Summary: an available mil-surp stick powder good for medium/heavier .308 loadings. Possible 6.5CM use, but may have issues filling the case enough to get desired velocity. Temp sensitive.
(Not even going to attempt an in-depth review at Molon’s level of detail.)
FSP-759 is a Russian Mil-surplus powder available via Gun Broker auctions, as it is being sold by “ST Auctions” which is Federal Armament (FedArms.com, not currently in stock on their website, as they seem to get better profits at auction.) They list it on a burn rate chart as just slightly slower than 2000-MR, H-380, IMR-4320, N-140, and about the same as Big Game.
Powder is a stick powder, with a grain is slightly longer than Varget, but slightly smaller diameter. I did not expect it to throw well, so charges were metered on a Chargemaster. A drop tube may be needed to get above 45.5 or it will be a slightly compressed load.
Rounds were loaded with ex-CMP M72/173gn bullets, 1x fired then neck sized FC brass, and S&B large rifle primers. OAL was slightly longer than SAMMI (but in my notes at home, update later). Barrel was 24 inch 1:10 twist .308 Sako TRG. I would think a 175 SMK would give similar results.
Initial testing was just 2 rounds of each for ballpark chrono velocity using a Magnetospeed and to look for pressure signs. Barrel was not cooled between shots, so the last few were on a warm barrel, outside temp was 64F:
45.0: 2730, 2741fps
45.5: 2752, 2759fps
46.0: 2802, 2789fps
46.3: 2817, 2808fps
No pressure signs noted.
A few weeks later, I decided to try and chrono 5 round groups for temp shift. Cold rounds were packed onto a cooler with a reusable ice pack, and read 40F on my non-scientific thermometer. Ambient/warm rounds were at 80F, and hot rounds were left on a car dashboard in the sun to a temp of around 130F (perhaps hotter). All rounds were 45.2gns of FSP-759 with the same 173 bullet and S&B primer, etc.
cold rounds: average 2694fps cold bore
warm rounds: average 2726fps warm bore
hot rounds: average 2782fps hot bore from shooting the prior ten rounds
So 32fps average increase for approx 40F temp increase between cold to warm and 56fps increase for 50+ temp increase from warm to hot. So approx 1fps per degree F, using a too small of a sample size and not very scientific temp measurements.
Also loaded a few rounds with 190 SMK to get initial data (80F), cool barrel:
45.2: 2686, 2701fps
45.5: 2719, 2723fps. Light ejector swipes on the brass.
Seems worth looking for 175gn or heavier bullets at if powder availability remains an issue. Accuracy was comparable to my standard .308 load of 41.7 gns of AR-Comp (at 2730fps) with the 173 gn bullet.
(Not even going to attempt an in-depth review at Molon’s level of detail.)
FSP-759 is a Russian Mil-surplus powder available via Gun Broker auctions, as it is being sold by “ST Auctions” which is Federal Armament (FedArms.com, not currently in stock on their website, as they seem to get better profits at auction.) They list it on a burn rate chart as just slightly slower than 2000-MR, H-380, IMR-4320, N-140, and about the same as Big Game.
Powder is a stick powder, with a grain is slightly longer than Varget, but slightly smaller diameter. I did not expect it to throw well, so charges were metered on a Chargemaster. A drop tube may be needed to get above 45.5 or it will be a slightly compressed load.
Rounds were loaded with ex-CMP M72/173gn bullets, 1x fired then neck sized FC brass, and S&B large rifle primers. OAL was slightly longer than SAMMI (but in my notes at home, update later). Barrel was 24 inch 1:10 twist .308 Sako TRG. I would think a 175 SMK would give similar results.
Initial testing was just 2 rounds of each for ballpark chrono velocity using a Magnetospeed and to look for pressure signs. Barrel was not cooled between shots, so the last few were on a warm barrel, outside temp was 64F:
45.0: 2730, 2741fps
45.5: 2752, 2759fps
46.0: 2802, 2789fps
46.3: 2817, 2808fps
No pressure signs noted.
A few weeks later, I decided to try and chrono 5 round groups for temp shift. Cold rounds were packed onto a cooler with a reusable ice pack, and read 40F on my non-scientific thermometer. Ambient/warm rounds were at 80F, and hot rounds were left on a car dashboard in the sun to a temp of around 130F (perhaps hotter). All rounds were 45.2gns of FSP-759 with the same 173 bullet and S&B primer, etc.
cold rounds: average 2694fps cold bore
warm rounds: average 2726fps warm bore
hot rounds: average 2782fps hot bore from shooting the prior ten rounds
So 32fps average increase for approx 40F temp increase between cold to warm and 56fps increase for 50+ temp increase from warm to hot. So approx 1fps per degree F, using a too small of a sample size and not very scientific temp measurements.
Also loaded a few rounds with 190 SMK to get initial data (80F), cool barrel:
45.2: 2686, 2701fps
45.5: 2719, 2723fps. Light ejector swipes on the brass.
Seems worth looking for 175gn or heavier bullets at if powder availability remains an issue. Accuracy was comparable to my standard .308 load of 41.7 gns of AR-Comp (at 2730fps) with the 173 gn bullet.
