .375" Viking is Start on the big End. Currently I work on the small one and as well with a LM-71 to be used in a .22-250 Rem. or Ackley. That Cartridge allows small Systems. There are a few with electronic Ignition available, so we com from both Sides. We plan to successively add MSG and Gain twist barrels Calibers to the LM-Class.

The Viking is a specialty for extra long Ranges (2 - 3 km), when in the End Velocities are rather low. More common Ranges like 1'000 Yard = 0,914 km or so do not ask for this Extra feature, so the Viking tail may be omitted.

We keep in Touch and I will see, how the Community responds. For Cost- and Price-reasons I will use Brass, instead of special Copper, as Noel always reminds me to keep the Volume market for Sport shooters in Mind. For that Intention Brass fits the Optimization process better than Copper.

Regards, Lutz,

Futility

Lutz

I received the LM-105 bullet today. Its more impressive than in pictures. A beautiful piece of art with functionality!

Have you begun the design yet of the bullets I had asked about regarding the 1:4.7 fastest twist ratio I could find?

Dave, Donnerstag, 7. Februar 2008 05:42

Hallo Dave,

no I haven't. Currently my Workload is hefty. I will shortly add more to the LM-Class Bullets. Just 120 mm Twist length is rather short for 8,5 mm. Spin stabilized Bullets longer than 7 Calibers could be envisioned - needle sharp.

But I am afraid our Gain in wanted Slenderness will partly or even fully be wasted by Air friction. I do not know, how far we can push the Limit. If You want the longest 8,5 mm Bullet for 120 mm Twist length, I make you a Batch. Predictions will become vague in this unknown Area. If You like to risk a Custom made Barrel and a Batch of Bullets, I shall do it. But if the Results are not as fancy as they appear on Paper, do not blame me. I have to use a lot of Estimates an Guesses. After some Years meanwhile this works this well in known Territories. But if we set Sail to drive our Ships to New land to conquer the Unknown, Surprises are on Order. Not all may be pleasant, though.

You decide - and pay!

Lutz,

Lutz

I think that the 1:4.7 twist ratio would probably best be suited for the larger caliber such as the .375 and up.

LM: No. The shortest usable Twists are about 20 Calibers. Your Suggestion leaves that out.

I think anything below it has a diminishing returns aspect. Examining your LM-105 for the 338 I can’t see a longer bullet being made that would significantly outperform the LM-105 even with the fast twist rate.

As I said before, without mathematical equations or experiments just a visual estimation allows one to view a ratio between bullet length and bullet diameter. Somewhere it borders on the ridiculous as to how much bullet you want and what can be made to work. If it weren’t the case, people would be necking down 20 mm cases from the F-16 aircraft to 50 caliber and launching bullets at phenomenal speeds. As it is that is not the case as it crosses the diminishing returns barrier and thus is a waste of time and money. Although State Arms gun company a few years back were selling a necked down 50 bmg to .375 cal and launching solid bullets at close to 5000 fps. Al though this velocity was never reached with any of the guns others built on the same cartridge anything in the 300 grain area traveling at 4000 fps and faster is quite a feat. Barrel life however would be a huge dilemma.

I do however think that the twist offered can be applied to larger calibers up to and including the .50 BMG. I think that the starting point should be the .375. Yes I agree that at a certain design phase all bullets will encounter what you say about air friction. At what point do your bullets composition begin to transform due to heat at the leading edge?

LM: The LM-105 has seen 1'400 m/s and performed well!

This would be a limiting factor much like the SR-71 Blackbirds speed is limited by the material composition of the leading edges.

Of course I do not plan on even entertaining the idea of a Titanium tipped bullet. I am only talking 2500 yards trajectory. I am not too concerned with the actual flatness of the trajectory but more so the accuracy of the bullet. I do know that mass equals better predictability in bullet trajectory as it carries more of its energy downrange more efficiently.

When the Navy launches one of its 20 inch guns the projectile far from a perfect aerodynamic shape but its shear mass allows it to be accurate to within meters. While this accuracy isn’t acceptable in the rifle world, none of the rifles I know of are accurate to this degree over 20,000 yards. If one were to compare the two accuracy and extrapolate it out the smallest group I know of in 1000 yard competition is around 1.7 inches. This would be 34 inches at 20,000 using math only not real world data. We all know though that it is impossible for such a feat to be accomplished by such a small projectile and the mass of it.

Therefore I know that at extended ranges such as 1000 yards and beyond mass plays a more important role in trajectory predictability but the design of the bullet is where accuracy comes into play. This is where your bullets take over and finalize the design phase of this adventure.

I would still like to see your designs for bullets for the .375 cal and up with the twist ratio mentioned but with your keen sense of what would work and what would be an exercise in futility.

A .375" Bullet with 1 Turn in 4,7 Inches is a good Example for Futility

As you put it so eloquently in your last email “But if we set Sail to drive our Ships to New land to conquer the Unknown, Surprises are on Order.”.

One of our greatest abilities is to imagine the impossible, strive to meet it, take comfort knowing we tried, and reflect on the lessons we learned but most of all along this journey take from it what advances us.

Thank you, Your friend; Dave Boday, Freitag, 8. Februar 2008 18:14

Cheap Barnes Band Manufacturing

by contoured Cutter

Lutz

I apologize to interrupt your concert.

I visited Barnes website. They make a very crude version of a banded bullet.

LM: See not exactly Barnes "banded" 12,7 mm Bullets, but some from Norway and other Places, used Subsonic

I also received their DVD with some bullets I purchased for a special project. In the video they show a lathe that has live tooling which has a cutter head ground specifically for the grooves to be cut in the shank. The shaped cutter revolves and so does the bullet and the two meet and remove material. This leaves some horrible tooling marks in the band area but doubt if it contributes to anything.

LM: Thank You Dave,to mention that. This explains a lot! To use a contoured Cutter (I would call that a "Form steel", but that probably is not the correct technical English Expression) is a very cheap Method to create a Contour in a turned Object like a Bullet. One may safely use it for the Extractor groove in a Cartridge case, that demands no stringent Accuracy and is happy with ± 0,1 mm, but with a Bullet You want to repeat Accuracy over a large Series an Order of Magnitude lower. So in my not so humble Opinion, to use contoured Cutters to create Groves it inappropriate. While the Barnes Customers will enjoy the inherent Cost savings, the must bare the equally inherent lower Quality as well. While Accuracy is no Point, when You shoot a Buffalo off Hand in 50 m Distance it will be so, when You intend use the same Rifle for Antelope an Gazella in 200 mm Distance or more, as I will do in May with the 9,3 mm KJG in South Africa.

After examining your bullet closely there can been seen only one tooling path and a cut-off. Are your bullets completely turned with no other machining steps?

LM: Well Dave, have Look into the Factory. The Process depends on the certain Bullet and may vary.

A cut 8x68S Case empty and with a 8 mm KJG with aerodynamic black Tip

Obviously the Copper hunt Bullets with a hollow Point must be drilled as well, the create the hollow Cavity in Front.

8x68S-Taras

LM: The 8x68S-Taras will be drilled from the Back (of the Bullet, not the Brass rod in the CNC-Lathe). The Requirement for that Bullet was to use an exiting long Twist Barrel (280 mm in 8 mm Caliber) and create the best Long range Bullet possible at the very Edge (of Stability) Now this is it. It remains to be seen, whether I designed over the Edge and Taras it will tumble, like the one below.

Tumbling 8,5 mm MSG in 100 m from a TRG-42 with too shallow Twist for that bullet

Old 8,5 mm MSG in the Middle, too long to a standard TRG-42

LM: Some Bullets are turned with one Tool and from one Side, others with multiple Tools from more Sides. I can desgn for a Process, o a Process has to adapt a Design. With all that many Bullets, no single Answer is possible and I will not outline the nitty gritty Details. I assure You, we take the necessary Steps and Tools to solve the given Order.

What tolerances do you keep on these bullets. To me a unilateral tolerance would seem to be the best to use as the shank diameter if made to small would allow gases to escape. This small void would allow hot gases to pass buy and create a super heated area and melt the surrounding bullet and possibly barrel.

LM: No. The Bands with the larger Diameter seal the Barrel, not the smaller Shank diameter, having the Band thickness spacing to the Groves. Including Tolerances Bands are dimensioned slightly over Bore and the Shanks slightly under Grove.

A bilateral tolerance would mean that the consistency you talk about as far as the extreme spread or standard deviation would suffer greatly if the bullets were to extreme from one side of the tolerance to the other.

The machines you use must be of the highest quality to hold such tight tolerances. In the English world I would suspect that +.0003/.0000 would be along the lines of what turned bullets would or should be held to? Did you design or equip an old automatic screw machine with cnc servos or is it say; a high quality Swiss made cnc lathe that you use.

LM: The Truth is a variety of German Machines have been and can be used to turn Bullets, including old Cam-driven Lathes. These have been around for Decades and it's a Shame low engrave Force and low Friction drive Band Bullets have not been made by our Fathers, as that would have been possible. These old machines leave the Factories by and by and modern CNC-Lathers replace them. Our Oldest Machine is an almost 20 year old Gildemeister, that has been rebuilt once, and the newest a Citizen Boley 42, where German Machinery and Japanese Electronics meet in one. Nothing against Swiss Machinery, but we can to that well here in Germany.

What kind of quality assurance do you use, ISO 9002? Is each bullet inspected and if so how? What singles out a bullet that is bad, weight, length, diameter, machining marks etc?

LM: We use a Sample Plan to inspect Dimensions and Appearance.

Left: All right .408 MSG | right: Wrong Bullet.

LM: This wrong Bullet slipped Inspection and was actually shipped to an Italian Customer. He moaned. I published a Recall on my Website and on Snipers Hide. He sent the faulty bullets in and I replaced them. This is the rare Exception, but when it happens it will also in the Future be handled like that.

I ask so many questions because I think that your bullets are superior in every way. It is hard to convince a certain group of people that switching to these style bullets may be the advantage they are looking for.

LM: Look close to the Copper hunt Bullets with the black Tip.

10 x Enlagerement

20 x Enlagerement

I ask these questions so I may give educated answers to these people and hopefully persuade them to try your bullets. Dave Wilson has had correspondence with you and he is one such person in the group that I belong to. These people are always looking for an advantage or the perfect set-up.

They are skeptical of lathe turned bullets because of all the hype around Lost River bullets. Many of these people in my group have been scammed by the LRB dream bullets.

LM: What was the Scam then?

Your bullets are not the same, but one thing remains the same and that is lathe turned which is a key factor in keeping interest up and alive with these folks. Knowing how you make them, what type of tolerances you hold, what kind of machines you use can all be used to build a better case for your bullets.

Your friend, Dave, Sonntag, 10. Februar 2008 07:49

Dave,

I will not publish too many details. But look. Anyone can stuff my Bullets into Rifle and shoot the recommended Load right out of the Press (no Load development at all) with vulume metered Powder (not weighed) like that:

3 Times 8,5 mm KJG in 100 m

Next not developed Load load, but with weighed Powder charge within 0,01 g Deviation and a good Man at the Trigger shoots like that:

Four Times 8,5 mm KJG lang in 100 m from the Design study "Weltrekordgewehr" in .338" LM

Marin Enders willingly killed Flea on a 100 m Target with his Tikka T3 in .300" WM

But regular and cheap Hunting Rifles like this CZ in .30-06 can do that as well

3 x 7,62 mm KJG old in 100 m

Now comes a fantastic one. M. K. shoots a Sauer 202 in 8x68S, like the one below, but less the BiPod:

Another Sauer-202, here from Mark / Worcestershire in 7x64 in Scotland

M. K. has a good shooting rifle and is quite content with it and himself using it. He bagged quite some Game last Year. Then He had the Idea to check how well the Rifle would hit in 300 m. Out on his Hunting ground he placed a Target in 300 m and shot twice:

Two times 8x68S with Copper hunt bullet out of a Sauer 202 in 300 m: Two Shots → On Hole (in 300 m)

This is the Best I have seen so far.

While it's easy to shoot worse, to shoot better will become a Problem. Apparently my Bullets are not a limiting Factor for Accuracy. The Shooter and the Wind play a much bigger Role. There are enough good Rifles out there.

Bussiness Environment

The Majority of my Bullets are for Hunters, but You can win a Match with them any Day, if You will. The few "MSG" Sport bullets (Messingsportgeschoß = Brass sport bullet) make no big Difference to the Volume. The Bullet volume make no big Difference to the Machine shop, as most of the Time other Parts are made there. I say that only to give an Idea, whether Availability is at Risk, if only few People by. No it's not. Sure I would like larger Volume and use the Economics of Scale, but I can sustain low Volume indefinitely. I may not always have enough Time to create new Custom bullets designs, as that takes quite some Time. But just ask and You shall receive an Answer.

Outlook

Together with Noel Carson for Barrels and some further help from Jeff Siewert / Arrowtech, Sven Eric Johannsson / Nordicballistic and Eurenco / Bofors, Hartmut Brömel / Quickload, I shall extend the LM-Class bullet series with Optimization on long Range and the Possibility to use Economics of Scale, once Demand ramps up. Noel Carlson has the Ability to single point cut Progressive twist rifles into Barrel and to adjust the Land width accordingly. When designing for a specific Cartridge we can adopt the Pressure decay with the Twist gain to create a best solution. These Refinements are not possible with other, cheaper Barrel production processes like Hammering, button rifling, Multi-point-cutting.

The LM-Class bullets will be made from Brass, not Copper, as Varieties exist that are best suited for precise and fast Machining, as is needed for Accuracy an Economy.

Requirements

Achtung! They all needs a certain minimal Muzzle velocity to fly stable from a determined Gain twist barrel with an integrated hdp-gas-exhaust, a. k. a. Recoil brake or Muzzle brake. I make those. This means, the Bullets will not fly stable from smaller Cartridges, yielding less Velocity, but from bigger ones. Bigger would not be better, as internal ballistic Efficiency would drop and too long Barrels would be needed.

Adams Tail

That drag minimizing Tail introduced Mac. C. Adams in Langley, November 1951. M. A. Ramaswamy and S. Viswanathan optimized it December 1975 in Bangalore.

Unfortunately the "Adams tail" has a Drawback. But that can be taken Care of. Highly energetic expanding Flow at the Muzzle disturbs sharp angled Bottoms, introduce annoying Dispersion.

One Adams Tail stands out

Adams Tails on Haack Bullets

.50" Cal. hdp-Brake

Sleeved Brake

The raw Barrel weighs about 8,9 kg. As with 15 g Propellant and 64,8 g Bullet mass, the Gas dynamic brake effect can only be minor, one has to resort to a heavy Barrel and Rifle. Just 23 % Powder Mass cannot brake 100% Bullet Mass effectively, no Matter how well designed the Brake is (and mine is!). The .50" BMG Catridge is an annoying Monster, that needs some Taming, to become a pleasant Toy for Weekends on the Range or other Purposes. Let Lothar Walther add the integrated .50 hdp-Brake, or if for Simplicity, You buy a Blank ex Stock, let Your Machine shop drill first the Brake Holes, then ream the 13,5 mm for 80 mm, and then on the Outside add a 30 mm Thread, or something else You like (maybe an Inch whatever Thread, if You dare). Cover the Barrel with a Tube some 100 mm or 4 Inch (10,16 mm) and depending on Material (Steel, Aluminium, Carbon Fibre) some 2 - 3 mm thick.

Fancy Stuff: Carbon Fiber and Aluminum

Close the Tube in the Front with a Plate with the Thread, to attach it firmly. A light Carbon fiber enclosure is a good Ideas, as it easily moves with Barrel vibration and the Thread will not rattle on these low Mass forces. Metal is heavier, but sturdier. not Not to burn away, Carbon fiber enclosures need around the Brake internally a Metal shield.

The Brake enclosures Back cannot be attached with a Thread to allow thermal expansion. So the Back plate must be decoupled with a Plastic bushing (Polyamide, Nylon POM, or alike). Why all that? The 15 g Powder are more than a normal Shooter can stand. Any effective gas dynamic Brake aggravates Blast and Nose. To still use the Brakes Recoil reduction, though not too important compared to Rifle weight, I encapsulate the Brake in this hollow Sleeve. The Encapsulated Volume (the bigger the better) allows the Gases to leave the Barrel through the hdp-muzzle brake, but bar any Pressure Waves toward the Shooter. Voilá, there You have it: A pleasant Brake, unheard off Yet. The voluminous encapsulated gas dynamic Brake will eat (some) Recoil, Flash, and bar the Excessive Noise, the Brake usually generates, to reach the Shooters Ear. Carbon Fiber stuff is expensive, I know, but currently the best Solution to the Problem. Aluminum and Steal, if carefully dimensioned, work too. Grate Care has to be undertaken to fasten Front and Back, so they cannot rattle under great Forces normal to the Barrel but still move along the Barrel under thermal Expansion.

Any good Action can be used to build a .50 BMG with this Barrel an Bullet. The Stock must provide enough Room for the big voluminous Brake Encapsulation, tat I freely dub "Sleeved Brake", as it sleeves the Brake fully and the Barrel partly. The Rifle will look rather awkward, when upright like an Oven chimney. Let You fellow Shooters an the Range smile or laugh. Remember: The one, who smile last, smiles best. This exactly will happen, when You command Your braked and sleeved Barrel "Not-so-Loudenboomer". If heavy enough, You will be able to shoot the Rifle will Trust and after a While even with Pleasure and only then with Success. The sleeved Brake encapsulates the normally annoying Blast front, kicking You in the Face. Folks without this Feature will most often develop a Headache after 20 Shots and hence cannot practice, as needed to perform well. To moderate a .50 BMG Rifle is in my not so humble Opinion the only Road to Success. Too may Folks, looking for the Big one, cannot handle it well, because they flinch. I cannot blame them. Raw Fifty is tough Stuff. A Fifty with an open Muzzle brake is more most People can handle. Do not be tough, be smart, moderate the Monster in the above outlines Way and You can shoot it without Angst.

Dave,

I hope Your Question are answered. If not, You have bad Luck, as I move to the Café now, as a Sunday afternoon should see something else then Work. But You may always ask again.

Regards Lutz,

Chuckle for Futility

Lutz,

I read your article Cheap Barnes Band Manufacturing on banded Bullets. You have a good sense of humor,

”A .375" Bullet with 1 Turn in 4,7 Inches is a good Example for Futility”

I got a good chuckle out of that comment. I do not belong to Snipers Hide or any Sniper type forum. They are all a bunch of nut jobs, crazies, some are good, but way to much information is covered in those forums that the regular citizen should never be privileged to. In fact I was banned from Snipers Hide for voicing my opinion on a certain subject of how bullets react when shooting through glass. I said that the civilian citizen which has no affiliation with any government agency nor is required to perform such shooting tasks should be allowed to review such information. It is dangerous in the hands of the wrong people. They (Snipers Hide) referred me to freedom of speech, I referred them to militants.

I belong to forums where 1000 yard competition shooting is discussed and hunting long range out to and beyond 2100 yards.

Dave, Sonntag, 10. Februar 2008 17:58

Oh Dave,

then You should hate Panzerglas Glass braker. I have been asked several Times by the Police or alike Agencies to develop special Bullets, like a Fragmenter "Zerleger" or a Glass braker and made them all public, in including subsonic Stuff for the .300" Whisper with Silencers that are seriously silent and dangerous, though mostly used for confined Game.

Regards Lutz,

Shock wave angle

Hallo again Lutz.

What is the importance of the shockwave angle at the nose?

Click to enlarge

Ernst Mach ~ 1900

LM: Well Dave, to understand Shock waves You must familiarize with the Supersonic flow work of Ernst Mach. He explains that all. In short the Bullet speed and the Sound speed in Air form the Angle. I cannot change that by Bullet design.

If some bands were added to the front of the nose, would they also perform the same as the bands on the shank of the bullet?

LM: You want attached Streamlines on the Nose, not disturb them. There is absolutely no Need to introduce Micro turbulences on the Nose.

Would this decrease the angle of the shockwave riding on the nose of the bullet?

LM: No.

What effects would this have on flight?

LM: Increase Drag and decrease Stability.

I am becoming every interested in the design of the bullets and how to improve on them if possible.I have been studying the flight characteristics of air craft that perform in the supersonic range. Their leading edges and overall design could be utilized on some of the larger bullets.

LM: Yes.

I have ordered Cosmos software and have begun drawing some bullets shapes in Solidworks. When I receive the COSMOS software would you kindly help me set-it up for the same purpose you have yours set-up for?

LM: Oh, You really o for it. Cosmos is pretty intuitive to use. You will handle that.

Your friend, Dave, Sonntag, 17. Februar 2008 20:50

.300 RUM very high BC Bullet

Hello Lutz,

I currently shoot a .300 RUM with meplat pointed 15,5 g (240 grain) MK's (real BC .720) at 914 m/s (3,000 fps). I am looking at getting a spare barrel for the rifle later in the year......What would be the highest BC bullet you could make for a 30" long 1-7" twist barrel? Also roughly what would each bullet cost?

Thank you very much, Chris, Sonntag, 17. Februar 2008 22:16

Hallo Chris,

very high BC Bullets for windy long Ranges require 20 Calibers Twist length. For 7,82 mm Grove that are 156 mm. So Your 1:7" 178 mm Twist length is too long to fire a best Bullet. For a .30" Bore Rifle an LM-Class Performer would slightly surpass the LM-102. You waist Money to go for a longer Twist in a new Barrel.

Commercial Information follows.

Regards, Lutz Moeller, 17^th February

.30 cal with 1:7 Inch Twist

LM-103

Chris, here is Your .30 cal with 1:7 Inch Twist Bullet:

LM-103, 50 mm long, 12,7 g (195 Grains) heavy, BC 1,024 for 103 mm .300 RUM Cartridge with 1:7" Twist

103 mm long .300 RUM Cartridge with LM-103

5,95 g Alliant Reloder bring 970 m/s Velocity from 762 mm Barrel and 84,6 cm Wind drift at 4 m/s Cross wind in 1000 m within specified Pressure limits. Is that, what You want?

Lutz, 18^th February 2008,

LM-class bullets for .300 WM and TRG42

Mr. MOELLER,

What do you recommend as LM-class bullet for target shooting at 600 meters with TRG42 cal .300 winch magnum, standard TRG barrel with 1 in 11 inch right-hand twist rate, 690 mm and muzzle brake. Actually, I load lapua cases with 74 grains Vihtavuori N 165 and bullet sierra 2220 180 grains moly, seating depth 0.010 inch of the rifling and speed 2870fps.

I suppose that the 7.62mm KSG Sergey 300 WM is considered as LM-class bullet and that a 1 in 11 inch twist
is not adapted for this bullet ?

Thank you, JC MEUNIER, Belgium, Donnerstag, 1. Mai 2008 17:07

Dear Jean Claude,

the 7,62 mm Sergey was made for existing Rifles with Standard Twist in .300“ WM. It is not considered as an LM-Class Bullet, but You may shoot it from from 280 mm Twist.

If You want a 7,62 mm LM-Class Bullet, than You MUST use less than 156 mm Twist – not 280!

Lutz,

LM-Class Bullet in .416"

Ok Lutz.

I will order .416" barrels during this week. The reamer will be a bit difficult, because the design is proprietary, so what I plan to do is to take the full length die and make a cast of the die chamber, then adjust chamber neck to give right expansion room. This way, I hope, I will get a good chamber/die similarity. Is there a way to predict the shape length of the bullet to get the reamer made to fit right away, or maybe I need to order a .416f freebore reamer as well to adjust this later. I figure you bullets will be longer than .416 barrett`s. Anyway if you want to talk on the telephone, but for now, I think I can explain myself much better in writing than in talking ;-)

Anders, Montag, 18. Februar 2008 17:26

Anders,

to my best Knowledge Åke Nilsson / Norma / Åmotfors / Sweden first invented the .416"-.50"BMG before he discussed it with Barrett. Then Barrett just took it. The design project was there under Pete Forras / Barret until he left Barrett, when the .416"Barret was delivered. So Barrett does probably know not so much about it now. Norma has a Pressure barrel for it. So for Load development I would look to contact Åke.

As usual I will specify the Bullet together with a Chamber. As not Standard exits, I will set one for my .416" LM-Class very high BC Bullet for windy long Ranges. Bore Ø will be 10.37 mm (.408") and Groove Ø 10,57 mm (.416).

You should not worry about specifics but wait for me to show the Design, when I'm ready. That may well be after my Vacation from End February to mid March in the Caribic.

Lutz

LM-Class Bullet in .458"

Hi,

i was reading on your website, and read that you made custom solid, turned, VLD bullets. Is this true?

LM: Yes!

If so, i am looking to make a long range .458 cal round. with bullets up to 800gr.

LM: Too heavy for the Caliber!

What is the highest BC you could get?

LM: Somewhere below the LM-150 with 1,74.

The overall lenght isn't a problem as i have to get a custom action anyhow. I can get a barrel with a 1:8 twist. Is this fast enough?

LM: The very high BC bullets need a Twist of about 20 Calibers long, that multiply in Your .458" Caliber to 9.16 Inches for one Turn. Who would supply the Barrels?

Also, do you have a link to a page (in english, my german isn't the best. Getting better with a course though) that explains all this in laymens terms?

LM: Not really. But look here in LM-Class Bullets

I am called a genius by my friends, but i cant even understand what the basics are. thanks, Gavin, Mittwoch, 30. April 2008 04:50

LM: How nice Friends You have!