I’m wondering if I can re-use a Colt bolt in a new barrel after 1500-2000 rds of use (probably an over-estimate). Or should I get a new bolt? I’d get the headspace checked either way. I know this isn’t the first thread about this, but I’m curious about the specific round count.
Yes, you certainly can.
The lifespan of a bolt cant be quantified exactly, if you want a number 5,000 rounds is as good as any. Things such as gas system, firing tempo, etc. all impact longevity.
You will probably need to replace the extractor/extractor spring before you need to replace the bolt itself. So I’d put together a bolt repair kit: gas rings, extractor, extractor spring and insert, extractor extractor pin, ejector roll pin, ejector spring and ejector. You can buy them already put together in kit form from online vendors.
Inspect the bolt for cracks when you clean - around the cam pin hole, and, of course the lugs, and face of the bolt.
Folks report that most often the lugs adjacent to the extractor of first to go, but my experience is I’ve never broken one, yet. I’ve seen more break at the cam pin hole, than I have at the lugs, probably because the rifle stops working when the bolt breaks in half, and you may be able to keep shooting with a chipped or broken lug, depending on where the pieces end up.
Just to be safe, make sure you have someone check it with a field gage, otherwise your GTG.
double post
Thanks for the thorough response! Would a Go/No Go gauge be ok? I think I remember a field gauge being something different.
IIRC, a go and a no-go are actually 2 different gauges. I remember the USMC and the US Army had different specs for checking headspace, but I can’t recall the specifics. Either way, I think a field gauge is the “biggest allowed” headspacing.
https://www.brownells.com/gunsmith-tools-supplies/measuring-tools/headspace-gauges/go-no-go-gauge-sets-prod26876.aspx
https://www.brownells.com/gunsmith-tools-supplies/measuring-tools/headspace-gauges/5-56mm-maximum-headspace-gauge-prod6646.aspx
Thanks. That all sounds right. I did a little research after I realized I had no idea what the difference is. Seems like people use the field gauge more if used parts are involved.
The military uses a Field Gage that is 5.56. If you use a .223 gage, you will get a false reading. Your round count isn’t very high and all things being equal, it should be fine. Considering how cheap bolts and other components are now, I would get a spare anyways.
Thanks. I’ll locate or buy 5.56 field gauge. I’m well aware of the chamber difference. The Colt bolt looks good, but I’ll give it a more thorough inspection before using it with the new barrel. I probably will get a spare bolt sometime soon, but I’ve already spent a lot on gun parts this month. Then again, a new bolt isn’t much more than a field gauge.
This… Iraqgunz gave me a bad ass mil gauge. However I wouldn’t say the average guy needs one. 2k rounds isn’t much, and I wouldn’t even bother checking it.
Sweet, thanks. Pending thorough inspection, I’m gonna re-use my bolt. I found a local gunsmith with a field gauge and a no go gauge. I’ll have him check just for peace of mind.
If he’s got gauges that require the ejector to be removed, I’d just pass. Unless he’s a whiz bang AR armorer… I’d pass some dude punching out pins on my gun. Just my 2 cents.
Thanks for the heads up. Didn’t know disassembly may be required. I may pass on that.
I wouldn’t even bother with a headspace gauge unless you are putting a Bear Creek barrel on it or some similar trash.
Won’t be using a low end barrel. Very likely will be a DD barrel.
You can go between 5,000-10,000 rounds (on average) on a properly head-spaced bolt before you need to be concerned with checking for cracked locking lugs.
Here’s an Army Enginerd study on bolts and locking lug crack propagation:
https://pdfs.semanticscholar.org/566b/1271350753d0655493ae05820f84258e20ed.pdf
Pulling the bolt apart is necessary with more common gauges, the Mil version is rebated so that this isn’t necessary.
Thanks guys. The Colt bolt looks just like it did when it was new. Compared it to the bolt my new DD upper. On a side note, the extractor lug on the new DD bolt looks a little worn around the edges. Doesn’t look like brass staining. The picture isn’t great, but just something to keep an eye on?
If you’re talking about the little lug on the center of the extractor, don’t worry about it. It actually doesn’t do anything for lockup.