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  #1  
Old 04-30-2012, 10:16 AM
chief jeff chief jeff is offline
 
Join Date: Oct 2011
Location: Bixby Oklahoma
Posts: 13
Default G I bolt conversion

Hi all I am thinking of having a GI bolt fitted to my polyteck M14. Cost $150.00 to have done, already have Winchester bolt. Is this something you would recomend I do.
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Old 04-30-2012, 10:53 AM
MP10-32 MP10-32 is offline
 
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What are they doing for $150??? You are supplying the bolt, correct? If they are just putting in your bolt and checking for correct headspace--that price seems a little steep to me.

A Ploytec maybe on the large size and might require setting the barrel back and finish ream. I would want to know what is all included in the $150 price?
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Old 04-30-2012, 11:49 AM
d7cook d7cook is offline
 
Join Date: Mar 2011
Location: Ohio
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Quote:
Originally Posted by chief jeff View Post
Hi all I am thinking of having a GI bolt fitted to my polyteck M14. Cost $150.00 to have done, already have Winchester bolt. Is this something you would recomend I do.
If I remember correctly the Chinese bolts have a tendency to be soft and replacing it with a GI bolt is a good idea. There is a dimension issue on the Chinese receivers that require fixing before they will accept a GI bolt. That's why it's $150.
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Old 04-30-2012, 02:48 PM
Scott in Michigan Scott in Michigan is offline
 
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Location: God's Country
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Quote:
Originally Posted by d7cook View Post
If I remember correctly the Chinese bolts have a tendency to be soft and replacing it with a GI bolt is a good idea. There is a dimension issue on the Chinese receivers that require fixing before they will accept a GI bolt. That's why it's $150.
They may or may not be soft. The only way to find out is to either to buy headspace guages or have it checked regularly. Mine has 2300+ rounds through it and the headspace has increased by only .001", an amount I would consider normal finish wear only.

Unfortunately, there is no way to predict which ones are soft.
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Old 04-30-2012, 03:08 PM
M14 M14 is offline
 
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Location: south mississippi
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Quote:
Originally Posted by Scott in Michigan View Post
They may or may not be soft. The only way to find out is to either to buy headspace guages or have it checked regularly. Mine has 2300+ rounds through it and the headspace has increased by only .001", an amount I would consider normal finish wear only.

Unfortunately, there is no way to predict which ones are soft.
Good advice above in this quote. You can buy a go and no go gauge, and check your headspace for about $27.00 each. Keep an eye on it every couple hundred rounds before replacing with a G.I. bolt. Lots of foreign bolts are fine.

Also check for lug contact on both sides first, by using a black magic marker on the back of your bolt lugs and then working it in and out of battery by hand with op rod removed and putting pressure to the rear so the lugs rub tightly against receiver lugs. Remove bolt and look for good contact at both sides. If the left side is not touching or has very little marker removed, and your headspace go gauge is tight or will not close, you can use lapping compound to lap the bolt in to proper headspace. Do not take too much material off without checking headspace again regularly.

To close the left side up to contact correctly, you will need to lap the right side, then lap both sides at once to desired headspace once the left side has decent contact. I never take more than .002 off any one side, bolt or receiver. Total - .004 You do not want to go through the surface hardening and it is usually supposed to be between .012-.018 thick on G.I., but may be considerably less on chicoms.

In my experience, the chicom receivers are very hard, much harder than the bolts. It is also my findings that most chicoms were very tight headspaced, way under S.A.A.M.I. recommended specs. I found two last week that were 1.627 when SAAMI calls for 1.630 minimum. The owners had been shooting mil-surp ammo through them. Just lucky they did not get hurt because some of the foreign mil-surp is long on case headspace.

My advice is that everyone should have their headspace checked on any high powered rifle before firing.
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  #6  
Old 04-30-2012, 05:15 PM
howardhughes howardhughes is offline
 
Join Date: Mar 2010
Location: NC
Posts: 336
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Depends on dom of rifle...jon wolfe here in nc showed me a bolt conversion they has 2 hours into as they had trouble lapping bolt /cam... engaugement was poor. I have built many m1 garands and carbines...the m14 bolt system is a bit hard to HS, I send it out. Yes the receivers are hard..and later rifles HS easy (Poly rifles).
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  #7  
Old 05-01-2012, 03:57 AM
Front Line Front Line is offline
 
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Why ruin a WRA bolt? Use a SA if you have to.
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  #8  
Old 05-01-2012, 09:02 AM
slikwilli420 slikwilli420 is offline
 
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Location: Southwest MI
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Because SA bolts are much less common than WRA for M14's
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Old 05-01-2012, 09:05 AM
Perplexed Perplexed is offline
 
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Location: Oklahoma
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Quote:
Originally Posted by slikwilli420 View Post
Because SA bolts are much less common than WRA for M14's
In terms of rarity, it's SA > TRW > WRA > HRA (least to most common) - if I'm not mistaken?
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  #10  
Old 05-01-2012, 03:05 PM
Sailormilan2 Sailormilan2 is offline
 
Join Date: Jul 2010
Location: Surrounded in Central CA
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Quote:
Originally Posted by M14 View Post
You got that right. I know Jon's pain. One of the one's above I talked about took over three hours to lap in. No breaks, no stopping other than wiping sweat off my face, and checking headspace every so often. Seriously thinking about not doing anymore of them myself. If anyone wants a G.I. bolt in them, farm it out....To Jon....haa haa.
Which bolt did you have to lap? TRW, SA, or Win? I have had to do more work fitting TRW bolts, than SA or Win. I have read that that is the norm too, since many TRW bolts were made to be replacement bolts based on estimated wear. Estimates that were incorrect. So, TRW bolts tend to be a bit longer, and therefore a bit harder to fit to Polytech receivers.
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