Hi guys, I don't post much but have been enjoying Arfcom for years. I have learned a lot from the technical forums and appreciate everyone who passes on their experience to newbs like me.

I recently bought a CMMG Mk3 .308, my first ar-10/lr.308. I took it home and field stripped it and cleaned it. Fit and finish were pretty good but I noticed that the bolt had no tension between it and the carrier. In other words, while holding the carrier bolt down the bolt would fall forward with just gravity or when the bolt was engaged in the barrel extension and the upper was turnef barrel up, the bolt carrier would fall right out.

In the several ar-15s I've owned there was quite a bit of friction between the bolt and carrier, enough that I had to pull hard to pull the bolt forward away from the carrier. I could also pull the bolt forward, place the bolt and carrier bolt down and the weight of the carrier would not overcome the friction and compress.

So I guess what I'm asking is if my new .308 bolt should feel like a 5.56 bolt, or is the .308 supposed to feel more loose. Is it my gas rings or is the hole to big?

Unfortunatly, I won't have a chance to shoot it for a few weeks.

bump

There should be some friction, it's not enough to hold the carrier up as on an ar15 cause the carrier is heavier but enough for the bolt to stay up if the other way around. More than likely it's the rings although it could be the bore or a combination of the two. I would fire the rifle and see if it cycles. There is generally plenty of gas with 308 so I doubt you will have a problem. A lot of 5.56 guns are soo over gassed they will run without rings.
I put a bit of grease on all my rings anyway and you can try that if you want. If it doesn't cycle you can try new rings but if it's a factory built rifle I would be calling cmmg. Either way I would fire it before worrying about it. Try some low power loads if you really wanna test it.

Good info, thanks!

I called CMMG about this same issue on my MK3 CBR.  They said that is how they send them out.  I asked the standard well should t it hold the bolt carrier up, straight answer was nope.  Mine runs great about 500 rounds in and no issue.  Go shoot and let that thing eat, I'll bet it does great.

Good to hear, thanks for the reply.

Just to follow up. I shot my Mk3 today. Only 20 rounds but it went bang everytime and ejection was consistent at about 3 o'clock.

Only problem was having to max out the windage on my rear sight to get it on paper. Looks like my barrel is not straight.

The bolt on my LR-308 is exactly the same way. Functions 100%. It initially concerned me too but my concerns were unwarranted. And, my bolt is a really nice JP Enterprises version.