dpete

Looking at the speed increases per .3 gr increase in powder charge: 44.9gr = 2355 fps -9 fps WTF? 45.2gr = 2346 fps +43 fps 45.5gr = 2389 fps +15 fps 45.8gr = 2404 fps +14 fps 46.1gr = 2418 fps +17 fps 46.4gr = 2435 fps Given the seemily consistant mid teen fps speed increases toward the top of the ladder. Is it worth pushing the pressure envelope with an additional .6gr of powder to get what might be 30 more fps out of a 47.0gr load?

@Radioactive If you haven't already, read this thread about 375 Socom and what he says about subsonic use. http://458socomforums.com/index.php?topic=2791.0 Whether or not his statements are factual or not I have no idea.

Here is where the 47 gr load idea came from. https://www.shootersforum.com/wildcat-cartridges/99551-ar-15-375-socom.html As I said I don't see how 47 gr even fits in the case with a bullet on top of it not compressing the schit out of the powder. Scroll down to post #10 in that thread. He got 100fps less speed with .6 gr more powder and with 2.170" COAL. My COAL was 2.175". If his was one of the first barrels made by Tromix then I think its safe to assume his and my barrels are both 18". The 18" barrels have since been replaced by 16" and 20"

Here is a quickload data sheet run by someone with way more experience with the 375 Socom.200 gr Sierra FP load data - 1.webp

46.4 gr may be slightly over pressure as it is but there weren't any signs of it. Watching the powder climb up inside the case neck as the charges went up made me wonder how it is claimed 47 gr is even possible and not have the bullet seriously compressing the powder.

Nothing that screamed at me STOP!

@Radioactive The one word to describe this rifle is Impressive. For an AR15 the recoil is fairly impressive but not ungodly. About as hard as my 308AR was but much quicker. The bark this thing has when a round is touched off is also impressive. The first comment from the guy next to me at the range today was, "wow is that thing loud". This was by far the easiest load development I have ever had for a rifle of any caliber, impressive! Ok, cutting to the chase, putting pictures where the claims are. Upper right and lower left fliers All targets are 5 shot groups at 50 yards. Sierra 200 grain Flat Points over AR-Comp. Considering these bullets have the ballistic coefficient of a smooth rock they sure shoot great and I can see why those with experience with the 375 say its the bullet of choice.

Same with mine. 2" of can under the handguard but the handguard is carbon fiber. SBA3 on the back end.

Yup. They's a little big.

Test loads are loaded up. 44.9 gr up to 46.4 gr of AR-Comp in .3 gr increments. These are gonna be deer thumpers. For comparison. Left to right. 5.56 6.5 Grendel 300 BLK 375 Socom

@Radioactive THESE THINGS ARE CARNIVOROUS! They try to eat their little bretheren. To make up a decent size batch of brass to run in the wet tumbler I tossed everything I had that was dirty into one run. The 375, some Grendel, 5.56, and some 300 BLK all together. The Grendel brass was safe, it was too big to swallow, but the 5.56 and the BLK were in serious danger. It turns out that a fired 375 case when put into the same cleaning batch as 5.56 and 300 BLK will try to eat the smaller cases. The result reminds me of a small Northern Pike or Muskie that tried to eat a Perch that was a bit too large. This is what a semi-eaten 5.56 case looks like. A BLK case fits completely inside, its base flush with the 375 case mouth. I had to poke the BLK cases out with a large straightened paper clip in order to get a pliers to grab and pull the things out. Do not mix 375 and 5.56 based cases in a cleaning batch! On a positive note I hope to be shooting test loads of the 375 on Saturday.

I like the SBA3 that I have.

Socom brass is in the wet tumbler getting nice and cleaned up. Next is rinse, dry, and run all of them through the sizing die. Then test loads commence.

No subs for me in 375 Socom. I've already got a sub gun in 300BLK and running subs quietly in the 375 would mean another suppressor which I'm not interested in getting. If nothing else give Tony a call at Tromix and see what he says. There is also an entire section dealing with the 375 on the 458 Socom forum that has load data threads in it.

I may have some time to get some test loads put together this week.

The same with this guy(Bob). Greets me at the door when I come home and begs for scraps from the table.

Here is my version attempting to get stoned on catmint out in the garden. Last year my son and I were working on the boat that was parked close to those plants. He walked through them a couple of times and when we came into the house the cat damm near made love to his shoes! Funnier than heII! At close to 18 he now has purrfected the art of napping.

Updated 5/25/20 Rifle Calibers @ $2.00/ lb Caliber lbs .223 0 .243 3/4 spoken for .270 3 3/4 .308 6 spoken for 30-30 3 30-06 10 Pistol Calibers @ $2.00/ lb Caliber lbs 38 Special 10 38 Special (nickel) 12+ 357 Magnum 0 45 ACP (Lg primer) 0 Rifle Calibers @ $ .25 each Caliber num. of pieces 22-250 6 260 1 spoken for 270 WSM 1 270 WSM (nickel) 1 280 5 300 Savage 3 300 Win Mag 24 spoken for 300 WSM (nickel) 9 spoken for 308 LC Headstamp 20 spoken for 325 WSM 1 30-06 LC headstamp 99 spoken for 338 Win Mag 3 35 Rem 4 350 Legend 2 444 Marlin 19 450 Bushmaster 38 50 Beowulf 1 6.5 Creedmoor 318 6.8 SPC 9 7mm-08 6 spoken for 7mm-08 (nickel) 2 spoken for 7-30 Waters 27 7mm Mag 9 7mm Mag (nickel) 19 7.62X54R 12 8mm Mauser 8 spoken for Pistol & Rifle Calibers @ $ .10 each Pistol Caliber num. of pieces 10 mm 476 spoken for 44 Mag 12 Rifle Calibers num. of pieces 7.62X39 (brass, not steel) 85 300 BLK (not processed 223) 130 spoken for 30 Carbine 12 spoken for

Got 300 of the Sierra 200 grain FP in the mail yesterday. Now I can start my own load development and see what this thing can really do.

Why not? Thats what we do best around here.

The 375 is pushing about twice the bullet at just about the same speeds as a supersonic Blackout. Granted, the bullets and brass are much harder to come by than for the Blackout but that is what reloading is for. There are even short 375 barrels for building pistols.

@Boot_Scraper Tromix also has a 358 SOCOM. I wonder what the velocity difference would be between that and your 358 Yeti given they both single stack in a 556 mag and have virtually the same OAL

Oh hell yes! At the distances we get shots at deer up here (75 yards and in) this should be boom flop on them. That is if I'm not sitting with one of my Grendels or my suppressed Blackout pistol.

Thanks! Its definitely a thumper. Not as much as a .458 though and flatter shooting. The recoil is similar to a 308 AR except from a smaller package. Maybe a little quicker but not any harder.

RANGE REPORT I got out this morning and shot up the loaded rounds that came with the rifle. I am impressed. First 4 shots were getting the scope close to zeroed. Numbered 1-4 on the targets. The 5 shot group followed immediately afterward. The 4 shot group immediately after the 5 shot. That was the end of the 200 grain Sierra FP I had. The 3 shot group was 270 grain Sierra spitzer SP. Only had 3 of those. 200 grain Sierra FP 270 Grain Sierra spitzer All shots taken at 50 yards. Velocities on the 200 FP ran in the upper 2100 fps and for the 270 SP in the upper 1900 fps. I have no idea what powder was used on any of them but I'll be doing my own load work up once I have bullets in hand to load.