Gunsmithing Barrel Tennon Theads - Boogered From Base Screw...

[Wheres-Waldo]

I found this while tearing down my rifle in prep. for coating.

The base screws were never torqued passed 20 inch-lbs.
Im in fear that when I take the barrel off, Im gaurentee'd to mangle the threads inside the action...not a good deal...

Is there anything I can do for this?
Aslo...Im confused as to why this even happened to begin with?
All my base screws are the same length...
The only thing i can think of is that a custom made 45MOA base is so much slimmer in the front that it allowed the base screw to do this.

 

[SDWhirlwind]

Re: Barrel Tennon Theads - Boogered From Base Screw...

Pretty hard to see from your pic but thread looks to be mashed considerably. If as bad as it looks in real I can't believe that that couldn't have been easily felt when tightening the screw???

Other than going in with a minor diameter end mill and removing as much of thread as possible I don't know how you unscrew without some galling????? However, I am sure the real smiths with experience might have an answer. Some of dem turds are pretty handy!!!!

 

[Wheres-Waldo]

Re: Barrel Tennon Theads - Boogered From Base Screw...

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: SDWhirlwind</div><div class="ubbcode-body"> If as bad as it looks in real I can't believe that that couldn't have been easily felt when tightening the screw???</div></div>
My torque wrench does not have a <span style="font-weight: bold">Hey you're encountering tennon threads! </span> setting...

Usualy when things get tight - they resist the action of turning.
Usualy when things encounter delicate barrel threads - they also resist the action of turning.

Either way, this barrel has been on and off a few times...I know this occured recently.... here is a few more pictures of hopefully better clarity.

 

[yote_slayer31]

Re: Barrel Tennon Theads - Boogered From Base Screw...

That looks bad. Maybe try a needle file and lots of patience

 

[Wheres-Waldo]

Re: Barrel Tennon Theads - Boogered From Base Screw...

Pending what one of the many smiths on here say, Ide really like to send it off. There's adjacent threads in a very small work-space here... deffinately something for a qualified gundoctor to get into.

 

[SDWhirlwind]

Re: Barrel Tennon Theads - Boogered From Base Screw...

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Wheres-Waldo</div><div class="ubbcode-body">
My torque wrench does not have a <span style="font-weight: bold">Hey you're encountering tennon threads! </span> setting...

</div></div>

Well excuse me for my comments/suggestions, guess telling the difference between a few inch pounds and a 100ft. lbs. is harder than I imagined! I never cease to amaze myself as to my stupidity in trying to help people with their problems on this forum!!! I'll go away!

 

[wnroscoe]

Re: Barrel Tennon Theads - Boogered From Base Screw...

Do not try to remove the receiver as is.

As I see it, you have two choices.

1. Coat rifle as is and worry about the thread issue at the next barrel install.

2. Have the crest of the damaged barrel thread milled off to at least the datum line of the thread so the receiver can be removed with minimal to zero internal thread damage.

#2 is a simple step as long as a mill is involved.

 

[Wheres-Waldo]

Re: Barrel Tennon Theads - Boogered From Base Screw...

SD, I meant no harm in my comments...just that 20 inch-lbs is 20 inch-lbs, weather its torquing down a screw, or crushing barrel threads in the process. Reguardless, I meant no harm

Roscoe...I use this little guy as a switch barrel rifle, and have more than one barrel for it. If any damage occured to the reciever threads, Ide be out a reciever and a few barrels...

I can live with threads being milled down...
I am worried that the damaged threads may have sprawled out to the point that they cant be 100% milled clean...but I cant tell by looking at it....

On the shelf she goes until the rest of me parts come in for some pre-existing misc. gunsmith work.

 

[wnroscoe]

Re: Barrel Tennon Theads - Boogered From Base Screw...

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Wheres-Waldo</div><div class="ubbcode-body">I use this little guy as a switch barrel rifle, and have more than one barrel for it. If any damage occurred to the receiver threads, I'd be out a receiver and a few barrels...

I can live with threads being milled down...
I am worried that the damaged threads may have sprawled out to the point that they cant be 100% milled clean...but I cant tell by looking at it....

On the shelf she goes until the rest of me parts come in for some pre-existing misc. gunsmith work. </div></div>

That dictates milling the thread down. I doubt the scope base screw damaged the barrel thread past the datum line. My only concern is where the damage is next to the scope base hole.

Even if all the damage cant be milled off/down, what's left at that point will be minimal at best. With a generous amount of Kroil and a little care, the barrel should come off with minimal effort.

 

[LRI]

Re: Barrel Tennon Theads - Boogered From Base Screw...

Easy fix.

C.

 

[customshooter]

Re: Barrel Tennon Theads - Boogered From Base Screw...

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Wheres-Waldo</div><div class="ubbcode-body">Pending what one of the many smiths on here say, Ide really like to send it off. There's adjacent threads in a very small work-space here... deffinately something for a qualified gundoctor to get into. </div></div>

as long as you have a steel action, you should be fine. the actins are typically treated to over 30 rc...waaaay harder than the barrel that wont even register... clean up with a single point is also a breeze in the worst case//

 

[jasonixo]

Re: Barrel Tennon Theads - Boogered From Base Screw...

A 9/64 flat end mill will remove the damaged thread cleanly.

 

[TCA4570]

Re: Barrel Tennon Theads - Boogered From Base Screw...

Do you have access to a mill?
If so, there is no reason to send it off.
Takes longer to explain than do.
We do a lot of PITA jobs, this is easy!
If you want to do it yourself mail or pm me and I'll write you up detailed instructions.

I've cut out smaller taps, deeper than that with a mill.
Fixing that is easy.
You'll be switching again in no time.

TC

 

[Jim See]

Re: Barrel Tennon Theads - Boogered From Base Screw...

99% of the newbies out there could learn a lesson from this, so pay attention to what I am telling you.

ALWAYS when mounting a scope base to a reciever, set the rail on the reciever, pick the shortest supplied screw with the base if their is one, gently screw in the front most base hole/screw, as soon as you feel any resistance STOP, now with only that screw in the reciever, wiggle the scope base, if there is lots of slop there, your screw is bottomed out on the thread tennon. STOP back out the screw and grnd it shorter. Repeat the process until the screw is short enough to not bottom out.

This is a very simple way to not screw up your rifle, and the reason I prefer to mount bases and rings on all the rifles that go out of my shop.

 

[TCA4570]

Re: Barrel Tennon Theads - Boogered From Base Screw...

Jim is right.

Words from a famous lawyer.

"If it doesn't fit you must a quit." (kinda)

TC

 

[Wheres-Waldo]

Re: Barrel Tennon Theads - Boogered From Base Screw...

Thanks for all the comments guys, it was a stupid mistake...

None the less, it did happen and Ide like to put it in the hands of someone capable. Mr.Dixon will be recieving some reamers and die blanks to cook me up some dies for this barrel; so Im just going to send it his way along with everything else.

 

[SScott]

Re: Barrel Tennon Theads - Boogered From Base Screw...

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Jim See</div><div class="ubbcode-body">99% of the newbies out there could learn a lesson from this, so pay attention to what I am telling you.

ALWAYS when mounting a scope base to a reciever, set the rail on the reciever, pick the shortest supplied screw with the base if their is one, gently screw in the front most base hole/screw, as soon as you feel any resistance STOP, now with only that screw in the reciever, wiggle the scope base, if there is lots of slop there, your screw is bottomed out on the thread tennon. STOP back out the screw and grnd it shorter. Repeat the process until the screw is short enough to not bottom out.

This is a very simple way to not screw up your rifle, and the reason I prefer to mount bases and rings on all the rifles that go out of my shop. </div></div>
Thanks for sharing guys, some of this stuff sounds like common sense, but most of us really don't think things through until it is too late.
SScott

 

[18Echo]

Re: Barrel Tennon Theads - Boogered From Base Screw...

It may be "common sense" but I had a VERY well known gunsmith with several record guns he built under his belt along with several shooting records he shot, build me a 7mag where the the bolt wouldn't rotate closed. I took it to another shop that was closer than driving to where he was, and come to find out the front base screw was so far down in the receiver that a bolt lug was hitting it and not letting it fully rotate. Then the smith said I wasn't getting more than 50% contact on one of the lugs and the bolt face was buggered. And to add insult to injury it took a year to complete just that....

The "world renowned" gunsmith charged me 1500 for blueprint, barrel install, and install of a badger FTE (which he also buggered because it didn't time right). The other guy charged me 350 for doing a full blue print, new barrel install, and fixing the scope base screw. lesson learned by me....