357 Mag reloaders

[Major Kettle Hill]

Hello to reloaders!
    Recently attempted reloads of 357 Mag
                     5.9 grains Bullseye powder
                     158 grain lead RNFP
                     Winchester Large pistol primer
At 7 yards several of the paper punches were enlongated as if the bullet had entered sideways. Thoughts?  Considering different powder, or increase # grains of powder, or do I need Mag primers?  Oh these were fired from six inch barrel pistol.

[Tombstone]

Seems like a lot of Bullseye. What is the volley they are publishing in the book. I am only using 5.7 gr of TiteGroup in a 45 and it is a lot slower burning powder.

[Sheriff Langston]

My Lyman book says starting load of BE powder at 4.9 and max at 6.9 with a 160 gr. bullet.   Don't know if it has an impact on the sideways issue however 357 mag calls for Small Pistol Magnum primers - not Large Pistol.

Sheriff Langston.

[Tombstone]

The only thing that I know of the primer making a difference is if you miss one with powder, the mag will more than likely push the lead out of the barrel and if you are really lucky it will even hit the target
Bullets will wobble coming out of the barrel. The higher the velocity the more wobble before it stabilizes. It may look different 15 yard out.  You need to crono those loads and see what the velocity actually is. You may also want to start near the bottom of the suggested load and see if that changes anything.

[Jackalope]

Bullseye is generally considered a little too fast-burning for .357 Magnums.  And large pistol primers will not easily fit into .357 cartridges!

A fairly large charge of fast burning powder would probably not be the sole cause of bullet instability.  I would first look into bullet fit, hardness, lubrication and condition of the cylinder throats and barrel.  Those variables can add up to result in key-hole shaped bullet holes.  I would be interested to hear what the paper targets look like from 15 or 25 yards. (Any key holes?  What's the groups size?  Chrono data can be helpful, too.)

You certainly don't need magnum primers to ignite Bullseye unless it's 30 below!

p.s.  My old Lyman reloading manual lists 4.5 grains of Bullseye as maximum with a 158 grain lead bullet.