Problem with my bolt in my Polytech M14 not always locking up. NOW WITH PICTURES!

I bought a Polytech M14 yesterday and it was done up into a practice gun for NM. It has a NM stock sights and a TRW bolt. My issue once I cleaned it and greased it up is that with some of my reloaded M80 ball the bolt goes almost all the way shut on it's own and then you have the slap the oprod to get it the rest the way close. I full length size all my brass to the max in both my resizing die and again in the resizing die that I use with my Dillon power trimmer. So while the headspace of my rounds may be an issue (since it chambers all of the USGI dummy rounds I have) I don’t think it’s the only issue this gun has. I think that the locking surfaces on the receiver are on the tight end of the specs, which while great for NM to have very tight headspace. I came to this conclusion when I put in my minimum field service gauging bolt in even it only will go half way into battery with an empty chamber. So what I did was stone all the locking surfaces on the receiver and TRW bolt as well as the bolt face itself. I didn’t want to go too deep with removing material because I didn’t want to get down to any soft steel but I was hoping that I could make the locking surfaces smoother so that the inertia of the bolt would more efficiently allow it to close. I also did the bolt face to provide less resistance against the case head during locking. I was also hoping that by taking off a few ten thousandths off all those surfaces that it would help to open up the total headspace a little. It still has trouble going into battery with about five out of any given 20 rounds when I operate the gun manually but when I shot it today with 60 rounds I didn't notice any issues. I guess that the additional inertia of the metal parts rebounding off one another adds a little more force when the bolt closes. Any Ideas? I'm thinking that the more I shoot it it will eventually break in and the problems will go away on their own.

There's only 2 locking surfaces, as you call them.
Left & right receiver & bolt lugs.
And you stoned the bolt face too ?
Not sure why you would do all that but, sounds like somebody failed to headspace the bolt.
Did you just drop the TRW bolt in it & start shooting ??
Have you tried some white box Winchester ammo ?




I read the part in red 3 times & still don't fully understand it.




I doubt you removed "a few thousandths" unless you got carried away.
The bolt face should be left alone unless you really know what you're doing.
Hopefully you didn't bubba anything that can't be fixed correctly.
Have you considered having someone look at it, preferably someone who knows Chinese rifles ?



.

Well the bolt came with the gun. The last gentleman who owned it used it to practice shooting high power. Surprisingly even with the Chinese barrel it shoots very well. It basically clover leafed at 25y when I zeroed it.

As far as stoning goes it was something I wanted to try to see if it would help. It seemed to make little or no difference. I knew I didn’t want to get carried away with it so once I felt I wasn’t getting the results I wanted I stopped.

As far as having someone ream the chamber to deepen the headspace is concerned I'm not sure what negative effects reaming could do to a chromed chamber and bore but I'm sure it wouldn’t be good.

I haven't tried any factory ammo in the rifle yet. But I might get some USGI M80 ball to test out. I'm sure it will work fine with that ammo.

As far as the test bolt is concerned. It is a gauge that is made from a bolt machined to the minimum allowable tolerances for safe operation. And when I put it in the rifle just to get a comparison between it and the bolt that came with the gun this test bolt couldn’t even be made to go into battery more than half way. Since its machined on the bolt face and locking lugs to the minimum allowable tolerance it should have had no problem locking up. As I said before it’s as if the locking lug recesses on the receiver were not machined to the correct tolerances. I know that more research has to be done before I can make a conclusion and have some sort of idea of what to tell the gunsmith. In addition to that I know that the angle of the locking surfaces has to be maintained and that the surfaces need to be completely flat which is why I stopped stoning at a certain point because it can be next to impossible to maintain those characteristics when stoning by hand.

There is a simple solution. Send the rifle to someone familiar with M-14s and have them fit the bolt.

Marty

Obviously it needs to have the bolt replaced with a Chinese one!

Sorry, I couldn't help myself

You first want to eliminate 'you'. You state that the problem revolves around your reloads, Does that rifle also have the same issue with issue or factory commercial ammo? If not, then I'd acquire one of Wilson's case gauges and see if my stuff was in spec. I know it sounds elemental to an experienced shooter, but if you've a minimal headspace bolt along with a chamber that is very tight then what you describe is about what happens. I once had a old pre-64 M/70 in '06 that did EXACTLY as you describe..............a change in dies solved my problem.

OK so you used a test bolt like the one pictured below to check for lock up on a USGI bolt & as a headspace gauge ??
It's not a headspace gauge at all & shouldn't be used as such.
If the test bolt doesn't close all the way, you need to have a bolt conv. done properly & by someone who knows how.
Don't send it to just anyone for the work & choose your gunsmith wisely.
If you want help with it let me know, I can get you fixed up the right way.








Reverse bolt conversion ????
I couldn't help myself.




.

1. It was previously used to practice for High Power. OK, could mean all his loads were either custom formed for that chamber or he used milsurp to practice.
2. Bolt doesn't always close. STOP WHAT EVER YOU ARE DOING AND STEP AWAY FROM THE RIFLE. If it doesn't always close, it is quite probably it will also fire when not all closed. An out of battery BOOM like that can not only hurt you but the folks around you. Probably the reason behind the individual selling the rifle also.
3. You are not an M14/M1A smith. I am but I don't work on Polytechs for a number of reasons. There are a number of folks up on m14TFL who do work on them. Get one.
4. The bolt needs to be replaced. You ground on it so it is no longer a "safe" bolt.
5. The rifle needs to be headspaced. Check the barrel for wear also. Could be you could get the barrel replaced and the headspacing comes with the job.
Good luck. You showed the uncommon decency and common sense of asking the questions, so your heart and mind are in the right place.

You are a M14 smith ? but, don't work on Polytechs ?
If you were you wouldn't make such rash judgements about what the rifle needs without having looked at it 1rst.
It's not possible to offer a solution without seeing exactly what is wrong but good luck with that one.

The bolt needs replaced ?
Again, it's not possible to offer a solution without having seen it.
I don't see any pics from OP to back up your assessment.

Oh & get a perfectly good barrel replaced while you're at it ?
There's nothing wrong with Chinese barrels if no damage has been done to it.
Again, no way of knowing if it's good or bad without checking it.
Again, I don't see any pics from OP to back up your assessment.

Good luck with those other so called Chinese rifle experts.
Here's a TRW bolt that one of them ground on the lugs.
NOT the right way to do a bolt conv. but good luck with that too.
Left lug has no contact.
Right lug only has about 25% contact in the middle.






.

There is a REASON that some talented gunsmiths charge a decent chunk o change to fit U.S.g.I. bolts to Chinese M-14/S's

Sorry if you were burned by the seller, (did you SEE him shoot matches with that very rifle, or is that what he told you?)

The U.S.G.I. bolt is NOT a drop in part for the Chinese M-14/S

Actually the M14/M1 bolt is not a drop in for any rifle, at the least you need to do head-space checks and most of the time it needs to be lapped to the receiver if you want decent lug contact. This goes for any Garand or M14 type rifle.

To dogrunner

I do appreciate your input. A lot of the brass that I use in my reloads were first shot in the FAL that I had and if you are aware of what fired brass from some FAL's looks like you will know that the rim can be distorted a bit. Another thing that I know my dies don’t fully iron out (and I will have a hard time describing this with out picks) is the slight angled expansion of the case neck right at the juncture between the shoulder and the neck. If you have ever closely examined brass fired in a M249, SCAR 16 or a M240 you know what I am talking about. I do maintain my stance that the rifle has a tighter than normal chamber so that the reloads I am shooting through this gun cause problems only because of the imperfections in the cases left by my FAL that the dies I have cannot fix completely.

To WCG

This is the bolt that I used as a comparison to the bolt in the gun currently. I did not use it with the USGI headspace gage as per the TM but I was not trying to determine headspace with that bolt. I was only curious if it could show me if there were any other issues the rifle might have. I have noticed that the bolt that came in the rifle seems to have had the bolt head radiused to fit the rifle. To avoid confusion this is not work that I did to the bolt. It was that way when I got it. Even so the bolt head has still left a radial indentation on the barrel above the feed ramps. This indentation is also apparent at the top of the same part of the breech area of the barrel where ever the bolt head has come in contact with it. I am starting the think that the barrel threads might not have been machined to the proper timing therefore setting it too deeply into the receiver and therefore accounting for the relative tightness of headspace and damage to the breech face. I don’t think having the barrel swaged and having it reinstalled would fix the problem as is recommended in my 50 level M1 garand TM (I know its not an M1 but the mechanics of rehaul maintenance are similar) for solving timing issues. I may end up needing to have a new M14 barrel installed and properly headspaced to solve this issue. Then again it only appears to be an issue with my reloads.

Here are some pics

The two bolts the one on top is the one from the rifle the lower one is the test bolt



Here is a close up of the bolt heads. Notice how the left most one (the one that came in the rifle) has a radius to the head whereas the one on the right, which is the test bolt does not.



Here is a close up of the chamber. Can see the top of the barrel that the extends past the point of being flush with the receiver. In the portion above the feed ramps you can see a radial gouge that has developed from the bolt impacting the barrel.



To Ming_The_Merciless

I did not meet the original owner of this rifle. I bought it at one of my local gun shops. I do believe by the amount of money spent converting this rifle to what I believe to be NM configuration and by the testimony of the proprietor of the gun shop (who I personally trust) that this rifle was used by the previous owner as a high power practice rifle. The following pictures will hopefully show that. One thing that they do not show is the glass bedding that was done on the stock. Like I said it is an extremely accurate rifle so I do believe my gun dealer's claims.

Here is the rifle



Here is a close up of the receiver. Notice the NM style sights. The windage is also graduated in 1/4 MOA adjustments. In fact the whole sight is US made the elevation drum in marked in meters and the sight ramp is marked NM. The MFG is WCE.


Sorry for this lengthy reply. I felt some issues needed to be addressed.

small base sizing die should of been used before getting out the files. or at least non-reloaded ammo.

My rounds will freely fall all the way in and out of the chamber on thier own so I dont think it was and issue of case bulge.

Also to reiterate. I had stoned the surfaces in the rifle that I was talking about. I didnt file or sand them or anything else. The stone I was using is equivilant to about 600 or finer grit sand paper. I estimate that at most I may have removed about .0001" of material. More or less all I did was polish these surfaces.

In the future instead of stoning, try lapping the receiver lugs. Even with this you will need to check headspace after a proper lapping job as it may mess with headspace. Usually the lapping job is done before the final headspace is cut. Your stoning is a nono especially since it was done after the rifle was assembled. My guess is the previous owner may have owned more than one M14 and in a cleaning spree put the wrong bolt back into this rifle. You need to have it checked out by a M14 smith and fixed properly, please put your stones away.

Would it be possible to lap the lugs now? I didn’t think of that at first. How is it done? If I am thinking of the process correctly you place oil on the parts to be lapped and put a lapping compound on the oil and then cycle the parts until the desired effect is achieved repeating when the lapping compound is used up as necessary. As I may have said before I have not stoned so much as to change the geometry of the parts in question.

If the chamber & bore are good the barrel can be saved.




I'll say it ounce.
You need to have the bolt conversion done & done right the 1rst time.
Since you obviously don't know what you're doing why not have it done by someone who knows how ????
You were very lucky when you fired the rifle before & it didn't fire out of battery but, you may not be so lucky by saving $$$$ doing a job you know nothing about.
It only takes 1 round to ruin your day (or the rest of your life) & you won't know till it's to late.

If you screw up everything it will cost much more to correct the problems you created.
A couple guys have already given poor advice so be very carefull what you choose to do.





Hey where is that ripper51 guy ?????
He must be hiding somewhere.




.

Again, I suggest a good M14 smith as you seem to fail to realize how dangerous the dimensions and tolerances you are messing with.

Since it's apparent that I need help on this who can do the work reliably? I'm looking for a company that services M14's and M1A's. I would prefer to have a web site I can look at then just a phone number to a guy accross the country.

Send it to Warbird's custom guns, he is one of the best in the country when it comes to Chinese M-14's.

http://www.warbirdscustomguns.com/

+1

+2

+3

You know, Warbird, the guy who's been giving you good advice all along on this thread...

Fulton Armory and SEI are other possibilities, but Warbird would be at the top of my list.

+4 on Warbird. Does a great job, does it right, great price and short turn around time.

Where did you get the TRW test bolt? Is it for sale?

+5 on Warbirds and we could probably get into + thousands on Warbirds the man knows these rifles and will straighten yours out.

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