M80 Replication

[Rich 10mm]

I am trying to replicate the 7.62 NATO cartridge, designation M80, which will be fired from a Sig 716 AR-10 style rifle using a Hornady 150gr FMJ. Any recipes to get me started would be appreciated.

 

[IALoder]

What has gotten me really close to PPU M80 in my 20" LR308 for me has been around 42gr AA2230/X-Terminator, 43-44 gr TAC, and 44-45gr AA2520, all in LC or other military brass, using the Hornady 150 fmjs. All loads seem to be in "service rifle" data as well. As always, start low and work up!

 

[Nature Boy]

To replicate M80, my recipe would be:

150 FMJBT. Brand won’t matter. The cheaper the better

42g +/- 1.0g of H4895, IMR4895, AR Comp, RL15 or IMR4046

Lake City Brass

Primer of your choice

2.800 OAL

 

[Slamfire]

I recommend powders at the H4895/IMR4895/AA2495 burn rate. The 7.62 cartridge was developed with IMR 4895 as its propellant, so port pressures will be appropriate as long as you are not hot loading the cartridge. I purchased kegs of AA2520, a ball powder, and Accurate Arms told me they blended the stuff to the IMR 4895 pressure curve. AA2495 is their copy of IMR 4895 but stupidly, they call it 2495, and that confuses everyone.

Since IMR went to a short cut IMR 3031, I am very positive about that powder in gas guns. It is faster than IMR 4895, and I think that is OK if kept within velocity. A slightly fast powder should give a lower port pressure and lower chamber pressure on extraction. The less the case grips the chamber, the better the extraction. The more case drag during extraction, the greater the potential for a malfunction. Ideally, the case extracts without any friction, as friction is hard on the extractor, slows the mechanism, and causes more trouble than it is worth.

The slowest I would go is IMR 4064, but, that powder is a long stick powder and does not throw well in my Dillion 550B. So, I prefer the short stick powders.

If you have one of those stubby 18" barrels, you will be disappointed in the velocity of your ammunition, as you loose a lot of velocity. Don't try to compensate by pouring on the coal!

I try to keep my gas gun velocities with a 150 just at 2700 fps or less. Pushing the velocity envelope just increases the slamming and banging, and in hot weather, jams. Over gassing the gun leads to problems.

Loading a 150 with 42 to 43 grains of IMR 4895 gives all the velocity and function I need.


PTR91 18" barrel

148 gr IMI FMJBT 42.5 grs AA2520  wtd Lot 9595 Czech Mixed LC WLR     OAL LT 2.800, set to cannelure  

30 April 2008 T =  75 °F     

Ave Vel = 2496    
Std Dev = 33     
ES = 88     
High = 2537     
Low = 2449     
N = 10     

poor accuracy    


150 gr Hornady FMJBT 42.5 grs AA2520 wtd Lot 9595 Czech Mixed LC WLR   OAL 2.785    

30 April 2008 T =  75 °F     

Ave Vel = 2499     
Std Dev = 29     
ES = 94     
High = 2539     
Low = 2445     
N = 10     
   

best accuracy, shot high      


150 gr Hornady FMJBT 43.0 grs AA2520 wtd Lot 9595 Czech Mixed LC WLR   OAL 2.785    

30 April 2008 T =  75 °F     
 

Ave Vel = 2544  2551    
Std Dev = 32      
ES = 84      
High = 2574      
Low = 2490      
N = 5     

poor accuracy

Ruger M77 MKII 26 " Barrel 1:10 twist

148 gr IMI FMJBT 41.0 grs IMR 3031  wtd Lot 385 Mixed LC WLR      OAL LT 2.800, set to cannelure

30 April 2008 T =  62 °F              

Ave Vel = 2697      
Std Dev = 29      
ES = 105      
High = 2743      
Low = 2638      
N = 10      

 

150 gr Hornady FMJBT 40.0 grs IMR 3031  wtd Lot 385 Mixed LC WLR     OAL 2.785

30 April 2008 T =  62 °F      

Ave Vel = 2676      
Std Dev = 21      
ES = 61      
High = 2705      
Low = 2644      
N = 10      

150 gr Hornady FMJBT 41.0 grs IMR 3031  wtd Lot 385 Mixed LC WLR      OAL 2.785     

30 April 2008 T =  65 °F      

Ave Vel = 2718      
Std Dev = 54      
ES = 157      
High = 2780      
Low = 2623      
N = 10      

Outstanding accuracy      

150 gr Hornady FMJBT 42.5 grs AA2520 wtd Lot 9595 Czech Mixed LC WLR 
   OAL 2.785     

30 April 2008 T =  65 °F      

Ave Vel = 2700      
Std Dev = 29      
ES = 89      
High = 2734      
Low = 2645      
N = 10

 

[Charlie98]

I'm working off a 16" barreled M1a, so my velocities are different, but the load would be the same...

M80 runs about 2600fps out of my rifle, adjusted up or down for certain flavors of M80, and shooting temperature. That is... RG, FNB, LC (18), and also Prvi white box (not NATO,) and CBC (can't remember if it's NATO, but I don't think so.)

My M80 equivalent load is 'nearly equivalent' with an average velocity of 2500fps. I don't see a reason to push for the extra 100fps if all I'm doing is killing paper or steel, but the zero is the same to 200yds. These loads are with any generic 145-150grn FMJ bullet, including the 145grn Prvi, 147grn Winchester, and... now... the 150grn Hornady bullet. Note that I do not seat the Hornady bullet to the cannelure, because it would deep seat the bullet... I seat at 2.770-2.780" with a slight taper crimp to bump the case mouth in.

43.5grn IMR4895
42.0grn IMR3031
42grn H335
43.5grn TAC

Loaded in LC or Prvi brass, using a CCI #34 primer except with TAC, which gets a standard primer.



Slam mentioned IMR3031 in the .308/7.62mm, I've basically abandoned IMR4895 for IMR3031 in my 16" barreled M1a... it really works well there... not that IMR4895 was any slouch. The H335 loads produced huge muzzle blast, and a 4" flame shooting out of my brake, so it's is a 'just in case' load. Wild card is TAC, which I've just finished working with; it gave me some very good numbers and accuracy, even with some poor quality bullets (RMR seconds,) so I'll be working with TAC, again, and the Hornady 150's.

 

[Rich 10mm]

Thanks guys I appreciate all the info. I’m using a 16” suppressed barrel

 

[Slamfire]

Thanks guys I appreciate all the info. I’m using a 16” suppressed barrel

Don't own a suppressor, but guys who have suppressors have all sorts of issues because the pressure inside the barrel drops slowly. You may end up cutting loads by two to three grains to avoid function issues. Tell us how it goes. I would say, stick to the fast powders, don't go slow.

 

[jmorris]

Since IMR went to a short cut IMR 3031,

Do you happen to know when that was?

 

[GeoDudeFlorida]

Loading a 150 with 42 to 43 grains of IMR 4895 gives all the velocity and function I need.

That recipe goes back to the early 1960's Lyman's loading data for the .308/7.62 NATO and is very close to the .300 Savage 150gr. jacketed accuracy load (the load the NATO cartridge is based on). For IMR 4895, 41gr. is start, 42/43 is optimal, 45gr is max and rarely accurate. 42/43gr. of IMR 3031 is a little faster but I've never seen any advantage to 3031 over 4895 in that cartridge. NB: I sold my last .308Win years ago and my last 7.62 NATO rifle a few years before that so it's been a while since I used or loaded for either one. Just in the interests of full disclosure, I always used Lyman's data and stuck as close to the .300Sav/.308Win data as possible in all of my rifles for either chambering. The 7.62CETME in FR7/FR8 rifles I ran with much, much lower charges.

 

[Slamfire]

Do you happen to know when that was?

I don't know a transition date. I purchased a pounder before COVID and it was short cut. Before that, all the IMR 3031 I used dates back to the 60's and 70's.

I try to tell the powder guys, keep me on speed dial. They don't listen....................

 

[Charlie98]

Now... if we can get them to come up with an 'IMR4064SC...' I'd be in heaven.

 

[Rich 10mm]

Prepping brass now. So I fired some factory M80 and had a lot of gas blowback from suppressor. I saw a charging handle called the Gas Buster that supposedly redirects gas away from the shooters face. Has anyone tried one? I’m assuming it’s BS, don’t see how a handle can do that. I use the suppressor on other rifles and calibers but never had this amount of gas in my face.

 

[IALoder]

If it was the "M84 gas buster" charging handle then yes, it does a decent job of getting the gas out of your face. Best way to help with the gas is an adjustable gas block, which I've found to almost be a requirement on a LR308/AR10 anyways.

 

[FLIGHT762]

Now... if we can get them to come up with an 'IMR4064SC...' I'd be in heaven.

Accurate XMR4064 is now made at the same General Dynamics powder factory in Valleyfield, Canada as IMR 4064 is. Accurate XMR4064 is short grained.

The older XMR4064 I have was made in the Czech Republic, but it is now sourced from the Valleyfield plant in Canada. I would try a can of the XMR4064 if you come across it.