Best powder for 20" encore 7mm-08?

yukon100jack

I have a 20" encore barrel that has been shortened and recrowned by MGM. It shoots OK but the tack-driving, sub-moa group is hard to achieve consitently. So far I have been using IMR 4895 and IMR 4350 powders with about five different bullets ranging from 120 to 140 grains. Does the shorter barrel require a faster burning powder than either of these? Any other suggestions? Thanks!

Rocky Raab

No. The optimum powder for a cartridge is the same, regardless of barrel length. The barrel length will cost you some velocity, but you'll still get the most possible by using the optimum powder.

Note that the short barrel will result in higher blast, because the residual pressure will be higher at bullet exit than it would be from a longer barrel - but without that high pressure, you'd be getting substantially lower speed, too.

20gabob

With the 120 gr you might try h414 from 45 to 50 grs or h335 from 39.5 to 44 grs. Also h380 from 42 to 47 grs. for 139/140 gr bullet try h414 43 to 48 gr, h380 41 to 46 gr, or h335 37 to 41 grs. I have always found a very accurate load for the 7/08 somewhere in those powder ranges and all it takes is a little loading and shooting to work it our foe yourself. plus the powders all come out real accurate from my powder measure once it's set up to throw them, just a hint as ball type powders normally measure more accurately than stick for me anyway.

20gabob

With the 120 gr bullet, i suggest you try h414 41to 45 grs, h335 40 to 44 grs, or h380 42.5 to 47 grs. For the 139/140 gr bullet h414 43.5 to 48 grs, h380 41.5 to46 grs, or h335 37 to 41 grs. I have always been able to find a super accurate load somewhere in that range of powderweights for the 7/08. Always easy to adjust powder measure to throw very accurate charges for "ball" type powders much more so than stick powders. MY PERSONAL OPINION.

Rocky Raab

Those are fine loads, bob. In a short barrel, however, spherical powders tend to produce humongous fireballs. That's because they produce a lot more unconsumed flammable gasses AND unless they are formulated for military use, do not contain anti-flash additives.

He'll get a lot less flash and bang with extruded powders, which are often single-base. Good choices in the 7-08 would be RL-15, 17 or 19, IMR4320, 4064, or 4350, Varget, or H4350. Choice depending on bullet weight - and per a good reloading manual.

nononsense

yukon100jack,

Please check your e-mail.


Best.

Mobuck

I just got a new Wby Vanguard Compact Carbine with the 20" barrel and figured I'd start with IMR 4064. I also have H414 and will compare the muzzle flash/blast between the two. Also have a pound of AA2520 left over from another project but don't know if I'll mess with it or not. My previous uses of H414 were with 24" barrels so I haven't experienced the flash problem much.

Rocky Raab

Rocky rubs his crystal ball (No, wait. That didn't sound exactly right ...)

Rocky PREDICTS (whew!) that you'll see a large fireball with 414 and a truly spectacular one with AA2520.

Mobuck

I don't want to set the deer blind on fire.

yukon100jack

SO far the best load is with Varget and 139 grain hornady interlock SPBT @2700 feet per second. 5 shots will usually do an inch or less, sometimes just over that. The Encore is extremely light and short with this barrel. A crimp does help keep the loads consistent too. Without a crimp there is more deviation in FPS and in the size of the groups.