What caliber (not cartridge) is best for short barreled rifles when shooting heavy bullets?

[Weldor]

Your chrono must be way off or something. M80 ball from a 16" is around 2700 FPS.

It’s a labradar. Have you shot it or just reading?

 

[HandgunHTR]

Can I ask someone who knows this stuff well about 7mm-08 specifically? Getting one currently at 20” cut and threaded for suppressor. Have asked for 18” from gunsmith, but would 16” make sense if it would always be suppressed and I’m planning to shoot bullets in the 139/140gn size? I don’t currently hand load but have an option to work one up, and it would probably be a 160gn TMK. Also, it’s a 1:9.5” twist. Thx

I have an 18" Encore barrel in 7-08. I shoot it suppressed with a Harvester EVO. With Starline brass, Varget, and a 120 grain Nosler BT, I am getting around 2725 fps. For the 139 grain SST, I am at 2675.
Not sure the 9.5 twist will stabilize the 160s at that slow of a speed. There are twist calculators that can tell you, or you could just shoot them and see.

 

[Packmansion]

20" 6.5 creedmoor is getting 140 eldm and 143 eldx right at 2700 fps. Not sure you need much more than that. Ad a suppressor or break and you're recoil is basically non existent.

 

[Alaska92]

https://www.frfrogspad.com/intballi.htm

Expansion ratio is a topic worthy of learning.

 

[Alaska92]

Outside of the really big boomers, it seems there would be an ideal intersection of powder burn rate, bore vs powder charge, and barrel length?

Seems like somebody oughta be able to math this out. I.e. stuff that has a bore/capacity ratio of X and best performance with powder Y will do best in barrel length Z.

You’re on to something.

 

[danhuntingmi]

I guess I'd disagree with many of the assumptions in the OP. In the same case, smaller caliper bullets use slower burning powder not faster, contrary to what OP states. Smaller caliper bullets also rely more on velocity for energy.

There's a reason why the short barrel optimized intermediate rifle cartridge is .30 cal (.300 blackout) vs 22 caliper (5.56). You are looking for larger caliper bullets, not smaller.

 

[danhuntingmi]

To run heavy for caliber bullets, you would need to run slower burn rate powders to get to a velocity that would keep a 190+ grain bullet to 1800 fps at 440 yards. Nosler shows a max load of 2000 MR getting 2625 fps in a 24" barrel take 200 fps off that for the 8" barrel loss and you are at 2425 which is not much above the minimum requirement to make 1800 fps at 440 yards. The 308 Winchester might not be the right cartridge for the 308 caliber bullets in a short barrel. There may be some powder that would make it work.

Jay

The .308 works just fine in a short barrel and, while there is overlap in powders, generally uses faster (not slower) burning powders than the 6.5/6mm creedmoore and 243 Winchester.

The reason the .223 uses faster burning powder than the .308 is the smaller case, not the smaller caliper as you claim. For instance, the similar case .300 blackout can be loaded with H110 which is way too fast to load .223.

You also appear confounded between larger 'caliper' and heavy for caliper bullet weight. Some people may (or may not) load heavier bullets per caliper with slower burning powder, but this is a different issue entirely.