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Bolt Motion Question

This is a discussion on Bolt Motion Question within the The M14 forums, part of the M14 M1A Forum category; Originally Posted by Sailormilan2 OP, are you sure that is the point making contact with your bolt? Pretty confident it's this area. Here's another angle ...


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Old May 1st, 2020, 11:37 AM   #16
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Quote:
Originally Posted by Sailormilan2 View Post
OP, are you sure that is the point making contact with your bolt?
Pretty confident it's this area. Here's another angle where you can see the receiver has also been worn down from this contact. Following that worn ridge towards the bore is the same corner the ballpoint pen points at.
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Old May 1st, 2020, 01:11 PM   #17
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First off, it's normal to have this kind of wear on the bolt and receiver, even in a government M14. The radius that supports the rear end of the bolt is often made too large in commercial receivers which results in a lot of shuck when the bolt travels back and forth. I've seen several commercial receivers that were too much on the tight side, enough in some cases to cause binding, so it works both ways. Both cast and forged receivers are guilty of this. With use, the parts polish and wear themselves to a point where they run smoothly in most cases. I would recommend in either extreme that the manufacturer should be made aware of the problem.

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Old May 1st, 2020, 01:15 PM   #18
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First off, it's normal to have this kind of wear on the bolt and receiver, even in a government M14.

...

I would recommend in either extreme that the manufacturer should be made aware of the problem.
Thank you! I have an email in to Springfield as well, but they take a while to respond so I thought I'd ask here, too.

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Old May 1st, 2020, 01:33 PM   #19
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Pretty confident it's this area. Here's another angle where you can see the receiver has also been worn down from this contact. Following that worn ridge towards the bore is the same corner the ballpoint pen points at.

The spot your screwdriver points too is same spot in pics from #14 I showed earlier.This is your contact .This shelf runs all the way to rear of heel and does contact normaly in every M14 type rifle.

The spot you show with ballpoint pen has nothing to do with this area.Totally different machining step.

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Old May 1st, 2020, 02:22 PM   #20
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I will just throw this out there;; try a different stock;; and see what happens ??/

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Old May 1st, 2020, 04:11 PM   #21
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Pretty confident it's this area. Here's another angle where you can see the receiver has also been worn down from this contact. Following that worn ridge towards the bore is the same corner the ballpoint pen points at.
I will agree with you that the spot in your photo using the screwdriver as a pointer. That is the area causing the problem.
My earlier statement was referring to your photo using the ball point pen as a pointer.

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Old May 4th, 2020, 09:02 AM   #22
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I for got I had the cut up SAINC receiver,shows the shelf that's contacting the bolt top.
If you notice they machine a trough for the bolt leaving the extra metal inside.This creates a track for it to ride in.
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Old May 4th, 2020, 09:32 AM   #23
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So it's supposed to rub, then? I guess I'm getting it rebarreled by tonyben soon, I can show him and see what he thinks... I might be over-analyzing.

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Old May 4th, 2020, 10:13 AM   #24
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Every bolt even in USGI can rub contact there ,with the track that SA machines it might be possible to contact more so.

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Old May 4th, 2020, 03:21 PM   #25
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Every bolt even in USGI can rub contact there ,with the track that SA machines it might be possible to contact more so.
I went down the street to the local gun shop and fondled a new M1A on the rack. Significantly less contact/resistance on that one...

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Old May 4th, 2020, 05:58 PM   #26
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I don't think there is a problem myself ,receiver looks clean .I'm sure if there is a stock fitment or some burring Tony will solve that for you pretty easy.

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Old May 6th, 2020, 05:28 AM   #27
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Of course the bolt contacts the receiver as it moves to and fro. However, after the hammer has been cocked, subsequent cycling of the oprod and bolt should not feel like you are cocking the hammer again. You might not be crazy.
I have made this comment previously, but it didn't gain much traction or concurrence: the trigger group might be seated too deep into the stock. The bolt cocks the hammer, but the hammer can obstruct the bolt if it is seated too high.
How is the locking force of the trigger guard? The trigger group can pivot slightly around the spot in the receiver where the trigger guard locks into the receiver. (Remove the receiver from the stock and install the trigger group. Then you can observe the movement of the trigger group around the locking point in the receiver.) Let the hammer fall and cycle the bolt. After the hammer is cocked, you should feel just the resistance of the operating spring and very low resistance of the bolt moving between the hammer and receiver.
My solution? Shim the rear of the trigger housing with several small pieces of copy paper or brass shim stock. If the trigger guard becomes too hard to lock, you might need to clearance the from pads of the trigger guard. After you get it working right, bed the trigger housing with epoxy.

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Old May 6th, 2020, 06:43 AM   #28
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Check behind the stripper clip bridge on the upper inside of the receiver. Built a rifle using an Armscopr receiver years ago and it did not have enough clearance machined for the raised curved surface on the rear of the bolt to let it retract. Easily corrected by some careful grinding with a Dremel tool.

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Old May 6th, 2020, 12:50 PM   #29
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Quote:
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How is the locking force of the trigger guard?
Pretty tight. No wiggling once it's locked up.

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My solution? Shim the rear of the trigger housing with several small pieces of copy paper or brass shim stock. If the trigger guard becomes too hard to lock, you might need to clearance the from pads of the trigger guard. After you get it working right, bed the trigger housing with epoxy.
Got as far as shimming with the thickness of an old cut up credit card - made a little bit of a difference but not nearly enough.

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Check behind the stripper clip bridge on the upper inside of the receiver. Built a rifle using an Armscopr receiver years ago and it did not have enough clearance machined for the raised curved surface on the rear of the bolt to let it retract. Easily corrected by some careful grinding with a Dremel tool.
This was the first solution I wanted to jump to, but I'm nervous about grinding down parts on the receiver since it can't be un-ground once I've done it. Was looking for more of a 'go-ahead' from some of the experienced folks here before I broke out the Dremel...

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Old May 6th, 2020, 02:23 PM   #30
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The receiver is a 400k series SAI. It's machining is considerably smoother than previous generations of receivers. I looked at the area inside the receiver and it's quite smooth, but I will note here (didn't have time to comment on it last night) that the rifle was quite dry which may have resulted in parts that look like they were more worn than they should be.

We were crunched for time and I knocked out the barrel swap in about 2.5 hours. The rifle function checked great and I didn't see anything that concerns me.

I've had rifles that peened the hammer and bolt and his had similar peening. I wouldn't worry about it. It was a solid rifle when it left.

I need to have him come over later so I can show him how to properly lube it. But for now, there's the video on my YouTube page.

Tony.

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