Ruger gp100 problem (my fault)


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Tom_AZ
June 9, 2014, 02:27 PM
So I got the brilliant idea to slug the bore and cylinder on my 4" stainless gp100 so I could get the proper sizing die for my lubrisizer. Well I got the necessary measurements, but in the process I messed up. When I was done the cylinder won't close easily. If you force it closed, the cylinder won't turn if you cock the hammer or pull the trigger for double action firing.

I am guessing that I bent something when I was trying to tap the lead slug through the cylinder.

So my question is do I attempt to have a local gunsmith look at it or do I send it back to Ruger. Is this a really expensive mistake?

Help!

Tom

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BBBBill
June 9, 2014, 02:31 PM
Did you shave a little lead off between the face of the cylinder and forcing cone?

Jim K
June 9, 2014, 02:35 PM
First, make absolutely sure you didn't shave some lead in the process and a piece of lead is between the crane and the frame, under the extractor, or somewhere else that it can tie up the cylinder. Check, then double check. Then check again.

If it does appear that the crane is bent (it is hard to see what else it could be), then IMHO it is a problem for the factory.

I guess it is too late, but you don't involve the cylinder in slugging the bore of a revolver; in fact it is better to remove the crane and cylinder altogether. Then you insert the slug in the muzzle and use a brass or aluminum rod close to bore diameter to force the slug through the barrel.

Jim

Tom_AZ
June 9, 2014, 02:36 PM
I slugged the bore and cylinder separately.

Tom_AZ
June 9, 2014, 02:37 PM
Jim, thanks. I will double and triple check. I was surprised because I was tapping with a 12 ounce rubber/plastic mallet. The crane is massive. That's why I was so surprised.

Tom_AZ
June 9, 2014, 02:39 PM
To clarify, I opened the cylinder, placed the face on a block of wood and slugged the chambers separate from the bore.

Jim K
June 9, 2014, 03:42 PM
I am not sure I see any point in slugging the chamber unless there is something very wrong that can't be detected by a caliper. In fact, I never saw much point in slugging a barrel anyway except when the caliber is unknown and the bore dimension is needed. I just sized .38 Special/.357 to .357 and let it go at that, and never saw any reason to change things. In other words, you may be over-worrying about that cylinder and barrel.

It would take only a light tap to drive a .360 slug through a .357 cylinder, so I don't see how you could knock the cylinder or crane out of alignment that way. Anyway, have you checked for lead?

Jim

BBBBill
June 9, 2014, 05:59 PM
It is deceptively easy to tweak the yoke (crane) out of alignment with the frame. The tools to check and correct that are readily available and not difficult to use at all, if you are so inclined. Of course the simple thing is ship it back to Ruger.

Tom_AZ
June 9, 2014, 11:06 PM
The only reason I slugged the barrel is because I'm getting into casting and from everything I've read and been told by very knowledgeable people, knowing cylinder throat and bore diameter is very important for bullet sizing.


Anyways, thanks for the tips. I'll give it a good looking over and cleaning.

rcmodel
June 9, 2014, 11:35 PM
You did the right thing by slugging the chamber throats, as well as the bore.

You just did it wrong by leaving the cylinder attached to the gun while doing it.
And sprung the crane, or bent the ejector rod.

The reason for slugging the chamber throats?
One or more, or all the chamber throats can often be found that are smaller then bore diameter.

And that will always lead to bore leading and accuracy problems.
No matter what bullet diameter you try to use.

rc

Jim K
June 10, 2014, 12:33 AM
Just curious, but how is slugging the chamber throats better than just measuring them with a caliper?

Jim

rcmodel
June 10, 2014, 01:00 AM
Because you can't accurately measure them with a caliper.

The only accurate way to measure chamber throats, or any internal round hole is by slugging them and measuring the slugs.

Or, using a set of precision ground steel plug gages that very few people can afford for one job.

rc

Tom_AZ
June 10, 2014, 02:19 AM
Rcmodel, that is the exact advice I was following. My barrel slugging of my super blackhawk went well, the gp100 is where I ran into trouble. And I did gain very useful data. The blackhawk throats all slugged .432 with a .430 barrel. The gp slugged .359 throats and .357 barrel

rcmodel
June 10, 2014, 02:23 AM
Then all is well.
Except for the 'Don't Work Now' part! :banghead:

rc

Kp321
June 10, 2014, 11:27 AM
+1 on the hardened gauge pins. I bought a full set on eBay a few years ago and use them for all types of bore gauging. The full set was not outrageously expensive but individual ones are available for a few bucks each.

BBBBill
June 10, 2014, 01:52 PM
As rcmodel noted, the mistake was leaving the cylinder installed while gaging. Revolvers are tough, but pressing or hammering on them in any way with the yoke/crane still attached to the frame will bend the yoke. Same reason that the Hollywood flip is discouraged. It only takes a tiny amount of bend to significantly affect cylinder alignment.

beag_nut
June 10, 2014, 04:03 PM
Because you can't accurately measure them with a caliper.

The only accurate way to measure chamber throats, or any internal round hole is by slugging them and measuring the slugs.

Or, using a set of precision ground steel plug gages that very few people can afford for one job.

rc
A few points:
One doesn't need a full set of plug gages. An assortment of Class Z gages, with .0005 inch increments, such as .3570", .3575", etc., goes for $3.37 each, from supremely trustworthy suppliers such as McMaster Carr. Thus, one could get five gages for about $20, much cheaper than the repair to the subject revolver.
Another option is a small-hole gauge, range .300" to .400", which is adjustable and more than adequately accurate for the required application, for $40.
http://www.mcmaster.com/#catalog/120/2272/=scml1s
For that gauge, one uses a micrometer, NEVER a caliper. (A caliper only gets one into the ball park)
Also, "tapping", with a hammer or similar, is NOT the best way to slug. Rather, a C-clamp or similar, with appropriate cobbled-up wood or plastic shims, is the better way to remove a stuck slug from a cylinder. Better to treat the problem as a potential $500 cost, than to whale away and then spend that money for someone else to fix it.

Tom_AZ
June 10, 2014, 06:11 PM
Good tips, thanks

Tom_AZ
July 1, 2014, 10:32 PM
Update, sent the gun back to Ruger. The note they included said that they fixed the cylinder and crane. No charge! Great customer service!

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