GP100 snug cylinders?..

H

hearthethunder

Inactive
Okay, any smiths among us?
I have a GP100 that has just been broken in with jacketed rounds (200+) and have worked up some cast loads. Accuacy is not bad but I am wondering if I can do better. I have heard some talk on some other forums about NEW RUGERS and TIGHT CYLINDERS. So after my last cleaning I measured the throats of my cylinders with my dial type calipers. (best that I have) This is a .357 mag and I have shot a fair amount of 38 spl, so I am aware of the build-up that can occur. That cleaned up I tried dropping a 158g SWC round into the end of the cylinder...hmmm kind of tight. Measuring it I got .353"....to .355". Should I see about opening this up a bit? I am wondering if I am sqeezing these bulletts down and not getting all the grab that I can get on the rifling. With a clean barrel I am getting 2" groups at 15 yards using the 158g SWC in 357 mag with 7g of Unique with CCI500 regular primers. Lower loads are kind of opened up. With warmer loads is it possible to sqeeze the lead down and then pusing it hard enough, actually make the seal going down the barrel?
Appreciate you thoughts,
hearthethunder
 
hearthethunder - First of all welcome to TFL. Hope you enjoy it here as much as we do.

Since I have obviously have no idea of your experience with revolvers, please take this for what it's worth. I think you may be worrying a little too much about a non-problem. I would look first at my shooting technique, trigger control, load development, type/make of bullet, etc. all before I would start looking to find fault with the gun. I guess it's possible that a too tight cylinder mouth could cause accuracy problems, but it is unlikely that your GP-100 has tight cylinders. I measured my KGP-141 cylinder mouths and they are also .355 like yours and the accuracy is fine depending on the cartridge, my shooting skills, the time of day, the noise from nearby shooters, etc. ;)

I would bet good money that your groups will get smaller if you follow the advice about how to get to Carnegie Hall. :D
 
Thanks for the welcome....
I've hung out at the rugerforum for a bit and admit I am somewhat a newbee when it comes to handguns. (though I DO seem to have that bug too) But I have done the reloading thing now for a while and my concentration tends to be for accuracy. Recently I have seen posts (rugerforum) on this topic of tight cylinders.
I appreciate your comments and hope perhaps there might be someone that has experience improvement or could shed some light on why (if cylinders are typically tighter than barrel diameter) gun makers close up these openings like this. If you slug a barrel to find whether you should use a .358" or .359" sizing die, why would you want the bullet sqeezed down to say .355" before it even enters the barrel? Enlighten me guys! (not a wise crack) I know these forums are where the experts hang out and again I appreciate your help. This is how I learn!:confused:
 
OWN TWO

Don't worry, be happy..........

Not a "non-problem", but not yet a problem. Suggest more careful load development before worrying about throats. Use 357 cases, and pick mid-range (Unique/Universal Clays) powder. Finish ALL loads with heavy crimp using Redding Profile Crimp die.

For best accuracy try 140g XTP and H110.

(Every GP seems to have at least one Bullseye-quality load in it.)
 
Hearthethunder, welcolme from me 2.

I think your .353 chamber mouths are tight. I personally like around .356 on my target guns.......hopefully all the same. I had a Smith 686 with tight (.353) holes and it was a leadin/copper foulin mutha.

Friend has a .41mag that was a jewel but leaded badly and scattered the shots. He sluged the bore and reamed the chamber mouths to match....it became a clean shootin tack driver.

Another factor to consider. I have slugged the bores on a lot of duty weapons and found .357 bores that ranged from .354 to .359. If you have tight cylinder and loose barrel, the bullet is goin to take a flame beating on the way down. If both chamber and barrel are tight.......things will work just fine.

Sam.....follow me, I know a shortcut.
 
Welcome, hearthethunder.

I own two KGP-141s. I recommend you heed Weshoot, Mal and Sam's advice -- three of our real experts. As a comparative rookie, I respectfully suspect you may be searching for a problem that really does not exist. If your GP-100 is timing well with no hang-ups or roughness, is tight, and is hitting the target, than I suggest you concentrate on technique. In general, GP-100s have very well deserved reputations for high quality, outstanding reliability and durability, and excellent accuracy; it would not surprise me at all if your GP-100's performance fits this reputation without exception.
 
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Well, I'll be.....
Been shooting for 20 years and this has never occured to me.
Guess you learn something every day.

Damn, I knew I shouldn't have sold that M-17 32 Mag...ahhhhh! :o
 
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