How to Stretch 357 Cases?

[pcw907]

I have a problem with short cases in 357. I believe my accuracy was hurting with varying case lengths from 1.270 to 1.289 in my cast loads . I had sorted by length before loading to ensure correct bullet depth, but I believe the shorter OAL cartridges are causing the boolits to shear the sides a bit as they jump the chamber gap then enter the rifling. The rifle is a brand new Ruger 77/357 which was getting sub MOA groups with jacketed, but only 4 MOA groups with cast. It may get better as the gun gets broken in.

The only way to stretch the cases I can come up with is to shoot some hot jacketed in them to get some brass to flow in the chamber. I would like to get them all to 1.280-1.283.

Any other thoughts (besides be patient)?

[felix]

Case length is seldom the culprit. Instead, it's the amount of drag on the projectile that controls the initial powder burn. ... felix

[uscra112]

Only factor I can think of that would make case length an issue in your .357 is the variation of crimp due to case length. It makes a difference in my revolvers. Matters not much how long the cases are, just that they are all the same and that the die is adjusted for the right amount of crimp. I also find a significant difference when the cases are not all expanded to the same internal diameter. When I use "range brass" I have to sort with a plug gage to get a set that has uniform ID, after trimming for length and expanding.

Only way to stretch a case that I can think of, without making a set of draw dies, would be to fire it in a gun with excess headspace. Not a good plan, as all the stretch will take place near the head.

[357Mag]

PCW -

Howdy !


I'm not sayinz you need to.... or should:

One fer sher way ( excessive ) to obtain a .357Mag+ case length... would be to cut .357Max cases to whatever length you
sought.

This'd be $$$ and obcessing... in the extreme, but it's a valid answer.


With regards,
357Mag

[nanuk]

shorten Max, or 360 DW

[pcw907]

Roger. thanks for the advice everyone.

[Crusty Deary Ol'Coot]

AS Felix indicates, there is another problem here.

Crusty Deary Ol'Coot