Gunsmithing Crooked Barrel??

[justinh]

I'm trying to put together my first rifle build here and I'm having some trouble getting the barrel to sit right. I thought you guys might be able to lead me in the right direction as to how to figure out exactly whats going wrong. Hopefully I can explain this sufficently. I'll try to attach a couple pictures.

What I have is a Defiance Deviant barreled action and a Masterpiece Arms BA chassis.

When I torque the action bolts, the barrel cants to the left enough that it just contacts one of the ribs on the chassis. I can't get it to sit concentric in the barrel channel no matter what I do. Hand tight is enough to make this happen.

I machined a fixture thats the same size as a Remington 700 with a barrel on it and this sits perfect. Because of this, I don't think the error is in the chassis.

All that's left I can think of is that either the Deviant action has a machining error or the barrel was threaded crooked. My hunch would be that it's unlikely that the action has an error in it. But, I'm not sure how to tell, or what to do next. Or is this not enough to worry about?

I could machine off the rib where it touches on the chassis to make clearance, but this seems like I'm modifying something thats not wrong in order to accommodate something with an error.

Trying to attach a few pictures that try to show how far off the barrel is in the channel and the fixture I turned sitting true.

 

[Kadams1563]

Maybe put the barreled action in so we can see that instead of the cannon barrel you made.

 

[justinh]

The last 2 pics are of the barreled action showing it off center. I just showed that other thing to explain my reasoning for saying the chassis wasn't at fault.

 

[G17C]

There is stress on the receiver due to the receiver not fitting the chassis correctly. This could be an issue with the receiver, the chassis or a combination of both.

You may want to start by looking for an obvious stress point that is causing the barreled action to shift when it is torqued down. Look for rub marks on the receiver, the recoil lug and on the chassis bedding surface. Also, torque one screw at a time to observe the shift - this may provide a clue about the stress point.

 

[Supersubes]

I seem to recall a similar thread to this one a while back. Thats pretty crooked! Is the barrel shouldering directly to the action, or is this a prefit with a nut? Who's blank is it?

I personally wouldnt alter the chassis. If the barrel is that crooked, its gonna eat up all your windage to zero, so id start there. Only question remaining is why is it that crooked? Did you do the barrel install on the action?

 

[diverdon]

Do you have or could you borrow another chassis (or BA) to try?

Have you made sure both mating surfaces are clean and free from debris?

 

[DAVETOOLEY]

Check clearance around the trigger. Something is touching somewhere.

 

[G17C]

Check clearance around the trigger. Something is touching somewhere.

Good point! My Badger M5 bottom metal needed a little fitting to accept a Timney 510.

 

[justinh]

I seem to recall a similar thread to this one a while back. Thats pretty crooked! Is the barrel shouldering directly to the action, or is this a prefit with a nut? Who's blank is it?

I personally wouldnt alter the chassis. If the barrel is that crooked, its gonna eat up all your windage to zero, so id start there. Only question remaining is why is it that crooked? Did you do the barrel install on the action?

It's shouldered directly to the action, its a bartlein blank. I did not do the barrel install, I bought it as a barreled action.

 

[justinh]

There is stress on the receiver due to the receiver not fitting the chassis correctly. This could be an issue with the receiver, the chassis or a combination of both.

You may want to start by looking for an obvious stress point that is causing the barreled action to shift when it is torqued down. Look for rub marks on the receiver, the recoil lug and on the chassis bedding surface. Also, torque one screw at a time to observe the shift - this may provide a clue about the stress point.

I guess by torque down I should say that just holding it flat in the vchannel will show it being off. No torque at all, just finger tight or even holding it down flat by hand will show it crooked. It's only because the barrel's heavy that you even need to push on it at all

 

[justinh]

Check clearance around the trigger. Something is touching somewhere.

Someone else suggested that, I took the trigger off right now and I'm trying to fit it without. Didn't make any difference.

 

[LRI]

Pull the trigger off the action and assemble receiver/barrel only.

If the issue repeats, then it's likely the barrel.

If you have machined mandrels, then I'm assuming you did your own barrel work too. If that is indeed the case, just set the shoulder back around .013-.014 to index the "cant" to a vertical plane. Then you won't even notice it. Of course it'll have to be headspaced again, but not a big deal.

This isn't all that uncommon. Barrel contours can cause a barrel to wander. It has no negative impact on paper punching down range.

One last check:

Throw the chassis in a vice, indicate where the receiver registers parallel to the X axis on the machine. Now set your receiver in there. Run an indicator off the side of the rail. It should be darn near perfect parallelism. Now run it off the face of the action. It should be square/parallel to the Y axis.

One or two .001's aren't enough to get riled up over. One last way to check is to feeler gauge the gap on either side of the barrel up front. Say .03 on one side and .07 on the other. .04" right? So split that and add it to the low side, .02+.03='s .05.

Now measure from face of action to that point. Say it's 11.0 So, .02/11='s .0018" deviation per inch. If you see anything close to this off the sides/face then you have your problem narrowed.

As the math reveals, it doesn't take much for the ol eyeball to notice it.

C.

 

[justinh]

Pull the trigger off the action and assemble receiver/barrel only.

If the issue repeats, then it's likely the barrel.

If you have machined mandrels, then I'm assuming you did your own barrel work too. If that is indeed the case, just set the shoulder back around .013-.014 to index the "cant" to a vertical plane. Then you won't even notice it. Of course it'll have to be headspaced again, but not a big deal.

This isn't all that uncommon. Barrel contours can cause a barrel to wander. It has no negative impact on paper punching down range.

One last check:

Throw the chassis in a vice, indicate where the receiver registers parallel to the X axis on the machine. Now set your receiver in there. Run an indicator off the side of the rail. It should be darn near perfect parallelism. Now run it off the face of the action. It should be square/parallel to the Y axis.

One or two .001's aren't enough to get riled up over. One last way to check is to feeler gauge the gap on either side of the barrel up front. Say .03 on one side and .07 on the other. .04" right? So split that and add it to the low side, .02+.03='s .05.

Now measure from face of action to that point. Say it's 11.0 So, .02/11='s .0018" deviation per inch. If you see anything close to this off the sides/face then you have your problem narrowed.

As the math reveals, it doesn't take much for the ol eyeball to notice it.

C.

The trigger is off right now. I've been trying without.

I did not do the barrel work, I bought the action and barrel together so I wouldn't have to screw with something like this... If i refaced the shoulder to get it square again, would there be enough play in the threads to take that up without having to chase the threads or anything? I have machine tools, but I don't have gunsmith tooling. I'd have to buy a chamber reamer etc.

Thats a good idea, I could put the thing in a mill and run down the center and measure how far off center the muzzle is. Don't know why I didn't think of that!

 

[DAVETOOLEY]

Chad Brought up a good point. If the barrel was chambered using rods to align the first few inches of the bore, the muzzle is left to run wild. If the barrel wasn't "clocked" to the 12 o'clock position that could well be your problem compounded by the diameter. The fix is to start over with a new chamber, because there is no way to set the barrel up the same way to clock it. Any fix would cause perpendicularity issues between the barrel threads and shoulder. Or you could reduce the diameter of the barrel and shoot it. The target tells all.

 

[BurnOut]

Something else to look at before investing in additional parts or machine work may be the interface between the chassis and the tang of the action. I battled a Savage/B&C stock combination trying to get the barrel centered in the barrel channel for quite some time, and it was only when I relieved/bedded the tang area that I was able to get everything properly sorted out.

 

[justinh]

Well, I did as suggested and put the action up in a mill and found the centers. the center of the muzzle is off .0827 compared to the center of the action. Is there any way to even fix that? I emailed the smith that put the barrel on, waiting to hear back.

 

[scudzuki]

Check clearance around the trigger. Something is touching somewhere.

My thought too.
Remove the trigger and see if it drops in centered.

 

[z28kid]

Well, I did as suggested and put the action up in a mill and found the centers. the center of the muzzle is off .0827 compared to the center of the action. Is there any way to even fix that? I emailed the smith that put the barrel on, waiting to hear back.

That's quite a bit. Hopefully your Smith will get it worked out for you quickly.