Lock bolster to barrel fit

[Tim]

I am fine tuning the bolster to barrel fit on my Kibler SMR kit and need some advice.
Do I use Prussian blue to check the fit and then take down the high spots until there is
Full contact between the two surfaces? The current fit is not good and I don’t want to file off too much to where the gap can’t be closed. Thanks.

Tim

[J. Talbert]

I'm not familiar with how well the lock typically fits initially on a Kibler kit, but in general there are numerous contact points in the lock inlet which could potentially obstruct a solid fit between the barrel and the bolster.  I would guess that the metal surfaces themselves would be flat and true to begin with.
So I'm wondering, are you referring to removing wood inside the inlet, or filing metal from the barrel or the bolster?
You definitely want a good fit between the barrel and the bolster.  The trick is to determining where to remove the wood to close that gap. 

Pictures would certainly help.

Jeff

[Tim]

It’s the fit of the bolster to the barrel that I’m referring to.
I have checked the wood in the inlet and nothing needs to be removed there.
I will post some pictures tomorrow that show the how the bolster is fitting to the barrel.

[Dave Marsh]

I would contact Jim Kibler with questions.  He is always more then helpful.  Good luck.

Dave

[J. Talbert]

Dave makes a good point.  Jim is always more than happy to assist and he is surely the best able to ascertain what may be the problem.

Jeff

[Bob McBride]

There is about a 36th radius left on the inside corner of the inlet from Jim’s CNC process. I seem to remember all it took to mate the bolster to the barrel fully was scraping that radius square with a sharp 1/8” chisel. You could use an exact-o knife with a snapped off tip as well. Go slow. There shouldn’t be any inletting left to do there but you can check the bolster area of the stock with transfer color for any tiny high spot to close the gap at the bolster. I think he has a video of the fitting on his YouTube.

Also, ‘full contact’ (between the lock plate and inlet) isn’t what your looking for, if that’s what you meant. You’ll chase the lock plate all the way though the stock trying to get that. Using transfer fluid, if necessary, to find a few tiny high spots on the top half of the lock should settle it in.

[Ky-Flinter]

It’s the fit of the bolster to the barrel that I’m referring to.
I have checked the wood in the inlet and nothing needs to be removed there.
I will post some pictures tomorrow that show the how the bolster is fitting to the barrel.

If the side of the barrel is flat, and the bolster of the lock is flat, and the 2 surfaces are parallel, it has to be wood that is keeping them apart.  What else is there?

Bob's first paragraph above is on the money, but I disagree with the comment that "full contact isn’t what your looking for".  The lock to barrel fit should be tight with no gaps, lest priming powder sift thru into the lock mortise.

-Ron

[smallpatch]

Full contact is EXACTLY what you're looking for.  The only thing that can keep,that from happening is the wood in the lock inlet. Use some soot or inlet black, and see what's in the way.

[Bob McBride]

It’s the fit of the bolster to the barrel that I’m referring to.
I have checked the wood in the inlet and nothing needs to be removed there.
I will post some pictures tomorrow that show the how the bolster is fitting to the barrel.

If the side of the barrel is flat, and the bolster of the lock is flat, and the 2 surfaces are parallel, it has to be wood that is keeping them apart.  What else is there?

Bob's first paragraph above is on the money, but I disagree with the comment that "full contact isn’t what your looking for".  The lock to barrel fit should be tight with no gaps, lest priming powder sift thru into the lock mortise.

-Ron

He mentioned taking down the high spots until full contact is achieved. I initially read that as between the lock plate and wood flat in the inlet. Of course full contact of the bolster and barrel flat should be achieved. I guess being full of ham, green beans, and mashed potatoes had me a bit wobbly.

[Marcruger]

I'd want full contact.  You do not want priming powder getting down between the lock and barrel and setting up an explosive situation.  God Bless,  Marc

[Jim Kibler]

Tim,

Give me a call if your still having trouble.  There might be a little wood somewhere that is holding things up.  Make sure you've installed your lock bolts prior to checking the bolster to barrel fit.  The will tend to pull the lock inward.  Also, it's a good idea to check the fit with thin feeler stock or even a piece of paper.  The barrel and bolster should be perfectly flat so I wouldn't expect any metal needing removal.

All the best,
Jim

[Tim]

Tim,

Give me a call if your still having trouble.  There might be a little wood somewhere that is holding things up.  Make sure you've installed your lock bolts prior to checking the bolster to barrel fit.  The will tend to pull the lock inward.  Also, it's a good idea to check the fit with thin feeler stock or even a piece of paper.  The barrel and bolster should be perfectly flat so I wouldn't expect any metal needing removal.

All the best,
Jim

Hello Jim

When I get home from work I will check the fit again
And get back with you. I am the guy who returned
The barrel and You fixed the broken tang for me last week.
I did some more polishing
On the barrel this weekend to get it ready for bluing.
Thanks for replying to my message.

Tim

[Tim]

Tim,

Give me a call if your still having trouble.  There might be a little wood somewhere that is holding things up.  Make sure you've installed your lock bolts prior to checking the bolster to barrel fit.  The will tend to pull the lock inward.  Also, it's a good idea to check the fit with thin feeler stock or even a piece of paper.  The barrel and bolster should be perfectly flat so I wouldn't expect any metal needing removal.

All the best,
Jim

Jim,

This picture shows the points of contact I have in the inlet and at the bolster location.
I took off a good bit of wood in the area where the tumbler is located and still have high spots when I tighten up the lock screw. I am afraid to keep taking out wood thinking I will take the lock down too deep in the inlet. Thanks for the help.

Tim

[FALout]

The lock plate needs to be square to the barrel.  If you have the lock tipped downward, that will give you the appearance of a gap at the bolster.  Yes it’s hard to put a square on that area, but you do not have to get contact to be able to visually see a difference. This is one of those cases where working on a blank is easier, if the top, bottom and sides are square to each other, you can easily detect this.  If your basing your plate depth to a surface that is not square to the barrel to begin with, you will have problems.  Take all the parts off the lock plate, get that the way you want it mounted first, then start adding parts and checking fit with each piece.  If things get out of whack, then you know THAT item that was just put on is the issue.  Keep doing that till all is together.  I usually get the plate in first, then drill/tap for lock bolts.  It’s only then that I start putting in the guts of the lock.  I haven’t worked on one of Jim’s kits, but the barrel looks clean and straight, and doubt that the bolster was machined poorly, but each can be checked with a good straight edge up to a light.

[scottmc]

I second Falout's suggestion.  Plate first and then piece by piece. I do this even with L&R replacement locks that I put in for friends.  Takes a little longer but ensures a good fit for everything.  Based on what I'm seeing in your mortise for hits in various spots, I'm guessing your plate is probably good but a part or two is keeping you out.

[Jim Kibler]

Tim,

Thanks for the pictures.  Good news is that you're almost there.  I'm not sure what to make of the process you've had to go through.  Usually little to no wood is required to be removed on the depth.  There's always exceptions though...   So it seems you're getting good contact along the barrel and your plate has contact as well, so all you need to do is scrape out areas where moving parts are touching (sear, tumbler, sear spring etc.)

A note is that this kit is slightly older and used a Chambers lock.  Though the plate to bolster thickness was controlled decently by the assembler, there are some variations.  Perhaps this is one where the bolster thickness was on the low side.

None of this fitting should be required with our new locks. 

If you have any additional questions, just let us know.

All the best!
Jim

[Tim]

When the inlet work is done do I need to take the lock panel
Down a little to where it doesn’t look like the lock is so sunk into
the inlet? I’ll be glad to finally get finished as I am dying to shoot
This rifle.
A big thanks to all for the help.

[Tim]

With everyone’s help I was able to work on the fit of the lock
And get it fitting like it should. A big thanks to everyone
And especially Jim Kibler for answering all of my questions
And being patient with me.

Tim

[Jim Kibler]

As mentioned before, I was confused why this had to go deeper than my initial inlet.  Turns out this was a replacement lock Chambers sent Tim.  Assemblers have changed since we used the Chambers product and the bolster thickness has apparently changed as well. 

Looks great Tim!

All the best,
Jim