Powder speed....308 Win, 20' tube

stovepipe · Posted: Thu Sep 22, 2011 7:28 am Post subject: Powder speed....308 Win, 20' tube

20" heavy tube, 1/10" twist...looks like a rolling pin.

I think I'm going to start with a 168gr SMK. I could go bigger but, why at this loads speeds. Hearing good things on the 150gr too!

Any special powder speed considerations with such a short tube? What's in yer databook? Razz

chambered221

Don't you know Varget is the only powder available for a 308 !!!

I always liked W748 and IMR4064 ........ pre Varget era

RePete

The 175's do a great job with a 1:10 twist.

I only use RL15.

Dawgdad

all of the above...

stovepipe

Thanks boys.

So- am I overthinking this 20" barrel thingy? Slower stuff should be OK with the little tube?

It looks like a rolling pin, how the hecks the charge get enough room to burn in there! Laughing

fnuser

if you want to play around, my speer #13 lists load for the 14" tubes but both the berger and smk go on a charge of rl15.

stovepipe

Excellent- thanks FN...

Wanna by a premium Cyclocross bike for cheap???

Elvis

PM coming your way.

stovepipe

Got it thanks El VEEE!

Gonna be a busy boy on the bench here soon! Laughing

fnuser

It is already hard enough to explain the difference between the one I got and the roadbike to my missus. It is kinda like trying to explain having a .320 Howell and a 30-"06.

SingleShotLover

Just focus on the powder that works best for your cartridge/bullet combination. Smokeless powder burns so quickly that it is consumed in the first couple inches of the barrel. The rest of the job is performed by the pressure thus created and its duration against the base of the bullet. Shorter barrel-shorterer push-less velocity. Longer barrel-longer push-more velocity (within reason of course). Since most rifles give up between 25 and 35 fps per inch at most, it really isn't enough to obsess on.

Good luck and good shooting!

stovepipe

Thanks FN, gotta buyer on the hook now.

Copy SSL. Thank you.

stovepipe

I was on the Sierra site looking at the BC for the 168 and 175 SMK. Big jump in BC for the 175. I think I'll make that my first choice for load testing, it's longer than the 168 and I'd like to develop a round that'll fit in the mag but I wont have a problem single shooting like Kabong if the chamber's huge to get closer to the lands so- gonna make a dummy round w/ a 200gr SMK and see how long the chamber/free bore is...so we'll see. 6 more painful days to go till its outta jail....then I'm taking it to the range with 3 boxes of Fed GMM 168gr. Not a bad price either @ 20$/box so...can't wait!

Kinda suprised Phill aint gottten back to me with the "accuracy" load data sheets then normally send, he's prolly swamped as usual. If any of ya'lls gots give me a shout and e-mail/fax me some copies if you have it handy maybe?

SyberShooter · Member Joined: Jul 23, 2010 Posts: 93 Location: Arizona

Somewhere along the line I think I read the optimal length for 308 to ensure complete powder burn was 18" or 19". There are a lot of good powders for that cartridge. Among them are Varget, 2460, RE15, W-846 and a bunch that start with H- or IMR-

Elvis

Remington mohawk
browning BLR
to name just 2 that would argue with that statement SyberShooter.