.357 ruger gp100 with missouri action bullets

[cbr]

Hi. I just got a Ruger GP100 in .357 magnum, and am anxious to try to harvest a doe with it (already got my buck). I have cast for a couple .38's with good luck, but I was afraid my .38 bullets would be too soft for the .357 so I purchased a box of Missouri Bullet 158 grain swc "Action" bullets. They say they are brinell 18, optimized for magnum velocities. Well, have tried running them with unique, starting at 6 grains, and have worked up to 6.7 grains, which my Lee book shows is close to max. They shoot well, but I am getting quite a bit of leading right in front of the forcing cone. I just spent the last hour scrubbing all the lead out of my barrel, and now have it spotless again. I was wondering if I should try to push them even harder, if that would make them bump up to fit the forcing cone better? This is my first magnum caliber. I slugged my bore and cylinder, its .357, and the cylinders are .357 also. The missouri bullets are .358. Should I try my softer cast 158 grain lee rnfp bullets or would they be too soft for the .357. I want to try to push these to around 1200 fps or so to make a good deer load. I have unique, titegroup, #2, and 231 powder on hand. Any suggestions? Im kind of in a hurry to work up a good load because deer seasons soon over! Thanks

[mpmarty]

Harder aint always better. Try the other boolits and see what you get.

[geargnasher]

+1 Marty.


CBR:

I have the same gun and it leaded so badly I couldn't shoot a cylinder full and keep them all on the paper at 15 yards. Problem with mine was the cylinder throats were all .356" and the bore is .357". This problem was, like yours, exacerbated by harder boolits. Bought a .3580"chucking reamer at one of the online machine tool outlets, built up masking tape as a centering guide, and reamed all cylinders out from the back side. light polish with wet 400 then 600 and a split dowel made them pretty. Now I can shoot air-cooled WW to (estimate) 1325 fps with little if any leading.

Also on the Ruger, check for a restriction at the forcing cone where the barrel threads into the frame, they are notorious for crushing down the barrel at that point as much as .0015". If yours has this problem consider firelapping.

One more thing, I just found out what so many others knew, cast in the .357 Magnum LOVES Alliant 2400, and LOTS of it. I get outstanding accuracy at published maximums, but work yours up slowly.

Good luck!

Gear

[lylejb]

I had leading at the forcing cone / cyl gap with commercial cast as well. The solution was a softer boolit. I now use 2/3 WW 1/3 pure, air cooled, and sized .359 (my cyl throats are 3@.358, 3@.3585) these are about BHN 10. I've run these from about 650fps to about 1200 fps without a problem.

What alloy / hardness are your 38 boolits?

Try them, you might be suprised:D

[cbr]

Thanks for the quick replies guys. My .38 bullets are just straight air cooled wheel weights with some tin added. I will give them a try. I guess Im just trying to cheat and get some advise from you pros on here to save some time. One more question, would I have better luck with a slower powder like 2400 than with unique? I dont have any, but might pick some up later in the week.

[fecmech]

Buy some 296,H110 or 2400 and I think you will have better luck getting 1200-1300 fps with minimal leading. The powders you list are all too fast for where you want to go.

[Bullshop]

Hard lube? Some lubes are formulated to enhance shooting characteristics and some are to keep automated machines running.
Maybe the boolits are OK but need a lube made for shooting.
BIC/BS

[lwknight]

I was getting build up around the cylinder mouth from shooting 38spl cases in my gp-100 too.
I tried what by brother-in-law did with his. He used an old bore brush with some #0000 steel wool with jewelers rouge on a drill and polished the cylinder mouths. He said it cured his lead problem. I have not tested mine enough as of yet.

In my case the cylinder mouth excepts a 357 sized boolit with thumb pressure and the bore slugged .356 and I had been shooting 358 boolits.
My next test will be using 357 boolits.

[lurch]

cbr,

You got some good advice above.

ACWW are definitely capable of full tilt loads in the 357 IF the boolit fits the gun. I get my best results (in a S&W 586 though) using 2400 for the heavy loads with ACWW + ~2% tin. If your throats are truly all 0.357 and the barrel groove diameter is also, 0.358" boolits should be just fine in theory. Going to the softer boolit may be your ticket. Each gun likes what it likes though...

[Bullshop Junior]

I really don't like the lube that factory Wannabee boolits come with.
I think that is probobly your problem

[geargnasher]

I missed that the cylinder throats were .357. That, combined with too-hard commercial boolits and too fast a powder and inadequate lube as has been mentioned. I have never had luck getting same-sized cylinder/groove dimensions to work very well. Generally, a revolver does better with at least .001" oversized heading up the forcing cone, helps achieve obturation and thus reduces or eliminates blow-by and gas cutting which is the major cause of leading.

Fit, as Bret4207 has pointed out many times, is King. If you get a good seal from fit, the factors of lube and alloy hardness diminish in importance and you have a lot more leeway with them.

Gear

[GP100man]

My GP`s get nervous when the 2400 gets low!!!!

[randyrat]

My son's GP100 had 4 out of 6 throats were real tight. I had more lead in the bore than down range. I reamed untill all cylinders were the same. Now i can push a .358 cast through all throats with the same finger pressure....no leading

It took me a while because i use 400 grit and 600 grit paper and a slit dowel.

One more thing, i tried Unique with no luck.....2400 towards the heavy side works good. I still would like to try unique or some of the fast pistol powers, but it's going to take a different bullet and some tinkering. Why, it's not my gun,,,, I'll just tell my son the gun only works with 2400....

[Harry O]

I have the same gun and use 358156-GC bullets in it. No problems with leading and accuracy is good. I have never had much luck with plain base bullets (even at Bhn 18) in magnums or rifle loads at similar pressures. By downloading the .357 Magnum, I can use plain base bullets.

My own personal cutoff point is 22,000 to 25,000psi max for plain base. 30,000 to 35,000psi max for GC. Anything over 35,000 is jacketed. I know that others on this site can and have gone higher, but this greatly reduces the aggravation (and lead scrubbing) for me.

[cbr]

Well, thanks for you help guys. I stopped by the local gunshop to pick up some 2400, but they were out, so I asked for #9, but they were out of that too. They suggested H110 so I picked up a pound of that. I just finished firing some of the Missouri Bullets with 12 grains of H110 and 13 grains of H110. They shot great and no leading with the 12 grain load, but it looked like quite a bit of unburnt powder in the barrel. The 13 grain load had a few very minor steaks of lead, but not enough to bother me, and seemed much cleaner with less unburnt powder. do I need a magnum primer with H110? I think Im going to load up some at 13.5 grains and see how they shoot. Thanks again!

[lurch]

H110 will generally do better with a magnum primer IMO.