[Master Blaster]

I recently acquired a 4" Lawman MKIII made in 1970 in perfect condition for $350 at a local shop where it had been put on consignment.

This is my first Colt DA revolver though I own many Smiths. I have an issue with mine, the cylinder is significantly shorter than on my Smiths, I had my favorite .357 magnum target ammo come uncrimped and creep slightly forward on this gun and tie up the cylinder.

The load is 4.0 grains of Trailboss a 158 grain LSWC remmington bullet with a magnum primer. I have loaded and fired 4,000+ of this load in the last year and a half with no problems, until I put them in my new Colt.

This is something that doesnt happen with my Smith 19, or even my J frame smiths, or my Ruger sp101, with the same load, a light target load BTW. That same load exhibits no creep in any of my other revolvers, this surprised me since its not a hard recoiling round, and the Lawman is a heavy steel gun.
I am putting a heavy roll crimp on this round.

[rcmodel]

I can't even imagine how that could happen in a full-size steel revolver with light target loads.

I'm baffled!

The only even remotely possible reason I can think of is excess end-shake in the cylinder.

That would give the relatively light cylinder enough backward recoil movement to work on the crimps a little bit each shot, maybe?

rc

[Steve C]

Colts definitely have a shorter cylinder than S&W's. Are you sure you are getting bullet creep or perhaps just getting a long round mixed in occasionally? If your OAL is right at the margin of fitting in the Colt and you get a slightly long one in the mix it could seem like the bullets are pulling when actually you've just encountered that particular round. With a heavy roll crimp on the rounds this is more likely than the bullets actually jumping the crimp.

[Claude Clay]

round nose rounds for my S&W 66 were a taste long in a friends trooper. HP's were flush and ok. rather than mess with set-back and potential pressure changes, i load FP's or HP's for him.

[243winxb]

I would guess that the ammo creeps slightly forward in all your guns. What makes the Colt different is the chamber thats cut into the cylinder. Its on the large side into the leade and offers no resistence to the bullet. And a short cylinder would be more noticible and jam the action faster as the bullet has less distance to travel to the forcing cone. Just a guess

[Iron Sight]

What 243winxb says.

The shorter cylinder allows the projectile and with crimp jump to lock up at the forcing cone entry.