View Full Version : Revolver Barrel Size to Chamber Size?
09-02-2005, 11:29 AM
My GP100-357 measures .357" when I drive a swaged bullet through the end of the cylinder (all six seem to be the same) but when I drive a swaged bullet down from the muzzle through the forcing cone I come up with .355". I don't know if the barrel is that tight or just the forcing cone. Does that sound right? The gun has always been fairly accurate with most cast boolits but has a lot of rounds through it and I thought it was about half wore out because of a .008" cylinder-barrel gap.
09-02-2005, 02:07 PM
Sounds like it is just right.
09-02-2005, 02:26 PM
.355 sounds small to me. Is the bore clean? Do you feel the force increase as you put it down the barrel?
Try making an index mark on the nose of the boolit before you send it throught the barrel. When it comes out the forcing cone, pick it up and put it through again with the same index. Sometimes this gives a better feel for what is going on because the boolit is now fully sized. May not work in rifle barrels because of variations in the twist and groove, but in a 4-6" tube on a revolver it just may tell you something.
09-03-2005, 04:09 AM
............An .008" barrel-cylinder gap is a lot too. Should be half that. I'm not much of a pistol guru but I think wear would appear first (or in some order) like cylinder lockup issues -timing-, forcing cone erosion especially in magnums, and recoil issues such as your bbl-cyl gap.
09-03-2005, 05:51 AM
I would suspect the bore being closer to .356. If you drove a slug all the way through and there is a little restriction where the barrel screws into the frame, you will have a smaller reading. Fire lapping will get rid of any restriction.
The gun should shoot just fine with .357 boolits. The cylinder gap is within factory limits, many came that way. As long as there is no wear and cylinder end shake you will only loose a little velocity and get a little more blast. These guns were not built for target accuracy but still shoot good.
I prevent wear by using STP or RCBS case lube on the front bearing, pin and ratchet. I would never fire any of my revolvers without the lube. I have no ratchet wear or end shake on my SBH and have just passed 56,400 rounds. I just shot some 4" to 5" groups with it at 200 yd's.
09-03-2005, 01:08 PM
I suspect the barrel is not as tight as the .355" but I haven't tried to drive a slug down to the forcing cone then back out yet. Is there any way to open up the forcing cone a little or should I let well enough alone? The gun is over ten years old and has been shot a lot but with all kinds of loads from 38spl to full .357, but a lot have been cast of some kind. The cylinder gap is a little much and the cylinder has a little play front to back but I don't think it was all the tight when I first bought it new, I wish I had checked it. Thanks for the advice, I really ought to buy a single action as that's the way I shoot this one.
edit: The 6" barrel was clean when I checked it except for some oil I put in. I've never noticed any timing issues with it. Does it start to spit a little lead if that's off or will a big gap do that too?
09-03-2005, 05:33 PM
I wouldn't do a thing but keep shooting it. Keep it lubed and you won't have any wear. A tiny bit of end shake is OK. It won't spit lead unless the timing is off. You might get some powder grains spray out from the cylinder gap with a slow powder but you don't put your hand there anyway, do you?
It sounds like a fun gun to shoot, forget all the other stuff.
09-04-2005, 09:09 PM
I WISH I COULD SHOOT THAT GOOD, EVEN OFF A BENCH.
I like the rugers, & I've shot the S&W N,K,&L frams, & the colt python.
Take care of that gun & your lucky kids will be shooting it when you are in the happy hunting grounds.
It wouldn't be heaven if we couldn't hunt & shoot right?
09-05-2005, 07:17 AM
I used to have perfect vision and was able to see the sights and target perfectly. Now it is getting real hard. I am 68 and even with a scope I have problems seeing. I got new glasses and can't shoot with them yet but from wearing them, my old glasses don't work either. Can't afford special glasses. Plus I shake more now. Old age is hell on shooting!
09-05-2005, 08:08 AM
First of all, I know very little about Ruger DA sixguns, but do have several SAs, but in general let me add
1. The standard Colt groove diamter for their 38/357 sixguns was .354-355 and produced great accuracy. I have also seen several Smiths that small although most run .357 in the grooves. The point being that a .355 barrel won't hurt anything.
2. I have measured a few Ruger cylinder throats and they all measure .357 - .358
3. Lead slugs will have some "spring back" after they have been compressed, so you can add .0005 to .001 depending on how it was done, and the type of metal. Not all lead is 100% lead.
4. I have had barrels measure a full .001 - .002 larger after they were cleaned of powder and metal fouling. The same applies for cylinder throats
5. .008 is at the very edge of acceptable barrel/cylinder gap. .002 - .004 would be better, but at .008 is not worth the effort and money to set the barrel back and re-set the gap. You will just loose some velocity and get a larger flash bloom at that point.
6. Ruger's are not high dollar pistols and you get what you pay for
7. I don't think you have any problems..just shoot it and have fun!
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