AR Sponsor
Posted: 10/29/2025 5:52:52 PM EDT
| Question: Would carbine gas function reliably in a super-only 14.5" or 16" dedicated upper? |
|
There isn’t much case volume after a long bullet is inserted into a 338 ARC brass. I shoot 6.5 Grendel and long bullets sit deeper into the case intruding on the volume of available powder space. Depending on the bullet of choice like a short 85 grain Sierra Varmint you’re getting a compressed max load of Accurate 2520 of 33.9 grains. Same bullet with Tac powder max charge is 32.2 grains compressed. A 95 grain V-Max 6.5 Grendel load with A2520 max charge 32.5 grains compressed. A max charge of A2520 in the 6.5 Grendel with 123 grain SMK is 29.6 compressed. The Hodgon load data for a 160 grain Barnes TTSX-FB max load is 26.8 grains compressed with fast powder CFE BLK a Supersonic 338 ARC. I’d be afraid with a mid-length gas barrel you couldn’t get enough gas for a subsonic to be reliable. The main purpose of the 338 ARC is subsonic. There are better supersonic cartridges IMHO. Hodgdon list a max load of A2200 with a 300 grain HPBT subsonic of 15.2 grains at 35,800 PSI. The supersonic loads are 46,000 to 51,000 PSI. That is a big variation in pressure with powders that can be temperature sensitive. I’m skeptical about 338 ARC in a midlength gas being reliable in varying temperatures especially cold temperatures. You might configure a supersonic midlength to be reliable but will it be reliable with subsonic without significant changes to buffer or gas setting. I bet Hornady has the test data and might be worth asking them. |
Joined:
Aug 2023
Posts:
9148
EE: 0% (0)
NC, USA
Joined:
Aug 2023
Posts:
9152
EE: 0% (0)
NC, USA
|
Originally Posted By panthermark: If supers only, why not 300 Ham'r or 350 Legend or another big bore? Neck a 400 legend down for 350 legend bullets . Kind of the 375socom to the 458socom . 9x42 * plus the 9mm A2 fh would fit Closer to 35 remington ? |
AR Sponsor