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Posted: 11/10/2016 9:36:31 AM EDT
| So i have a rifle with about 700 rounds through it, BCM barrel and fail zero bcg. I just bought a BCM bcg and want to throw it in that rifle and use the failzero in another one I am building. Is that alright or do i need to check headspace? thanks for the help. |
| Seeing the reply on two different head space gauges makes me wonder: If the .223 and 5.56 round max length is the same and the barrel/chamber is a 5.56 what would the difference in head space be in my case? I only have 5.56 barrels/chambers and only load to .223 loads as I don't really need a few extra feet per second and the higher PSI for paper targets, as they don't run very fast. How could I get into head space issues just loading to max length and lower pressure loads? Trying to understand this subject more than I do now. Never thought about this. |
| So pretty much what i'm getting out of this is when a barrel and bolt are paired up they should pretty much stay together ? Also, I hear a lot on the forum of guys who have issues with their rifles for various reasons and people comment on changing BCG with one that is proven or swapped from another rifle they have. Wouldn't they need to check the headspace as well, and what does shooting the rifle change as far as headspace goes? Just trying to wrap my head around this stuff. i appreciate all the help. I've done some reading and just confused myself. I want to make sure everything i'm reading from other resources is correct. The amount of info that comes from here is just amazing. thanks |
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A 99.9% chance that the bolt is good to go on your rifle. The AR15 bolt is good to go unlike older rifles.
However, it is a wise idea to check it. You'll want a combination of a go/no-go, or a go/field gauge. You'll need to buy the guage and the tool to disassemble the bolt. The total cost for these tools are about 100-150 range. You can go to a gun smith and have it checked for maybe 10 bucks or so. Here's the trick: 1) If the bolt closes on a no-go and a go, then it is not good to fire if the bolt is brand new. However, if you had a rifle for years upon years, then it is fine if the bolt closes on a no-go, but you'll want to check if it closes on a field gauge which means it has reached the end of its service life. Chances are, as a recreational shooter, you'll never reach the point where a bolt will close a no-go. 2) Make sure the gauges are all from the same company. It is entirely possible to get a false positive if you use different companies. 3) All this takes a minute or two to do. Never close a bolt with force other than by finger pressure. Do not try to jam, shove, or force anything to go into battery. Always use finger pressure, and stop immediately once you feel pressure. If you slam the bolt with the gauge in, it may damage your barrel. |
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Quoted:
So pretty much what i'm getting out of this is when a barrel and bolt are paired up they should pretty much stay together ? Also, I hear a lot on the forum of guys who have issues with their rifles for various reasons and people comment on changing BCG with one that is proven or swapped from another rifle they have. Wouldn't they need to check the headspace as well, and what does shooting the rifle change as far as headspace goes? Just trying to wrap my head around this stuff. i appreciate all the help. I've done some reading and just confused myself. I want to make sure everything i'm reading from other resources is correct. The amount of info that comes from here is just amazing. thanks Generally speaking the military manuals always warn not to swap bolts. When the military asks for their rifles to be built, there's a good chance the bolts can be interchanged without issue since the M1 Garand was introduced. That's the main battle rifle like the M16, M1 Garand, etc could all be swapped freely but some of the off weapons had to get their bolts fitted into the receiver. For example, the M14 has a good chance the bolt will headspace right but since the receiver is so hard to make, some recent manufacturing of the rifle may cause short or excessive headspace and thus extreme pressure. With that said, AR15s are a completely different animal. The bolt headspace correctly 99.9% of the time. I have several ar15 rifles, all custom built, sometimes with swapped out bolts but I always head space it before firing. I have not once experienced a situation where the headspace was out of spec, not even close. They all stop on a no-go correctly and close on a go. Also keep in mind it is common for special forces soldiers to carry a extra bolt with them. If their main bolt fails, which can happen, they'll be able to swap it out fast. It's very doubtful they would be checking headspace in the middle of battle. The reason why people suggest swapping with a known good BCG is to check for excessive gas leak on the carrier. Especially when the rifle is failing to lock back or not picking up the next round. It's a "one step at a time" solution. Start with going backwards: new magazine, bolt carrier, etc, etc. Find a point where it "works" with all the existing component then most likely you found the failure. It has nothing to do with headspace in this context. |
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Quoted: Just remember they have 556 and 223 gauges. A 5.56 NATO head space gauge set will work in .223 Remington and .223 Wylde and vice-versa. Compatibility chart from Pacific Tool and Gauge for their .223 Remington head space gauges:
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| I appreciate all the feedback. I understand why people swap out carriers and I get the whole process of elemination thing but it just seems people swap out bcg more freely when they have an issue with their rifle. I really wanted a field gauge but they aren't in stock anywhere so I ordered a set of go/nogo from brownells. |
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Quoted:
Almost forgot, what would be signs of a headspacing issue on a spent case ? Spent cases would have: 1) Blown out primers 2) Deep gouge marks 3) Ripped, bent, or cracked cases 4) On a ar15, if excessive pressure is there, it could blow the magazine out of the mag well. Here's the problem: #2 and #3 can be caused by a really strong extractor spring usually with a o-ring. It can also be caused by overgassed which can be cured with a new buffer spring. Personally I wouldn't stress it too much. Also, no, people don't frequently swap out complete bcg or bolts. It's just silly and just because people suggest it doesn't mean it's standard practice. Don't listen to everything you read on this website and assume it is true. Remember, anyone can sign up for this site, and you don't know who might be an expert or just someone who searched it on google. As always ask yourself this question: Does it work? If it works, then don't worry about it. It's not like you got a ticking timebomb or something. If it works 100 times, it'll work 1000 times. Trust me, you'll know where there is an issue. You don't have to "find" it to know it. |
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I wouldn't. Using two decent quality parts, there shouldn't be any issue. Wear your eye pro first couple shots I guess, if it makes you feel better? I still wouldn't.
Now the lower end barrels I wouldn't buy to begin with, should be checked. Or better yet, not bought. I minimize how much I switch out BCG's as once they've been used a while, they wear in specific to the carrier. A different carrier will wear in a little different than the last. That wear in is exponential more compared to the wear it gets from shooting after that. I also like to keep bolts at least with barrels, as they wear on the barrel extension. The only swapping I do like that is with my MRP's, but as little as possible. |
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