Lutz Möller LM-84

Very high BC Bullet for windy long Ranges

siehe auch LM7 / 2016

7 mm WSM with LM-84 with 84 mm overall Length for small Systems with 762 mm Barrel

LM-84 47 mm long, 10,43 g heavy, BC1000 0,973, for 165 mm Gain twist barrel with hdp-Recoil brake

Siehe auch LM7 für die 7 mm Rem Mag für die Merkel K3 Tar GT

Mass [g] Density
[%]
Pressure [bar] Burn rate
[%]
V0
[m/s]
Remark
highest @ muzzle
4,41 100,1 4'437 696 100,0 992
4,50 103,8 4'152 669 100,0 980
4,15 95,70 4'464 656 99,99 972
4,45 105,1 4'303 687 99,90 979
4,42 102,5 4'446 706 99,99 998
4,45 98,90 4'421 700 100,0 998
Path sighted in at 234 m for 271 m ± 5 cm Range
0 50 100 150 200 250 300
1'000 983 966 989 915 899 883
-5,0 +0,9 +4,5 +4,9 +2,9 -1,8 -9,5
0 0,2 0,8 1,7 3,0 4,5 6,5
to 1200 m
0 200 400 600 800 1.000 1.200
1'000 932 867 805 737 671 609
-5 +102 +165 +174 +124 X -211
0 3 12 28 51 85 130

Warning: Smaller Casses (like the 7 mm RSAUM) than the 7 mm WSM and shorter Barrels fail to obtain the necesary Speed to stabilize this Bullet. It cannot be shot any slower! Faster is fine.

Barrel

Six 2,80 mm wide Grooves and corresponding Lands are to be used. Grouve Diameter shall be 7,21 mm. The Bore is slightly smaller than the "usual imperial" 7 mm Bore, that typically is 7,04 mm. Also the Groves are tighter than the "usual German" 7,24 mm Grove Ø. As the Barrels need to be custom tailored anyway, this should be noticed.

Twist

Use preferably a progessive Twist starting from 40 Caliber length at the Chamber to 20 Caliber at the Muzzle or 280 mm to 140 mm, or 4,5°  to 9° Angle. Is a straight Twist is used, the shorter of the two mußt be used. If Problems with Drive band shear off should arise, ´those caoul be widened to accomodate. Please not, this would rise Pressure and Fruction, so while a staig Twist is possible too, it performs lower and heast more, so is less desirable

Throat

The Standard 7 mm WSM Throat suits the LM-84 not, as the Leade is to long and wide. All other Dimensions are fine. The LM-84 Throat is 2° full cone angle, as Europeans say or 1° half Angle from the Cone surface to the Rotation axis. Coming from the foremost Neck dimension 8,03 mm Ø at 53,59 mm Length from the Chamber Bottom, out of which the Case bottom sticks 0,1 mm out, a 90° Cone (full Angle) for 0,36 mm follows. There the 2° Throat starts at 7,32 mm Ø an then, including the first Cone, reaches for 9,52 mm to the 7 mm Bore.

While a standard 7 mm WSM Reamer may be used for the Case, either a separate 2° included Angle Throat reamer shall be used, or a Custom reamer for the 7 mm WSM be employed.

7 mm WSM Cases may be neck turned. If so above Dimensions bust be accommodated to keep the 2° Throat at the same location with Respect to the Case, but for the LM-84 this extra Effort is not really necessary. See below, how the first two Drive bands fit in the 2° Throat:

They are dimensioned to fit with +0,01 mm Space Surface to Surface or 0,02 mm in Diameter. A Zero Tolerance cannot be designed, as all mechanical Parts are made with Tolerances, the LM-84 not excepted.

One Millimeter moved a 2° Cone changes 0,035 mm Diameter (above is 10(!) mm long). So to adjust for 0,02 mm Diameter either the Throat or the Bullet have to be moved 0,02/0,035 = 0,57 mm or roughly 0,6 mm. That is more than wanted, as the overall Cartridge length is fixed to 84 mm, hence the Name, so some Gap might persist. This Gap will allow to unchamber unfired Rounds, if for some Reason, the intended Shot cannot be fired. So a basic Safety requirement for Shooting ranges is met.

MR. MOELLER.

I am a custom riflemaker out of California U.S.A.. I read about your LM-105 and LM-84, quite impressive. Would you please let me know your current prices pre 100 for both lm105 & lm84 and also how longwould it take to deliver them to me, [...]

LM:  Via Email!

My second question is about throat lead angle on LM-84, you stated 2 degree. Is it 2deg. per side or 2 deg. included angle?

LM: The 2° are included Angle, or 1° per Side. Please read Throat.

LOOKING FORWARD HEARING FROM YOU.

RESPECTFULLY, RAY RIGANIAN, Sonntag, 25. Mai 2008 02:07

Aerodynamics

LM-84 950 m/s Pressure, click to enlarge

LM-84 950 m/s Pressure Iso-lines, click to enlarge

LM-84 950 m/s dynamic Pressure contour, click to enlarge

LM-84 950 m/s dynamic Pressure Iso-lines, click to enlarge

LM-84 950 m/s Velocity contour, click to enlarge

LM-84 950 m/s Velocity Iso-lines, click to enlarge

Stability

Estimated Drag, BC and Gyroscopic Stability at Standard ICAO Sea Level Conditions
 -----------------------------------------------------------------------------------
  Möller LM-84 Cal. 7.210 mm, 10.34 g
  Ballistic Coefficient Calculated for Drag Function G1
 -----------------------------------------------------------------------------------
      Velocity       Drag Coefficient       RPM and Stability      maximum Twist-
                      Factor of Form        at a Twistlength         lenght
                         and B.C.1             of 22,9 Cal.          for s = 1.3
   Mach  m/s   fps    Cw      i   B.C.1       RPM        s        Cal.   in.    mm
 -----------------------------------------------------------------------------------
  0,441  150   492  0,072  0,353  0,802      54545      0,92      19,2   5,5   139
  0,514  175   574  0,070  0,352  0,805      63636      0,91      19,1   5,4   138
  0,588  200   656  0,069  0,347  0,816      72727      0,89      18,9   5,4   136
  0,661  225   738  0,069  0,334  0,848      81818      0,86      18,6   5,3   134
  0,735  250   820  0,069  0,308  0,919      90909      0,82      18,2   5,2   131
  0,808  275   902  0,069  0,270  1,049     100000      0,76      17,5   5,0   126
  0,882  300   984  0,073  0,230  1,230     109091      0,66      16,3   4,6   117
  0,955  325  1066  0,108  0,264  1,072     118182      0,44      13,3   3,8    96
  1,000  340  1116  0,228  0,482  0,586     123743      0,51      14,3   4,1   103
  1,102  375  1230  0,195  0,336  0,841     136364      0,59      15,4   4,4   111
  1,175  400  1312  0,244  0,392  0,721     145455      0,69      16,7   4,7   120
  1,763  600  1969  0,211  0,342  0,828     218182      1,10      21,0   6,0   152
  2,351  800  2625  0,174  0,320  0,883     290909      1,25      22,4   6,4   162
  2,939 1000  3281  0,148  0,291  0,973     363636      1,33      23,2   6,6   167
  3,526 1200  3937  0,127  0,256  1,105     436364      1,38      23,6   6,7   170
  4,114 1400  4593  0,111  0,226  1,253     509091      1,42      23,9   6,8   172
  4,702 1600  5249  0,099  0,201  1,410     581818      1,45      24,2   6,9   174
  5,290 1800  5906  0,089  0,180  1,569     654545      1,48      24,4   6,9   176
 -----------------------------------------------------------------------------------

Achtung! The LM-84 needs at least 975 Muzzle velocity to fly stable from a 165 mm Gain twist barrel with an integrated hdp-exhaust, a. k. a. Recoil brake or Muzzle brake. Noel Carlson will supply such. This Note means, it 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.

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 disturb sharp angled Bottoms, introduce annoying Dispersion.

More, see Muzzle flash

The integrated hdp-Exhaust accommodates the High speed minimum drag Adams tail at the Muzzle. The Exhaust may be sleeved with a closed Volume to constitute a recoil and flash absorbing Silencer.

One may ask,  why I design so many different shaped Projectiles. Aren't there optimal Solutions? Yes, there are, but the Conditions determine the Optimum. Different Conditions yield different Optimization shapes. This LM-84 is optimized for to deliver 975 m/s Muzzle velocity from a 7 mm WSM Cartridge out of a 70 cm Barrel. Other Projectiles exit for other Conditions. The Barrel shall have a progressive, or gain Twist with final 165 mm Twist length. This slow Twist start is meant to ease Drive bands requirements to reduce Engraving forces and Friction, but still withstand the Shear forces for such high Spinning. The ~ 354'278 Revolutions / Minute are fast indeed. The LM-84 will handle that well.

Lutz Moeller, 4th February 2008

LM-84 Barrels

hello lutz

and thanks for information. i know that erkki mäkinen, but is it something else possible place to get barrels, and how can made right kind of progressive barrel for special order? (walther, border, krieger, etc). I have seen these mäkinen maded barrels, and quality doesnt make me "happy",

-sauli- Mittwoch, 2. April 2008 08:00

Hallo Sauli,

Border / UK and Gruenig & Elmiger / Switzerland cannot make Gain Twist, unless they commit large Investments on the Machine + Tooling. They definitely make very good Barrels, expensive though. Walther, is a different Story. While thy have also Tool costs for custom Twists, their production is cheaper. Usually Walther is happy to make 10 custom barrels or more and Prices then become moderate. I just get a Group for .338" LM Gain twist barrels together.

If You find some Friends to join for a 7 mm LM-84 Project, maybe worldwide, we can do it easily. For just one Barrel You must have deep Pockets, Walther quoted 4 Months lead time for such a Project. But remember the Bisley ban!

Regards Lutz

Exploding Birds

Hi Lutz

I already have order inside on Border to "8.5"/7mm caliber barrel, because i am calculated also solid bullets and mean to tested them, when everything is ready. Those your bullet are very interesting.

I have used free software "WIN GYRO" calculated barrel twists and create right kind of bullet wich was be enough good stability factors and so good ballistic coefficient as possible for my knowledge. Material i have mean to bearing bronze, which is heavier as pure copper. All that basis Berger 10,9 and 11,7 g VLD bullets, which are quite good long range bullets. Some impulses has get also .408 Chey Tac bullet also.

7 mm Geschosse in der 7 mm WSM

My target in this is, made bullet which was be enough accuracy and good ballistic coefficient bullet to long range shooting (BC +.700) and bird hunting for my own needs.

Beute: Black Grouse, Birkhuhn

Black Grouses hunting by rifle from the top of trees in autumn after when first ones frost weathers are arrived. Sometimes shooting trips can be quite long.

Waldrand in 500 m

Tausendmeterziel

It is difficult when is small target. Immediately killing area is about 5cm. Last autumn longest trip was 450 meters, where i got
Black Grouse.

For few years in dry to found right kind of ready factory bullet, but without results. Your LM-84 is most near right kind of my needs what i have found. Some interested i have found but all have being hollow point bullet and it do not work, when asking bird hunting: It explode bird !

Explosion

These reasons to i have planning my own solid bullet project also for few months. Me and couple of my friend, we have private place to shoot, tested and training always 0 to 1200 meters. Changes which is quite less persons so good as we.

-Sauli-, Donnerstag, 3. April 2008 08:06

Tarve Sauli,

so You used WinGyro (here to be downloaded from my Friend Peter Jackson`s Page) and reached above Shapes and Results. I regard that quite an Achievement. Very nice! You Finns know, how to get along!

Fasan Follow the Link. You shall be surprised!
See also Birkhuhn!

I understand You very well. I once shot a Pheasant (Fasan Follow the Link. You shall be surprised!) with a Hornady-V-Max not in the Head, but in the Body and that poor Bird exploded as well. I could use only the Tail feathers, that I still have to remind me of that Nonsense, I did! You cannot use fast fragmenting Bullets on small Game and expect any thing else, than an Explosion.

Now, when Your badly desired Prey is 500 - 1'000 m far away in the open Landscape, and the vital Range to kill it measures only 5 cm Ø You need to be a real good Shooter and need extraordinary Gear. As You have comfortably Possibility to train out to 1'200 m the most important Part, the Shooters Ability, seems on a good Path to achieve the Task. You 7 mm WSM Cartridge is a quite good Candidate to launch the tight Bullet, that You found in the LM-84. The Design goals were little Wind drift on long Ranges, given precise less Wind. The bigger Brothers have achieved Feat, but with 5 cm Ø in 500 m in Filed conditions You push the Performance of a Hunting rifle to the Limit.

I assure You with the LM-84 to have found the Optimum, I can think of, and I haven't seen better Bullets yet. They may be possible, but the Improvements will quite likely only be small. Read more on the LM-Class page.

Are You and Your Friends the only exotic Finns to hunt the Black Grouse on such Distances, or is that a common Sport? In Germany they are quite rare, except for the Alpen Mountains.

How would You like to proceed Sauli?

Regards Lutz

Error

Hello Lutz,

Thank you for the nice answer in February. I'm rather late to keep in touch, but even though busy in other areas, some thinking goes on in the background. Of course, I read with great interest the LM-71 and LM-84 information you pointed me towards.

I did however find that on the LM-84 page the table of stability calculation seems to have the data for LM-71(!) I hope you can insert the right data here, I'm looking forward to read it :-)

LM: Actually that was the Case. Thank You for You Report. I changed those Data to the appropriate LM-84 Stability data.

Also, I wonder about some 9,3 mm KJG calculations. The 9,3 WSM page and 9,3x64 page seem to be based on the exact same bullet (length/weight/splitter/BC given). Still, in WSM the bullet has a faster initial velocity (1069 m/s vs 1056 m/s) but slows down faster (300m velocity 770 m/s vs 785 for the 9,3x64). What exactly goes on here?

It is in the "Flugbahn" table of each page.

Sorry about the nitpicking. Don't mean to bother you, but I am interested in the details.

LM: I look into it. The Bullets are clean, as is the Air in that they fly. No Quirks there! My Web editing on the other Hand may contain Errors, as we just noticed. 

Best regards, Tom K., Mittwoch, 18. Juni 2008 11:38

Twist gain

Hello again Lutz,

I may have found a gentleman to rifle a barrel (or two) for your LM series bullets. My question has to do with the twist rate you recommend as initial twist starting at the throat for both the 7 mm LM-84 and 5,6 mm LM-71 bullets. I have the final twists LM-84 = 165 mm and LM-71 = 135 mm. Also with the gain twist do you use a straight linear twist increase down the barrel or a parabolic/ramped increase to give a longer run of slower twist from the throat. Any information will help as to save any waisted machining cost.

LM: Troy, to start with the half Angle after the Chamber and linearily gain to full Angle a little before the Muzzle is good Practice.

Also what was the price again for a lot of 100 or 500 of your LM-71 and LM-84 bullets.

LM: I'll write You.

And, can you ship to USA.

LM: yes.

Thanks TROY, Dienstag, 29. Juli 2008 04:34

Initial Twist on Gain twist barrels

Mr. Moeller

I have been reading your various web site threads and watching your work on the .375" and .408" Chey Tac bullets with great interest (I have spoken several times to Louis Corkern about these projects). As a consequence, I’m extremely interested in putting together a rife to shoot your 7 mm (LM-84) and .338 mm (LM-105) bullets. In that regard, I would like some specific information on what throat angles I need to use to develop a proper chamber and throat for using these two bullets. If you have any previously proposed reamer drawings that you are willing to share, that would be a great help. I would propose to use the LM-84 in a necked down .338 Norma Magnum, and the LM-105s in a .338" LM Improved, so the velocity should not prove to be a problem. The only issues that I see are getting the proper throat angle and twist for the barrel, and obtaining the bullets here in the US.

In addition to Lothar Walther, there is now an American barrel manufacturer – Bartlein – that will cut a gain twist barrel of any twist that I might desire. This would solve the gain twist aspects of the barrel issues that you were talking about with respect to the .375" LM-119. If my final twist is 7.0” for the LM-84 and for the LM-105, what would you suggest for the initial twist on the barrels? I’m just guessing, but would an 8.0” advancing to a 7.0” twist will work to stabilize these bullets? What length barrel would you suggest for these bullets and cartridges?

How long would it take to get delivery of 300 or so of the LM-84s and 300 of the LM-105s? What would the price of such bullets be? Is there anyone here in the states or Canada presently set up to take delivery of the bullets?

Jeffrey D. VanNiel, Donnerstag, 7. August 2008 15:42

Hallo Jeffrey,

thanks for Your Mail. As I recently wrote in Twist gain "to start with the half Angle after the Chamber and linearily gain to full Angle a little before the Muzzle is good Practice. "

Shipping to Canada is simple. Custom Bullets usually take 6 - 8 Weeks here + 4 Weeks over the Ocean.

Lutz

LM-84 Weitschußgeschoß

Danke Lutz!

Ich habe das Geschoß anfangs im QuickLoad nicht gefunden, mit einem neuen download deiner moeller.bul war es auf einmal drinnen :-). Demnächst wird meine Remington Seven fertig werden, neuer Shilen 56 cm Lauf mit 228,6 mm Drall-Länge, und neues Schmidt & Bender PM II 3-12x50 mit Mil-Dot 2. Generation. In Amerika schießen die Jungs mit den 7 mm-Short-Kalibern (7 mm RSAUM und 7 mm WSM) auf den langen und sehr langen Distanzen zum verblüffen genau, zwar mit Bleierner Sippe.

LM: Auf Pappe können Sie damit keinen großen Schaden anrichten oder jemanden vergiften.

Laut Amerikanern sind die 7 mm Geschosse - der Bleiernen Sippe - jene mit dem höchsten BC-Wert bei idealem Gewicht (BERGER VLD, CAUTER, JLK VLD oder SIERRA MATCHKING - 11,34 Gramm bis 12,25 Gramm), also ideal zum Langstreckenschießen, .30-Geschosse brauchen um so einen BC-Wert zu erreichen zu viel Geschoßmasse, sind also zu langsam, oder brauchen viiieeel mehr Pulver und sehr lange Läufe um schnell genug zu werden, und auch die 6,5 mm BC-Werte kommen an die 7 mm BC-Werte nicht ran.

http://www.6mmbr.com/7mm284.php

Anbei 2 QuickLoad-Ladungen mit dem LM-84, aus dem kurzen dicken (=weniger schwingenden) 560 mm Lauf bis zu 895 m/s schnell bei 100% umgesetzter Ladung. Denkst du das LM-84 wird mit 228,6 mm Drall ausreichend stabilisiert, da du in deiner Netzseite 165 mm Drall empfiehlst?

LM: Fabian, bitte. Du kannst doch lesen. 229 mm sind 39% länger als 165 mm. Völlig ausgeschlossen. Bei 3,95 längerem Drall würde ich mal rechnen abe rso ist das völliger Unsinn.

Mich würde nämlich interessieren, auf 1000 Meter (NUR AUF PAPIER!) genau zu treffen, und das nicht bloß mit einzelnen Zufallstreffern.

LM: Schafts du sicher.

Da es Norma 7 mm RSAUM Hülsen nicht gibt, werde ich nun Norma .300 RSAUM Hülsen bestellen, und dessen Hals auf 7 mm reduzieren, da Norma nun mal bessere Hülsen baut als Remington.

LM: Kein Frage. Tatsächlich solltest Du dafür aber bei 7 mm WSM und 165 mm Drall bleiben. Dafür und für große Weiten ist das LM-84 nämlich bestimmt - aus langen Läufen.

MfG Fabian, Donnerstag, 3. Juni 2010 13:19

229 mm Drall ist viel zu lang für LM-84

Hallo Lutz!

Der Kurzdrall von 165 mm ist für das 47 mm lange LM-84 sicherlich ideal, aber mein 228.6 mm Drall ist demnach also (leider ?) zu lang. Da ich, um die 1.000 Meter zu versuchen, nicht tausende Euro ausgeben will, werde ich deshalb leider auf das LM-84 verzichten. Auf der Jagd wird die nächsten Jahre (so wie es auch die letzten Jahre war) das 31 mm lange 7 mm KJG mein fixer Begleiter!

Mal probieren wie das Lutz Möller KJG auf sehr lange Weiten treffen wird - vielleicht gar nicht so schlecht, denn wenn es in der Nähe trifft, kann es das bei guten Bedingungen auf langen Strecken (auf Papier) sicherlich auch, auch wenn die Winddrift und Flugbahn des LM-84 mit BC-Wert 0.973 alles anderen in den Schatten stellt.

Vielleicht probier ich auch mal die Bleierne Sippe, denn beim 11,66 Gramm BERGER VLD (Very Long Draw), BC-Wert 0.659, wird ein 228.6 mm Drall (9“ twist) empfohlen. Ich werde berichten.

Gruß, Fabian, Freitag, 4. Juni 2010 13:11

Energy calculator

Currently (early 2008) Bisley limits fired kinetic Energy to 4'500 Joule. So watch out for local Range limits an Rules to obey.

Velocity m/s Masse g
Joule

New Rifle for 7 mm LM Class bullets

Dear Mr Moeller,

I am going to build a new rifle for long range shooting in 7 mm SAUM.

LM: No. Read Warning.

I’d like to use a progressive twist barrel to use your LM84 bullet. I have found a lot of informations in your “LM class Bullets for windy long ranges”( which is actually unavailable, sub revision?) , summarizing: cal. 7mm saum, barrel Bartlein/Lilja (the gunsmith is Kelbly) barrel lenght 32”, 4 drive bands, gain twist from 8,5” to 6,5” to the muzzle, a separate 2° Angle Throat reamer for a 2 degree full angle cone.

I didn’t neverthless understand what is the correct Twist angle, I hope you can tell me this one, so I can give to the gunsmith all the data he needs to make the rifle.

LM: Read Barrel, Twist and Throat.

Now I need to know how much time you need to make a parcel of 200 and 500 bullets and the price for both.

LM: Custom Ordes no less than 1.000.

I have too a .300 wm rifle and I mean to use its action (a Bat Machine) to change the barrel for a new 8mm, with the idea to test a 8mm cartridge for F-Class open matches using a heavvy and fast bullet. I’d like to use the 8x68s cartridge and your LM 102 bulle (the maximum diameter allowed). I have read about a wildcat cartridge named “8 x 68 Taras” which you have made but I didn’t find informations about it. Can you tell me something about this cartridge? Is it similar or interchangeable with the 8 x 68S? What suggestions can you give me for this caliber?

LM: That was a Custom Bullet, long Time ago.

I hope you can answer me and I can read in a shorthly time your web site with new informations. Thank you for your attention.

LM:Where will You be able to shoot that Rifle on open Ground in Italy out to 1.000 m? If You can't, this Project will be bound to fail.

Aldo Franceschin,Treviso, Italy, Sonntag, 1. September 2013 16:18