[ny32182]

I just watched the videos of the barrel removal and installation, and it was a snap. Easier than I thought it would be. I am curious about a few things:

1) I noted that there was some thick-ish grease type lubricant, or something, on the exterior part of the barrel surrounding the chamber, that is engaged by the trunion. I didn't remove it... does this stuff have to be there? What is its function?

2) I like how the barrel nut never actually gets "loose" even when it is backed out... makes me think it will not easily shoot loose. However, when reinstalling the barrel, after the nut was "hand tight" (I take this to mean, once it encounters a little more resistance from the minimum as far as torquing it down) it would not turn another 70 degrees. So, I basically just torqued it down as tight as I could by hand. I'd say it was only about 30 degrees past the first "hand tight" spot. Is that alright?

3) How does the headspace work in this rifle/how do I know the barrel is truly seated properly? I did make sure to pay careful attention to the orientation of the gas block with relation to the upper, and matched it upon reinstallation, but as we know, headspace can be measured in thousandths.

4) In one of the videos, they talk about orienting the holes in the gas tube down for normal conditions, or up for shooting in "a sandstorm or muddy water"... what is going on there? Can someone expand on that a little?

Thanks.

 

[Phalanx]

You know that is a good question about the head spacing, i have wondered that myself.
The only thing i can see making it self adjusting is perhaps the bolt and the chamber lock up area are pre done .
This being the area where the bolt locks into the chamber is made onto the barrel and not a part of the main receiver.

 

[MickeyC]

1) No idea, but I have a small ammount on my barrel and it makes fitting it easier.
2) That works for me and mine has ony come loose once.
3) The bolt locks into the barrel extension and that governs headspace, as on an AR/AK etc... so don't worry about seating the barrel. that affects accuracy between changes.
4) No idea but it probably has more to do with keeping water out of the gas tube. As long as water isn;t trapped in between the piston and the gas plug you should be fine.

 

[ny32182]

Mickey, thanks, what sort of conditions caused your barrel to come loose? Did you make any changes in tightening procedure after that?

 

[MickeyC]

Probably badly fitted at the factory. I realized it was loose and followed the procedure and it's been fine since. It and the gasblock are two things I check regularly though, just in case.