Aim ar/m16 6.5 grendel nitride 9310 mpi bdg bolt carrier group $89.95

[Happy2Shoot]

AIM AR/M16 6.5 GRENDEL NITRIDE 9310 MPI BDG BOLT CARRIER GROUP $89.95

https://aimsurplus.com/aim-ar-m16-6-5-grendel-nitride-9310-mpi-bdg-bolt-carrier-group/

If you need one.

[Lastrites]

In these times that's a very good price.

[montana]

In these times that's a very good price.

Depends on how they are made whether it is a good price or paper weight. I have a plastic tub full of good priced failed bolt carrier groups. I'm very suspect without first doing an inspection and putting some gauges in it. Buyer beware!

[drewthebrave]

I have had great experience with 5.56 BCS from Aim Surplus (Nitride Milspec, and NIB Skeletonized). No personal experience with their Grendel offerings, but I'd be willing to give them a shot!

[Lastrites]

AIM's customer service is pretty good as well, have never heard of them not standing up for the products that they sell.

[raamaudio]

I have ordered many times from AIM and have always been completely satisfied with their branded products and service.
Their titanium carrier was in the super lite 4.2lb 12" pistol I built, it was very well machined, perfectly coated and a bit lower in price than competing products.
I put an upper together this week with the nickle boron regular BCG in 65G, I think it was $129, looked as good as any I
have ever bought no mater the price, will see how it works out, sure just fine.

Rick

[Nismo]

Do these have the proper head spacing?

[montana]

Do these have the proper head spacing?

Unless you purchase a barrel and bolt already head spaced together, you will need to use a go and no gauge to verify head space with the bolt you intend to use.

[Klem]

Unless you purchase a barrel and bolt already head spaced together, you will need to use a go and no gauge to verify head space with the bolt you intend to use.

Nismo,

I think differently and would instead cautiously fire the first round from the hip while briefly looking away (obviously pointing in a safe direction). I do that with all new barrels anyway. You can even wear gloves and hold it away from your body if concerned.

With AR's, headspace is fixed by the gunsmith who chambered that barrel. He/she would have used gauges and a bolt. Obviously not the same bolt you have but it will be pretty close. The most likely scenario is that it will be fine. The other two scenarios are too much headspace, or not enough headspace.

Too much headspace
With too much space the case expands and ruptures. When that happens it will split about halfway along the case separating it into two halves. There will be a louder than normal bang, more smoke out the action than normal, and it will leave a circular trench mark in the chamber. The front half of the case might need some fiddling with a pick to get it out. Or it might just come out with an oversized cleaning brush. At that point you take it back for a refund - providing you used factory rounds for the firing. If you use handloads for the first firing they could refuse, as it could be your fault in how you headspaced the case in the first place, and/or how much powder you loaded.

If the case ruptures from too much headspace don't forget the the gun is still in battery. The case is designed to take some of the pressure, while the bolt lugs are designed to take the rest. The case will absorb some of the pressure prior to rupturing and the bolt lugs will do their thing. The likelihood it will be a catastrophic event that hurts you is remote, especially if you fire the first round from the hip.

Not enough headspace
If this, then the bolt won't close on factory ammunition and you take it back for a refund. Even if your chamber is slightly less than SAAMI and it fires it is perfectly safe. If the bolt does not close on a factory round then it can't fire and that is safe too.

GO/NO GO gauges cost money so you will need to weigh up the need, and part of that is wondering how often you will use them, and the gun. If you have calipers you can figure out the chamber dimensions by measuring the spent cases.

One last point, this is a different scenario to handloading too much powder into a case and rupturing the gun from overpressure. If in the unlikely event your new chamber has too much headspace the factory cartridge will not be overpressured. The rearward force on the case as it splits will represent overpressure on the lugs (only), but a lot of that pressure will have been absorbed in the split first. It's not like you are pulling the trigger on a grenade. I have experienced two case separations from too much headspace; it was handloader error (me), but it is the same scenario you are concerned about. Although there was smoke and a bit of surprise at the time the same gun with two separations still fired normally after.

[montana]

I have three short chambered 5.56 barrels from reputable manufacturers on my shelf I won't use. I keep them as examples. I have one 5.56 barrel that will barely pass the go gauge with a short bolt.One bolt may pass head space with a particular barrel while a different one won't. This is why it is prudent to check head space with the bolt being used with the barrel.. Everyone of those short chambered barrels would chamber rounds reliably. I got into a debate with the Brownelles gunsmith Caleb over this very same subject, which he became very insulting. I noticed he has since removed that video after I gave references and names to do his home work lol. He didn't even know the proper 5.56 go gauge length for the 5.56 NATO chamber. I won't even get into the throat length debate. Short chambers are much more common than over length chambers in my experience. Short chambers will increase pressure and impede reliability. Telling people they don't need to check head space on the AR platform is irresponsible in my opinion, especially when many will push the envelope with reload pressures. Head space gauges cost money, but reconstructive facial surgery or worst could be even more expensive. This is my advice and people can do as they wish with their rifles, since I'm not the one shooting a rifle with out checking head space first..

[Klem]

MOntana,

I have a Lilja chamber from the original group buy that is fractionally over SAAMI. From measuring spent cases it would likely not pass the gauge test. All Lapua rounds do not split on the first firing however and from then on they get .003": bump, I have lost count how many firings each case has but it will be over 10. Sized cases do not pass a rifle gauge as they are too proud but they all fire normally and I am comfortable I know what is going on.

I don't doubt some techniocian insulted to you and did not know as much as they should. I will never insult you. I am simply coming from a different perspective and weighing up the risk. I believe you have far more chance blowing your face off reloading rounds than firing the first factory round through a new barrel at the hip. Every time we fire a rifle it is a risk - some trigger pulls' are riskier than others.

I note you prefer different lubes and liquids and are very particular about it. I use motor oils and greases, and WD40 white lithium on triggers and suppressors. I am simply offering an alternative view from similar experience.

[montana]

MOntana,

I have a Lilja chamber from the original group buy that is fractionally over SAAMI. From measuring spent cases it would likely not pass the gauge test. All Lapua rounds do not split on the first firing however and from then on they get .003": bump, I have lost count how many firings each case has but it will be over 10. Sized cases do not pass a rifle gauge as they are too proud but they all fire normally and I am comfortable I know what is going on.

I don't doubt some techniocian insulted to you and did not know as much as they should. I will never insult you. I am simply coming from a different perspective and weighing up the risk. I believe you have far more chance blowing your face off reloading rounds than firing the first factory round through a new barrel at the hip. Every time we fire a rifle it is a risk - some trigger pulls' are riskier than others.

I note you prefer different lubes and liquids and are very particular about it. I use motor oils and greases, and WD40 white lithium on triggers and suppressors. I am simply offering an alternative view from similar experience.

Klem,
For some reason there can be a lot of egos or hurt feelings involved when sharing firearm knowledge or opinion. Yes, he did throw out a lot of insults in my direction which was quite amusing since he was proven wrong and then deleted the whole video. I have no financial skin in this game and just enjoy the process of learning. Using a comparative and OAL gauge is reasonable and I'm still experimenting with one to test chamber sizes instead of the cost prohibitive incremental .001 gauges, but standing with a rifle while holding it at waste level and looking away does not sound like a great way to test the safety of a rifle, "but hey" that's me. We all have our own ideas of what is safe and the risks we are willing to take to save a buck. For the cost of a go and no go gauge, it is a sound investment IMO. I also think safety chaps and a hard hat is an important investment when using a chainsaw, even though I have never cut myself in the many, many, decades I have used one. I have worked in some of the most dangerous occupations my entire life and was never seriously injured or had an employee hurt when many others were not so lucky. I like to think things through and try to see and prevent hazards before they occur. Like I said before, each to their own..

[Old Bob]

If anyone reading this thread wants 6.5 Grendel NO/NO-GO headspace gauges, Brownells has Manson gauges in stock. You'll have to scroll down the list to find them. I think the price for them is fair at $40.00 each.

https://www.brownells.com/gunsmith-tools-supplies/measuring-tools/headspace-gauges/rimless-rifle-shotgun-cartridge-headspace-gauges-prod25179.aspx

[Nismo]

They also have a type 2 bolt. Which has the proper 0.136 bolt face? for type 2 barrels

Nismo,

I think differently and would instead cautiously fire the first round from the hip while briefly looking away (obviously pointing in a safe direction). I do that with all new barrels anyway. You can even wear gloves and hold it away from your body if concerned.

With AR's, headspace is fixed by the gunsmith who chambered that barrel. He/she would have used gauges and a bolt. Obviously not the same bolt you have but it will be pretty close. The most likely scenario is that it will be fine. The other two scenarios are too much headspace, or not enough headspace.

Too much headspace
With too much space the case expands and ruptures. When that happens it will split about halfway along the case separating it into two halves. There will be a louder than normal bang, more smoke out the action than normal, and it will leave a circular trench mark in the chamber. The front half of the case might need some fiddling with a pick to get it out. Or it might just come out with an oversized cleaning brush. At that point you take it back for a refund - providing you used factory rounds for the firing. If you use handloads for the first firing they could refuse, as it could be your fault in how you headspaced the case in the first place, and/or how much powder you loaded.

If the case ruptures from too much headspace don't forget the the gun is still in battery. The case is designed to take some of the pressure, while the bolt lugs are designed to take the rest. The case will absorb some of the pressure prior to rupturing and the bolt lugs will do their thing. The likelihood it will be a catastrophic event that hurts you is remote, especially if you fire the first round from the hip.

Not enough headspace
If this, then the bolt won't close on factory ammunition and you take it back for a refund. Even if your chamber is slightly less than SAAMI and it fires it is perfectly safe. If the bolt does not close on a factory round then it can't fire and that is safe too.

GO/NO GO gauges cost money so you will need to weigh up the need, and part of that is wondering how often you will use them, and the gun. If you have calipers you can figure out the chamber dimensions by measuring the spent cases.

One last point, this is a different scenario to handloading too much powder into a case and rupturing the gun from overpressure. If in the unlikely event your new chamber has too much headspace the factory cartridge will not be overpressured. The rearward force on the case as it splits will represent overpressure on the lugs (only), but a lot of that pressure will have been absorbed in the split first. It's not like you are pulling the trigger on a grenade. I have experienced two case separations from too much headspace; it was handloader error (me), but it is the same scenario you are concerned about. Although there was smoke and a bit of surprise at the time the same gun with two separations still fired normally after.

I'll put this into consideration!

[lazyengineer]

Pretty much what KLEM said. I'm not going to say it's a bad idea to check headspace. But the reality is that incorrect headspace doesn't Kaboom like people act. It results in a broken shell and jammed gun. THe back portion of the break will swell enough to seal the chamber, and you don't actually get a big pressure release. Too tight a chamber (more common), results in bolt that wont' rotate, and so firing pin that won't reach, and so a "click", and that's it.

Neither is A-OK, and is at best a PITA. And things going wrong, always elevates risk of more things going wrong. So yea, checking with gages is great. But don't think it's some insane crazy cavalier risk to take parts that shoudl be in spec, assemble, and fire. On top of that, I've studied (and once even witnessed), enough AR Kabooms, to realize the system is quite well engineered. AR Kaboms dont' sent huge fragments into the shooters head (unlike say a 1903 or homemade .50 cal Kaboom!). AR15 Kabooms result in minor scratches, hand brueses, and sometimes skin deep minor bleeding. Most AR15 Kabooms are from .300BO in 5.56 guns, and from excessive pressure loads, and from barrel obstructions. Pretty much never seen or read of one due to headspace, that I can tell. As always, wear eye protection for every round fired, regardless!

FWIW, your fired brass well tell you your chamber size as well, especially steel. So if you have calipers and the Hornady headspace test rings that mount on them, that works decent enough too.