I have already loaded up some cartridges for my Ruger M77 MkII Ultra Light in .257 Roberts with 100gr bullets and IMR 4350. I am looking at getting another powder to try a different burn rate. The 4350 is a pretty slow powder and I am wondering how much faster to go.

I know that for a short 20" barrel a much faster powder would probably get me more speed but I am also wondering if the faster more violent powder would cause more vibration problems with the thin light weight barrel. Do thin barrels benefit from faster or slower powders?

Barrel length may have an influence on the powder burn rate you choose, but I doubt anybody can predict a relationship between barrel contour and powder burn rate. Predicting how and where you may find a "vibration node" (and thus decent accuracy) is probably beyond normal ballistics "science".

I have used VV N160 for the .257 Roberts with 110 grs bullets in a 22" barrel. I doubt you want to go for a massively faster powder. The Hodgdon reloading site predicts pretty decent velocities with powders such as H414 and H380. For me they'd be potential candidates if you want to try something faster than IMR4350.

- mike

Hey Mort
My gal has the identical rifle to yours and hands down the best powder we have ever shot through it is IMR-4064.
With 100 grain Sierra's we worked up to a max load and it shot better the more powder we added. It is now turning in nice 3 shot .5 to .75 groups at 100 yards.
This rifle is bone stock, no bedding or trigger alterations at all with a 3-9 Leupold compact on top.
Good luck with your rifle!

The general agreement is the powders that preform best in long barrels also give best velocities in a shorter one. The best bet is to see what is reported to work best in your manuals and try the ones they found giving the highest velocities. Accuracy is a crap shoot. The load that works best in my rifle won`t always work well in yours. There are too many variations in bores, chambers, throats, bedding,ect to say this powder/bullet is the best. Try bullets known to be accurate on average and match them with a powder that gives the velocity you want and you should find one that shoots to your liking.

Thanks Folks! IMR-4064, H414 and H380 are powders I have been thinking about. H414 is pretty close to IMR 4350 so I think I will go with either IMR-4064 or H380.

Every bbl. is diff. so I don't think one can say if this or that powder works "best". I have a very light bbl. on my 280 & it thrives on slower powders, but that's my bbl. BTW, faster pwoders may burn a bit more completely in shorter bbls. but they wil not beat ta slower pwoder. You will get more muzzle blast though.