Barrel shimm's, How long do your last?

[necchi]

I guess I'm not suprised, I've been expecting it, The shim on the 708 let loose today, it actually just dropped of when I picked up the barrel. Better now than in the field,
 This was a JB weld job, about 9 months an maybe 250 rounds or so. I'll try to find some Goop Super weld local for the next try, I don't think I'll bother ordering any, If I can't find it I'll just JB again.
 But what kind of longevity can a guy expect from any adhesive? Any Tip's-n-Tricks to help the stuff along? I do worry about a shim dropping off at an inoppertune time. (knock on wood)

[bikerbeans]

Neechi,

$64,000 question on the shims & JB Weld.  Here is my limited experience.

Shim on my 30-06 has about 200 rounds, mostly Lake City MilSurp, no problems to report

Shim on 45/70 22" barrel lasted less than 100 rounds before falling off.  Shot mostly handloads in the 25K to 35K range.

Shim on 45/120 32" lasted 10 rounds before removing itself.  Per Hodgdon all the loads < 28K pressure.  This particular gun the problem may be bad JB weld, because I mixed some more up and let it harden and it never did setup completely.  I tossed out the tubes of JB weld.

Resolved both 45 caliber barrel shims by playing musical receivers and now have good lockup w/o shims.  When/If the shim on the 30-06 fails I will try the Goop Super Weld.

BB

[S.E.Ak]

I just use a piece of tape of different types for the amount needed. Its easy to put on and can last twenty or more centerfire fireings and a redo in the field takes a minuet tops.

[petemi]

I shimmed one of my .357s with a piece of aluminum can and it lasted for quite a few hundred rounds.  It outlived its requirement.  I got other frames and swapped things around, so now, nothing has to be shimmed.

Pete

[gendoc]

I guess I'm not suprised, I've been expecting it, The shim on the 708 let loose today, it actually just dropped of when I picked up the barrel. Better now than in the field,
 This was a JB weld job, about 9 months an maybe 250 rounds or so. I'll try to find some Goop Super weld local for the next try, I don't think I'll bother ordering any, If I can't find it I'll just JB again.
 But what kind of longevity can a guy expect from any adhesive? Any Tip's-n-Tricks to help the stuff along? I do worry about a shim dropping off at an inoppertune time. (knock on wood)

thats the #1 reason i don't do shims!!  tried the super stuff and other stuff....i don't trust them.

if i get a barrel that don't play right..... it goes to someone else.

all of my frames have there respective barrels. and i have bought a few frames just for swapping.
most of the time i'm in luck....but there has been a few stubborn barrels that are gone now.

thats just me, 

[myarmor]

I utter gendocs post, I dislike shimming barrels as well and have several frames for mounting, though I know many have done it with good sucess.




-Aaron

[quickdtoo]

I've shimmed the better part of 2 dozen barrels, and have never had one fail, but I don't just insert a shim then fit the barrel, I cut the shim to fit so it has full contact on the hinge, not two points which is what you get if you put a shim in the existing pivot. You can't put a .004" shim in a pivot made to fit a .375" pin and expect it to fit the pin with full contact, you'll end up with a pivot that fits a .367" pin, the .375" pin will only make contact on two points within the pivot, it will work for a while, but all the pressure is on those two point which will eventually fail. I've got just less that 200 rounds thru the 500S&W, it's still nice and tight with no signs of failure using JB weld, if it ever fails, I'll use Super Weld which has over 3 times the compressive strength of JB, 36kpsi compared to 10.6kpsi. The 6.5x55 Swede and 260 Rem both have Super Weld shims installed, about 100 rounds thru the 260, and 60 thru the 6.5x55 so far.

Tim

[bikerbeans]

Tim,

How are you cutting the shim to fit?  Are you tapering the shim? 

thanks

BB

[quickdtoo]

It's all in the FAQs barrel fitting Tom, what you end up is a tapered shim. 

Tim

[bikerbeans]

Thanks Tim, I missed that one in the FAQs.

BB

[gendoc]

tim, i guess i should have said.... i had about 6 people shoot'n these shimmed barrels,
from grandkids to great grandmaw.  after about less than a hundred and some up to possibly a thousand rounds they failed. shoot'n for fun and hunting. without a shot meter installed..... i can't take that chance.
they all were shimmed correctly.
how many shots have your others been thru ?

[quickdtoo]

Most anywhere from 60-90, some more some less. Like I said, if the shim isn't cut to .375" after it's epoxied in place, it will fail sooner or later because the bearing surface is on two points across the pivot surface, not the entire surface area, and if it isn't cut to .375" to fit the pin, it isn't properly installed. I use a .375" end mill in the mini-mill to cut shims now, but that's not an option for most folks, I don't use pop cans for shims either, I use steel shim stock. 

Tim

[dw06]

 I used the accuglass bedding with the stainless steel powder you add in to do my 223 sometime in early 07. Its still tight after between 7-800 rounds, and being opened and closed almost every day as its my woods walking rifle that I grab when going for a walk..
 I'm happy enough with it that any Hand Rifle barrel I need to fit from now on, that's what I'll use. I'd like to see how it would do on say 7-08 on up to see how long it would last.

[Jimbo47]

I've got one barrel now that I shimmed using the JB weld and steel shim material, and it's on a smooth bore 20 gauge I converted to a slug gun by mounting a scope rail and cutting off the choke from the end of the barrel.

If it lasts a few hundred shots I'm okay with that and then I'll just redo it and start over and hope for another few hundred shots.

These are single shot rifles and fun guns, and if it should come down to a life or death matter I'll have something more realiable in my hands for sure!

[necchi]

 Well I think I know what happened with this one. I had originally fit it to frame #1 and all was well, but haveing a dickens of a time with the 308 and swapping that thing around on different frames and experimenting,,,,
 We finaly ended up with a time when both Dust and I where shooting.

 I put his 708 on frame #2 and it closed/locked up,,so off to the range we go. 30 rounds or so later and more swapping I noticed it was a bit loose in frame #1. It was a few weeks after that when the shim dropped off.
 It must have been too tight on frame #2, I never did check the latch fit, and it fired ok that day,,,but we must have squished the shim and it's adhesive during that range session.
 Not a big deal really, I'll just refit it proper to the #1 frame and keep it on there. The 308 goes on #2. Ya gotta do the experimentin', never know if ya don't try right?

[quickdtoo]

I forgot, I did have one shim fall off, or actually was removed by hot blue after Wayne blued the 6.5x55 stubbed barrel. I just made a new shim and epoxied it back in place which is my point, it's not catastrophic if a shim falls off, it's not going to while using it, most likely only when the barrel is removed which I  don't normally do during hunting season unless I absolutely have to.

Tim