Lyman 358311 in Ruger GP100

[handloder]

This is an OAL question. In the beginning, Lyman cast bullet manuals have specified an OAL of 1.590" for this boolit in the .357 Mag. I cannot get this OAL without seating the boolit fully over the driving band. When I back off the seating die for the mouth of the case to just touch the bottom of the driving band (so there's room for the roll crimp), the OAL is 1.655"! How do you reconcile this data?? Could my mold be casting boolits this much out of specification? Here is some additional data: boolit weight 162gr from wheelweights, boolit length 0.730" as cast, Ruger GP100 chamber length 1.665" with a Blaser case in the chamber (Starline brass gave 1.662" i.e. case rim 0.003" thinner than the Blaser case). How are we to interpret the data in a reputable loading manual when our bench results are so far off? Does this traditional Lyman data reflect a VERY wide variation in .357 chamber lengths over the decades of .357 revolver production? If so, how should the reloader modify OAL to best match his cylinder length dimensions against the location of the crimping groove?

[Lefty SRH]

I have asked the same question. I shoot a lot of 358311's for competition in a GP100. I honestly think you are supposed to crimp over the front driving band. I recently noticed that the front band is smaller than the rest, its only .354". Maybe that why the front band is small, so you can crimp over it for loading the .357 mag.

I said I shoot a lot of the 358311's, its for IDPA and I load them as .38spl's.

[fecmech]

That bullet was designed for the .38 spl. long before the .357 mag and has similar problems to the 358429 (Keith)swc as far as oal. I load the 358429 with a taper crimp on the front drive band to 1.0638 for my GP100. Lymans load data is for the shorter oal so you will incur no pressure problems going longer. Your loading dies should provide enough bullet pull to prevent the bullets from moving under recoil in the .357.

[Alan]

If there is room in the cylinder, crimp in the crimp groove. This give you a bit of headroom if you want to load it up to their top velocities. I didn't twig to the OAL issue when I first started loading Lyman #358429, and just used the recommended load of WW 296 with the recommended load. For the first 5 loadings in new brass, it made a LOT of steam, and was scary accurate in my NMBH. After 5 they went in to the plinker/practice bin, because velocity had dropped to the point that POI had gone up a couple of inches at 25 yards.

[handloder]

It looks like fecmech is closest to the truth. I have some Western .38 Special factory ammo from the late 1950s and they have OAL of 1.530". This is the nickel plated brass, copper clad ammo (looks just like 358311) of yesteryear. In my S&W Combat Masterpiece, this factory ammo has plenty of room left over after chambering. Is anyone using 358242 in 120gr flavor for IDPA?

[Lefty SRH]

If the 358242 is a Lyman mold I'd like to see it. Lyman doesn't list it on their website.

[kenyerian]

http://castboolits.gunloads.com/showthread.php?t=69390 This link discusses the 358242