Range Report Faster than normal FGMM 175gr?

[You-Two]

I have a couple boxes of FGMM 175gr (GM308M2) that averages 2715 fps out of my 24" Savage 10 5R 11.25" twist rifle. Measured with a magnetospeed chrony on two separate occasions. I was a bit surprised at this since the box states 2600 fps and most reports I've read are around that. I also bought a case of 200 rds (probably from PSA) which is in a newer style box, but same product code. This ammo measures 2625 fps out of the same rifle. I'm going to build a practice load to match the FGMM with some Nosler 175CC bullets I've had a while, so I was curious about the velocity difference.

I broke down one round from each lot. Bullets and cases were the same...175gr SMKs. Both powders looked like the same type, closest looking to IMR 4895 to me. Shorter length than my IMR 4064. I know it's not typically canister grade powder, so more for general info.

Old lot powder: 41.2gr
New lot powder: 40.4gr

Without knowing that both powders are the same, I'm going to speculate that the higher charge is the main cause of the higher velocity, since it's pretty much the only difference. Anyone have a similar experience with a faster than normal velocity for FGMM 175gr factory ammo? It was just kind of surprising to me. Maybe 25 fps difference, but 90-100 fps is a bit much for match ammo. My rifle is consistent for velocities with other factory ammo (+ or - a bit)

The fast lot # is V37K208P41211. Both boxes claim 2600 fps at muzzle.

 

[tnichols]

That lot running 2715 might be a shade on the warm side ?. Your other lot at 2625 I would say is more typical considering your barrel length.

My 20” lives on a steady diet of FGMM in 175, and lot to lot is fairly consistent. 2505 to 2535 seems to be the norm.

 

[MOUNTIC]

I've has some fast results with FGMM 175s out of 16 inch guns right at 2600 with a suppressor. The same ammo was 2625 out if a 20 inch gun. Some just sling em faster then others.

 

[m1marty]

The latest lot of 762M2 I got has been pretty hot. Slight bit of primer flow and shooting a bit higher than my old dope. Haven't ran any across a chrono but it's noticeable compared to some of my other loads

 

[m1marty]

Same rifle (m24 with huge factory chamber), same day.

 

[You-Two]

That lot running 2715 might be a shade on the warm side ?. Your other lot at 2625 I would say is more typical considering your barrel length.

My 20” lives on a steady diet of FGMM in 175, and lot to lot is fairly consistent. 2505 to 2535 seems to be the norm.

The consistency is my reasoning to buy a few cases for a stash. I’ll just have to test each lot to know the data, but I was surprised by the difference.

I had a 175 load for my FN SPR that ran 2700 and shot well.

 

[You-Two]

I've has some fast results with FGMM 175s out of 16 inch guns right at 2600 with a suppressor. The same ammo was 2625 out if a 20 inch gun. Some just sling em faster then others.

I thought that the first time I measured, but it ended up being faster in both the Savage and a Win 70. Just a fast lot I guess.

 

[STLSteve86]

Both barrels 24” 1:11.25? I had the same out of a bartlien 24” my hand loads were 2723 as well.

 

[You-Two]

Both barrels 24” 1:11.25? I had the same out of a bartlien 24” my hand loads were 2723 as well.

No, the Win 70 is 22.5” with a factory HV 12 twist. It shoots slower than the Savage, but the fast lot was consistently faster in both rifles.

 

[MCSO1357]

I get consistent 2650 fps with 175 FGMM out of 20” barrel, measured with Magnetopeed.

 

[FromMyColdDeadHand]

I have some older (couple years) 7.62x51 175gr and in my ACC-SD inch model, I was running 2600 at 75F. I was kind of surprised that it was that fast, I expected about 2500. That was with a Labradar.