View Full Version : new bolt/BCA in an old rifle. bad idea?
Are there any potential issues to watch out for if one decides to replace an old BCA with a new one? I've heard both ways (pro and con) and wonder if the membership here can get my mind right on this.
The "con" example I've heard is that the situation would be like putting new rings on your car's pistons without first chroming the cylinders. You get the idea.
Thanks.
The "con" example I've heard is that the situation would be like putting new rings on your car's pistons without first chroming the cylinders. You get the idea.
I don't know how that compares to a new bolt group. :confused:
It would depend on how OLD the upper/barrel is. If it's pretty old, you'd just have to have someone use a headspace guage on it to make sure it's good to go.
Are there any potential issues to watch out for if one decides to replace an old BCA with a new one? I've heard both ways (pro and con) and wonder if the membership here can get my mind right on this.
The "con" example I've heard is that the situation would be like putting new rings on your car's pistons without first chroming the cylinders. You get the idea.
Thanks.
no I don't get the Idea. you might want the hone the cylinders if your just changing rings,but no one has chromed cylinders in over 30 years and that was only on air cooled engins.you may know less about cars than AR's . a new bolt in an AR is no problem and is done all the time without any problems .:rolleyes:
no I don't get the Idea. you might want the hone the cylinders if your just changing rings,but no one has chromed cylinders in over 30 years and that was only on air cooled engins.you may know less about cars than AR's . a new bolt in an AR is no problem and is done all the time without any problems .:rolleyes:
guilty as charged, but FWIW I *was* thinking about engines like Conti's and Lycomings( air cooled motors, yes? ), not Chevy or Ford. I ASSume that the fact that you understood what I was getting at means that maybe you did "get the idea". :confused:
I am genuinely sorry if the analogy was not apt enough to pass muster with you. The same holds for my not having specified aircraft engines in my scenario from the above.
For demigod and others-
A buddy of mine who is a pretty good shade-tree AR wrench advised against replacing a BCA. He suggested just getting a whole new upper. His reasoning was that over time, the reciprocation of the BCA inside the upper *might* cause wear patterns specific to that BCA. A new BCA in the old upper might not wear the same, which could lead to some problems.
That seems possible, but I would think that the interior tolerances of the upper might not be so tight as to cause such wearing. Still, I don't know for sure and figured I would ask here at the forum.
From the tone of the previous response, I guess the answer to my question is pretty much a definite "no, it's not a bad idea". As always, any additional input would be appreciated.
you said cars
Clearly. Hence the apology.
Actually there is that pesky little issue of headspace. If you are putting a new bolt into an old upper receiver you will want to buy the correct type of guage and check it.
So then out of curiousity would an acceptable option be to swap out bolts on a gun if you have a new BCG (also new gun) and a spare bolt? That way they both wear evenly?
Are there any potential issues to watch out for if one decides to replace an old BCA with a new one? I've heard both ways (pro and con) and wonder if the membership here can get my mind right on this.
The "con" example I've heard is that the situation would be like putting new rings on your car's pistons without first chroming the cylinders. You get the idea.
Thanks.
The military replaces bolts all the time. Guys in Vietnam would bath their BCG's in buckets and didn't care who got who's when they re-assymbled rifles. Never heard a problem about it. That is why there is a spec for these things. If you have a properly spec'ed part, it will be just fine.
the whole time I was in country (1971-1972)I carried a spare BCG just in case ,and only needed it 1 time ,and I'm glad I did.
Yes, the military does replace bolts all the time and when we do we use a "Field" headspace gauge. Just because guys then didn't seem to know better doesn't make it right.
The military replaces bolts all the time. Guys in Vietnam would bath their BCG's in buckets and didn't care who got who's when they re-assymbled rifles. Never heard a problem about it. That is why there is a spec for these things. If you have a properly spec'ed part, it will be just fine.
won't the headspace on an AR increase as the bolt/barrel extension lugs wear?
so replacing the bolt only will add back some of that material to the bolt, reducing headspace.
now if you manage to wear a bolt out, you should certainly check your headspace.
but if anything installing a brand new bolt should bring overall headspace closer to spec?
am i missing anything?
Honestly, I try not to overthink things like this and I do what the manuals say in regards to headspace checks. Especially if you ever see what happens with a .50 cal that has improper headspace.
won't the headspace on an AR increase as the bolt/barrel extension lugs wear?
so replacing the bolt only will add back some of that material to the bolt, reducing headspace.
now if you manage to wear a bolt out, you should certainly check your headspace.
but if anything installing a brand new bolt should bring overall headspace closer to spec?
am i missing anything?
RogerinTPA
08-01-08, 17:30
Yes, the military does replace bolts all the time and when we do we use a "Field" headspace gauge. Just because guys then didn't seem to know better doesn't make it right.
Just curious since I'm not an armorer, but what are the corrections to be made when the head-space gauge determines BCG is out of spec with the weapon? The M2 seems a little bit easier to adjust the headspace on than a BCG on an AR platform. Will the armorer have to hand fit/custom fit the bolt to make it within spec?
I have allways replaced the barrel if a new in spec bolt won't head space,but there may be another way to do it I'm not aware of .:rolleyes:
In the military world this is the procedure that is used.
1. Replace old bolt with a new bolt and recheck the headspace. NOTE: New bolt is cheaper than a barrel.
2. If it fails again you rebarrel the weapon and recheck this time using the original bolt. If it passes you are good. NOTE: Barrel is the next most expensive
3. If it fails you then add a new bolt carrier assembly and recheck. This time it should obviously pass as the barrel and bolt are new.
Of course there are other checks that are done as well.
1. Firing Pin protrusion.
2. Barrel Straightness.
3. Bore Erosion.
4. Trigger pull.
5. Gage plug check (trigger and hammer pin holes) to check if they are worn.
Just curious since I'm not an armorer, but what are the corrections to be made when the head-space gauge determines BCG is out of spec with the weapon? The M2 seems a little bit easier to adjust the headspace on than a BCG on an AR platform. Will the armorer have to hand fit/custom fit the bolt to make it within spec?
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