This data is totally UNSAFE for anybody to use.

Do NOT use this data under any circumstance.

It is totally safe in my gun, but NOT IN YOURS.

REPEAT, DO NOT USE THIS DATA.... so endeth my CYA. Thank You for your attention.

VERY EARLY TESTING... Cheap GM barrel on a Remington 700 action (100 yards (smallest dots are 3/4" for scale)).

Temporary 1.2-6 Minox ZA power scope.

Final numbers for 200gr (AA2520 and AR Comp) and 270gr with AA2520

The 200gr likes the 2520, 49.5gr getting 2575fps avg.... Right most group at 100yds.



270gr with AA2520 was not as good as the AR Comp (top group was 39gr at 1920fps). I believe this is a case volume issue due to the larger bullets.



Bottom line:

1. AR Comp for heavier bullets >235gr, AA2520 for lighter bullets.

2. Still some headroom (not much in the light bullets with 2520 (still not 100% case capacity)

2. Fire-forming makes no difference in performance.

BTW the 200gr at 2575fps with AA2520 .5 MOA on a temp 6X scope, at higher power may tighten up (oh yeah).

This data is totally UNSAFE for anybody to use.

Do NOT use this data under any circumstance.

It is totally safe in my gun, but NOT IN YOURS.

REPEAT, DO NOT USE THIS DATA.... so endeth my CYA. Thank You for your attention.

Finally got some range time with the Carbine and the SBR. Bolt gun is already G2G.

Gas port on the SBR needs to be opened up a bit (maybe 30%-40%).

Adams Arms piston kit on the Carbine sheared rod on the first short, but still cycled the next round.

Ammo is safe in all three of my guns (knew it was safe in the R700 bolt already). It is NOT SAFE in your guns.

Lane .458 can as well as custom built .375 Lane mitigate recoil to about the same as .223 (i.e. "nothing") while pushing .375" pills between 2,200 and 2,600 FPS.

.375 Socom is the perfect AR-15 caliber IMHO. There is nothing on this Continent that it would not cleanly kill.

Assume the AA piston rod is a factory defect. I will get another and go again. No targets today. Function testing only.

Bump... changed pics form **I miss Obama** **I miss Obama**, **I miss Obama** crappy Photobucket to Phototrail to get them to work.

Same batch of barrels we built... as the one Tug is now selling. Tugs should be much more accurate (his is a much heavier barrel).

For folks in the .375 SOCOM game with me... consolidated data.

With the Sierra 200s back in Stock FINALLY... time to work on some loads further. Asked a friend to run me some QL data based on what we had GUESSED would be good powders... His typing is in blue.

Preamble:

Do NOT use this data under any circumstance. It is totally safe in my gun, but NOT IN YOURS. If you choose to use... you are using at your own risk and ALWAYS start with reduced loads)... so endeth my CYA. Thank You for your attention.

Three guns used:

Remington 700 (22" GM barrel 1:12)
18" AR-15 (AA piston)
10" SBR

Test scopes were 1.2-6 Minox ZA-5 HD (those scopes have since been changed to 2-10 Minox ZA-5 HD... the SBR kept her 1.2-6x). Can is a custom Lane .375 Cory made for me.



--------------------------------------

Tested Pills: 200 Sierra (2900s)



0.840" Long

2.126" Loaded COAL (box says 2.130")



Target @ 100 yards (right most group) Max load of A2520 which was 49.7gr 100% fill. Vel: 2385 (ACTUAL was 2575 Average)



Dots are 5/8" or 3/4" (I forget)... see barrel muzzle at bottom of pic for further scale.

Looks like A2520 was a pretty good guess. A couple alternates you may want to try with their max loads (based on 35000psi) are:

A2495 max 47.9gr which is 103% fill vel: 2441
A4064 50.6gr which is 110% fill vel: 2424
AR Comp 45.1gr which is 99% fill vel: 2411
IMR 3031 48.8gr which is 104% fill vel:2405

The above powders listed a higher predicted velocity than a max load of A2520 which was 49.7gr 100% fill. Vel: 2385

Based on the barrel time of the accurate 200gr loads with 49.5gr of A2520, 2.126" oal, 2373 fps, the following loads will produce a similar barrel time (1.254 millisconds):

A2495 48.0gr, however this is a max load at 35477psi.

A4064 50.7, however this is a max load at 35289psi

AR Comp 44.5 gr @ 33614psi

IMR 3031 45.3gr @ 33861 psi


He and I are working on a "Barrel Time Theory" to predict load accuracy across a variety of powders.

---------------------------------------

As for the 270... why bother?

I bought these pills (LOTS OF THEM) as Factory Seconds from Midway at $0.18 each... I am really trying to get them to work as cheap plinkers for the AR and SBR...



FYI... I also own a .375 RUM, but whoever wants to shoot a .375 RUM several hundred/thousand times please raise their hand.

SO...

270s are:



1.127" Long

2.213" Loaded COAL (box says 2.215")

[img]http://pic20.picturetrail.com/VOL1325/13762207/24785736/413594132.jpg[/img]

Target @ 100 yards (top most group) THIS LOAD IS BEYOND MAX!!!

39gr of AR Comp at 2.213" says 2074fps(ACTUAL was 1920 AVERAGE), and 37151psi. The barrel time is 1.401 ms. This is definitely a max load based on the program.

The best estimated powders based on 35000psi max pressure are:

A2495 40.2gr 98%fill 2051fps
A4054 42.6gr 104%fill 2046fps
IMR 3031 38.8gr 99%fill 2039fps
AR Comp 38.2gr 94% fill 2035fps

Based on barrel time of 1.401ms,

IMR 3031 39.6gr, 101% fill, 2082fps, 37236psi

I'll report back as we continue our tests

P.S. My water measurements were:

Fired brass with spent primer

183.2 grain empty

242.4 grain full

End of this video is good recap on the Sierra 2900s

https://www.youtube.com/watch?v=lCtvdRHVeaE

Not quite the math of a 35 Whelen, but very much the math of a .375 Whelen.

https://en.wikipedia.org/wiki/.375_SOCOM

https://en.wikipedia.org/wiki/.35_Whelen

https://en.wikipedia.org/wiki/.375_Whelen

Probably the most formidable AR-15 round ever devised out to 250-300 yards.

Neck and neck with the .358 Winchester

https://en.wikipedia.org/wiki/.358_Winchester

JUST an FYI... MidwayUSA has sold out of the Sierra 2900s again (No Backorder).

I got mine from Natchez (had some discount codes (happy to share)).

https://ammoseek.com/reloading/bullets/.375-diameter/200grains.

Just saying if you are going to try these for yourself, better get the pills before they disappear again... they are only made annually or biennially (to the best of my knowledge).

Or you can swage your own and not have to worry it. Just saying 🍻

Now this is something I need to get into next, especially for .510 pills.

Four rounds in the center are 100 yards 200 gr Sierras from Tug's old upper... loads and shots by RW.

Assume data of A2520 which was 49.5gr +/-



*Disregard stray shots (zeroing)

Data is correct but the upper in question is my original upper that was traded to tug and found its way home!

Oh this target was shot outdoors in light wind 5mph or less!

First deer with the 375 socom!
https://vault.myvzw.com/webcs/app/share/invite/ZHgFtBXsxT

Unlike the BS that Wilson pulled to build .458 SOCOMs (unlicensed TJ reamer)... Wilson Combat now has an agreement with Tromix to build .375 SOCOMs...

So now everybody will be jumping on the bandwagon.

I wonder if WC will do some underhanded renegotiating again like they did before. WC sucks **I miss Obama**

Newest member of the 700 Club...

Heavy barrel .375 Socom

Figured out something the other day...

---------------------------------

.375 and .458 SOCOM are 35k pressure rounds

https://en.wikipedia.org/wiki/.458_SOCOM

...and have a 0.473" rim

---------------------------------

7.62 x 39 and 6.5G are 45k and 52k/58k on pressure and 0.447" rim diameter

https://en.wikipedia.org/wiki/7.62%C3%9739mm

https://en.wikipedia.org/wiki/6.5mm_Grendel

---------------------------------

The .223/5.56 AR bolt has a 0.378" boltface and 55k PSI rating.

Once you start opening up the boltface to 0.447" or 0.473" you have to reduce the pressure because less strength remains in the bolt after metal is removed.

This is why hot-rodding a Socom round is a NO GO for an AR, but completely acceptable for a bolt gun (like mine)... and why x39 and 6.5G bolt failures are so common in AR-15s.

I am sure most everybody knew this already, but I am slow in the head...