Lastrites Wrote:In these times that's a very good price.

Nismo Wrote:Do these have the proper head spacing?

montana Wrote: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 Wrote: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 Wrote: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.

lazyengineer Wrote: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.

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Klem Wrote: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.

lazyengineer Wrote: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.

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montana Wrote:The opinions on using head space gauges are rather surprising and entertaining to say the least..

montana Wrote:No, I don't check my bolt action rifles that are factory built since they are tested before being sold.. I did learn the differences between throat sizes back in the late 80's when my factory Remington 300 Weatherby blew out the brass on the cases neck from extreme pressure with my custom loads that ran fine in my factory Weatherby rifle. The loads were not anywhere near the high end from my manual but it was my fault for not working my loads up with that particular rifle..Live and learn! Weatherby uses a longer throat than what Remington uses, much like the difference between the NATO 5.56 chambering and the commercial 223, so many disregard as unimportant.. My custom bolt rifles were chambered by my gunsmith using incremental gauges. All three short chambered 5.56 barrels function fine, meaning chambering, firing and extracting without a hitch, yet they won't pass the min 223 go gauge of 1.4636. Two of my AR short chambered 5.56 rifle barrels popped primers out, not pierce them..Pierced primers are usually a sign of excessive firing pin protrusion. One was on a semi auto with a Bushmaster barrel from the early 90's, the second was an Olympic Arms barrel on my class 3 that popped a primmer and lodge in the disconnect channel, which scared the dickens out of my nephew when it ran the full mag after he released the trigger. The third barrel is a 20" stainless fluted Sabor defense barrel that shoots extremely poorly. I blamed the ammunition for a long time for popped primers until I realized the barrels with this problem had short chambers. Amazing what a person can discover with a few gauges and know how. All of my 6.5 Grendel AR rifles are built by me and have passed my go-no go gauges..