Using a diff Bolt Carrier and Bolt?

payj · #1 09-14-10, 14:56

Hey,

I have a ym nm bcg and bought for the hell of it an ion-bond bolt from denny's guns. Before I shoot it, I just wanted to know if it is ok to swap them out like that?

thx

rychencop · #2 09-14-10, 15:00

it's fine. you don't want to use a bolt from one rifle in another though.

Iraqgunz · #3 09-14-10, 15:04

Generally speaking (as we have discussed before) you shouldn't swap bolts between different weapons. If you need to do it, then you should do the proper headspace check.

The real issue would arise if you have a barrel that had xxxx thousand rounds through it and then you replaced the bolt. I recommend that always check the headspace whenever you can.

Jimbo45 · #4 09-14-10, 20:20

I have heard for so many years, to not swap bolts between guns, starting in the Army. I do keep my bolts in the guns that they came in, or I build them with, for really no other reason, than there being no need to swap them around, and this old advice from way back.

Using quality, in spec parts, I have never checked the headspace on anything I have put together or purchased, and have had no issues. Now if I had proper headspace gauges on hand, I probably would take the time to check, but I have never had the need, I guess.

But, has anyone, ever, heard of, seen, or personally experienced a problem, when swapping quality bolts or bcg's between uppers? I haven't. I could see that sticking a bolt with 40,000 rounds on it, in a barrel with a very long and loose chamber to begin with, might be an isssue. But, chances are, that barrel had a bolt in it, with as much wear anyway.

I don't understand the reasons for recommending to never put a new bolt in a xxxx round barrel. Maybe I am missing something, can someone explain the reasoning here?

Iraqgunz · #5 09-15-10, 18:28

The reason is simple. Excess headspace is a bad thing. Generally you will get a failure to fire because the the firing pin will not be able to contact the primer. If the headspace is too tight then you will experience other issues.

I have not seen it with AR's (simply because I follow the guidance) but I have seen it with M2 .50 cals.

Quote:

Originally Posted by Jimbo45

I have heard for so many years, to not swap bolts between guns, starting in the Army. I do keep my bolts in the guns that they came in, or I build them with, for really no other reason, than there being no need to swap them around, and this old advice from way back.

Using quality, in spec parts, I have never checked the headspace on anything I have put together or purchased, and have had no issues. Now if I had proper headspace gauges on hand, I probably would take the time to check, but I have never had the need, I guess.

But, has anyone, ever, heard of, seen, or personally experienced a problem, when swapping quality bolts or bcg's between uppers? I haven't. I could see that sticking a bolt with 40,000 rounds on it, in a barrel with a very long and loose chamber to begin with, might be an isssue. But, chances are, that barrel had a bolt in it, with as much wear anyway.

I don't understand the reasons for recommending to never put a new bolt in a xxxx round barrel. Maybe I am missing something, can someone explain the reasoning here?

Jimbo45 · #6 09-15-10, 18:48

Quote:

Originally Posted by Iraqgunz

The reason is simple. Excess headspace is a bad thing. Generally you will get a failure to fire because the the firing pin will not be able to contact the primer. If the headspace is too tight then you will experience other issues.

I have not seen it with AR's (simply because I follow the guidance) but I have seen it with M2 .50 cals.

I understand this. But, can someone explain how adding a new in-spec bolt to a barrel with some wear (when it functioned fine with the old, existing bolt), can cause excessive headspace, or not enough headspace?

Iraqgunz · #7 09-16-10, 16:13

Quite simple. New bolt= less usage, old bolt= more usage. Unfortunately I am not technically smart enough to explain it. I am sure that Quib could do it, though.

Quote:

Originally Posted by Jimbo45

I understand this. But, can someone explain how adding a new in-spec bolt to a barrel with some wear (when it functioned fine with the old, existing bolt), can cause excessive headspace, or not enough headspace?

Dano5326 · #8 09-16-10, 16:36

The lore of not mixing and matching bolts certainly has it's place in Belt Fed weapons, and older generation individual weapons, m14 etc. Where the mating surfaces take a beating and wear in together. It is of much less concern in an AR variant.

As a matter of course, preventive maintenance, I have dropped in new M4 bolts every 5K for years w/o issue.

The textbook and proper answer is to gauge it, the practical.......

Iraqgunz · #9 09-16-10, 17:21

I don't totally disagree. But, considering some of the manufacturers involved I say it is worth the little effort to check it whenever possible.

Quote:

Originally Posted by Dano5326

The lore of not mixing and matching bolts certainly has it's place in Belt Fed weapons, and older generation individual weapons, m14 etc. Where the mating surfaces take a beating and wear in together. It is of much less concern in an AR variant.

As a matter of course, preventive maintenance, I have dropped in new M4 bolts every 5K for years w/o issue.

The textbook and proper answer is to gauge it, the practical.......

luckyguy1 · #10 09-16-10, 20:12

only first hand experience I have is with an early 1980's bushmaster when I put a new BCG in it, it would not cycle wolf at all, but would usually function with brass.

now you can say what you want about wolf, or bushmaster, or new vs old bolts , but without scientific examination, in my case, it didn't work out very well.