I have about 200 rounds of Federal GMM 7.62x51 175gr ammo. Does anybody know if this is the same as military M118LR ammo? Most of my dope is around this round and I am wondering if M118LR will dope the same.
|
||||||||||||||||||||||||||||||||||||||
Member
I have about 200 rounds of Federal GMM 7.62x51 175gr ammo. Does anybody know if this is the same as military M118LR ammo? Most of my dope is around this round and I am wondering if M118LR will dope the same.
Senior Member
They use the same bullet and the velocity is almost identical (2600 FGMM and 2580 M118) but I think the FGMM is a bit more accurate. Probably because the M118 is mass produced by Lake City where Federal can be a bit more selective in production. Average M118 for me was between .8-1.25 MOA and the FGMM was always below 0.75MOA.
They're pretty much the same round, but the accuracy goes to FGMM. don't count out Black Hills either. That's good stuff.
Last edited by Eurodriver; 03-31-14 at 07:18.
Why do the loudest do the least?
Senior Member
They are not the same. Mk118LR currently uses RE15 as propellant. FGMM uses IMR 4064 with a 210M primer.
Mk316 would be the mil designation for what 175 Fed GMM is.
The result, when it was standardized as the MK316 Mod 0 cartridge, was a Federal modified case (Drawing number 8347636), Federal match primer, Sierra 175 grain Matchking and 41.75 grains of IMR 4064 powder. According to the published sources this load will produce a muzzle velocity of 2640 fps out of a 24 inch barrel. The load as produced by Federal is claimed to produce under 1 MOA out to 1000 yards from an appropriate rifle. With the IMR powder the shift in velocity is only 20 fps from 0 to 100 Deg C, with the Standard deviation in velocity over 40 rounds being 15 fps or less. In contrast the M118LR loaded with RE-15 powder will see a 50 fps rise in velocity for a 50 deg rise in temperature.
The MK316 ammunition is essentially the finest possible mass produced match ammunition, comparable to the hand loads utilized by the various service MTUs. The cost is higher than M118LR, with a government cost of 78 cents per round for the MK 316 Mod 0 rather than 55 cents for the M118LR (2009 prices).
http://riflemansjournal.blogspot.com...-match_04.html
Last edited by markm; 03-31-14 at 12:38.
"What would a $2,000 Geissele Super Duty do that a $500 PSA door buster on Black Friday couldn't do?" - Stopsign32v
Senior Member
I found the 7.62 FGMM 175gr to be a rather Hot load... 2750fps from a 24" Bartlein 5R.
Senior Member
I've not shot any of it, but that makes more sense that the powder charge listed above. I mean... I'm almost at that 2640 with my load out of a 20 inch barrel.Originally Posted by HD1911
"What would a $2,000 Geissele Super Duty do that a $500 PSA door buster on Black Friday couldn't do?" - Stopsign32v
Member
Nice seeing some load data to replicate that round. Didn't realize it was published anywhere.
Member
Personally speaking the 175 GM308M2's are tack drivers, especially when your pushing the round out to distance.
Member
Agreed. My precision rifle likes the 7.62x51 GMM much better than the .308 175gr GMM. Both very accurate rounds but I can tell a noticeable difference. I have a harder time finding the 7.62 though so I'm happy to shoot them both.
Member
I actually was wondering if there was a difference between the 308 & 7.62. It sounds like there is in your experience. I originally started buying the 7.62 because I thought I would get more reloads out of the cases (From what I gather the main difference between 7.62 and 308 are the 7.62 cases are generally a little thicker to make them more reliable in machine guns).
By the way, in hindsight this was not a great idea. I do not have enough experience to confirm this, but I read the Federal cases are made of softer metal than most other manufactures. The result is the case flows more and gets thin at the top faster. I have noticed more brass buildup on my bolt with Federal though.
Member
Yes, they are different rounds due to propellant differences. Also Lake City production seems to have slightly less accuracy. As far as dope on the gun you should be GTG with either. Depending on the lots, your shooting, gun, etc. the differences can be quite small.
If you've zeroed on either it will be very small adjustments when switching loads.
SF
Posting Permissions
Reply With Quote
Bookmarks