Gunsmithing Chrome Bolt in AR15 = Insufficient Headspace?

[Phil3]

I was speaking with Krieger barrels and they said that if the bolt is chromed, there MAY be insufficient headspace with the barrel. The reasoning being that if the bolt is made to milspec, and then chromed, the chrome will eat some headspace.

I have a Young Mfg National Match Chrome Bolt assembly and a Krieger barrel. I would find it hard to believe that Young Mfg would sell chrome bolts that cause insufficient headspace. Still, now I have concerns. Anyone else had insufficient headspace using chromed bolt carriers?

- Phil

 

[Criver600]

Re: Chrome Bolt in AR15 = Insufficient Headspace?

Have you checked or had the headspace checked?
If you cut a minimum chamber and set the headspace with an unfinished bolt changing to a chromed bolt certainly could cause a problem. Easily corrected.

 

[Phil3]

Re: Chrome Bolt in AR15 = Insufficient Headspace?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: criver</div><div class="ubbcode-body">Have you checked or had the headspace checked?
If you cut a minimum chamber and set the headspace with an unfinished bolt changing to a chromed bolt certainly could cause a problem. Easily corrected. </div></div>

I am going to check the headspace. I'll sleep better. Krieger (the barrel maker) said the chamber they did for me was a 223 Remington chamber, cut to minimum SAAMI specs. I don't what bolt or spec they used to set headspace. They did not have my bolt. I called Young Mfg (the bolt maker). They said the chrome plating is .0002" thick, reminding me that is is NOT .002". They said that dimensional change is not enough to cause any headspace problem. I would agree, but going to check it anyway.

- Phil

 

[mark454]

Re: Chrome Bolt in AR15 = Insufficient Headspace?

I would check headspace,but i don't think you will have a problem.If it's too tight,you will have problems chambering for full bolt lockup.

FWIW,many years ago i assembled a 24" Model One varmint upper with a Youngs Mfg hard chromed bolt and it ran fine. Over 3k through it and no problems. An added benefit is the hard chrome is very easy to clean.I keep it lubed well with breakfree and the crud wipes off with a paper towel.

Another FWIW,i have a Krieger barreled varmint upper built by WOA and it is very accurate and very smooth & easy to clean.Best wishes on your project,it should be a great shooter.

 

[Downzero]

Re: Chrome Bolt in AR15 = Insufficient Headspace?

Industrial hard chrome is very thin, as Young told you.

I'd run it.

 

[11b30b4]

Re: Chrome Bolt in AR15 = Insufficient Headspace?

Should be fine to shoot. You can get a head space gage for fire no fire from brownells but I would think with the setup you listed, all will work fine. Wear eye pro and you should be good to go.

 

[jpretle]

Re: Chrome Bolt in AR15 = Insufficient Headspace?

Put it together and shoot it. It isn't a swiss watch.

 

[9H_Cracka]

Re: Chrome Bolt in AR15 = Insufficient Headspace?

"I don't what bolt or spec they used to set headspace."

Yes you do - you just typed it:

"Krieger (the barrel maker) said the chamber they did for me was a 223 Remington chamber, cut to minimum SAAMI specs."

They cut chamber headspace at .0015" to .0025" over minimum assuming a USGI spec non-chrome plated bolt. The thickness of the chrome plating on the bolt lugs is the issue. Since no-one I know of makes a bolt with lugs machined UNDER mil spec, one must assume the chrome plating is on top of the mil spec dimension bolt, hence the reason this is an issue.

Order your own or find a local smithy with a 223 GO gauge and check the headspace with your chrome plated bolt in the rifle.

 

[christian77]

Re: Chrome Bolt in AR15 = Insufficient Headspace?

I don't have a good feeling about this brother...probably ought to just sell me the BCG to play it safe