Ultralight Ultralight Rifles

[Thegman]

I do have a question about how much everyone is torquing the barrel nuts down. With the 5.55, I torqued it, a lot, but not as much as my semi-autos with a torque wrench. I watched some of the solo videos and they basically hand tighten them and barrel swap in the field. I wouldn’t feel comfortable THAT loose. Just curious what everyone else has done.

I don't generally measure my torque and don't have any exact numbers, but do tighten a lot more than hand tight. Probably in the 20-30 (max) ft/lb range.

I had to tighten a Jag Composites nut quite a bit more than I normally do to get it to line up so I measured that one to be sure I wasn't over tightening the nut. I found my normal tightening by "feel" was a good bit lower than max AR barrel nut tightening specs. I'd personally rather be under than risk damaging something by over tightening. Enough that everything is "snug" and won't loosen, but that's about it.

 

[robtattoo]

I picked it up on a local gun owners forum. The guy used it for a .300blk pistol & decided to go a different route. Being a "single shot" none of the rednecks around here were interested so it sat & sat, getting cheaper & cheaper until I couldn't justify not buying it anymore.

 

[JBradley500]

I torqued 30, backed off, 30 backed off, then finally 40. The mass produced guns where the glass tube needs to pass through the barrel nut teeth are just cranked on until they get the opening to line up. I bet a lot of those are in the 60-80 range at times.

I also have heard accuracy is better with some decent torque because the upper will be squeezed tightly to the barrel extension and be similar in tension to a press or thermal fit.

 

[JBradley500]

Also, anyone think of 6max?

 

[Rich M]

View attachment 697403

Had to sight in again since I changed the mount for the Romeo 5. Put 5 shots into 1.35" at 100. I really can't argue with that since I can barely see the target, and I'm just trying to center the dot over the outer part of the black circle. Edit - 2628 fps average with the 77tmk with compressed varget. That'll do for my ranges.

I have a Romeo 5 and the dot is too small for me. Had it on a 357 mag rifle and would get about a soda can bottom group. I'd rather have a 2.5 inch or 5 inch dot for being able to see it. Went with a bushnell banner 4x and shoot 8-inch plates out to 200 with it. The heavy circle reticle is much easier to see than the little dot.

 

[JBradley500]

I am keeping my eyes out for the upcoming Primary Arms GLX 1x microprosm. I think it's got a few months before it's available to the public though. That might be a good piece for these setups, although I like the Romeo so far.

 

[robtattoo]

Also, anyone think of 6max?

I mean, I am now.....

 

[Thegman]

I torqued 30, backed off, 30 backed off, then finally 40. The mass produced guns where the glass tube needs to pass through the barrel nut teeth are just cranked on until they get the opening to line up. I bet a lot of those are in the 60-80 range at times.

I also have heard accuracy is better with some decent torque because the upper will be squeezed tightly to the barrel extension and be similar in tension to a press or thermal fit.

Maybe I should quit being a wuss and torque a little more, just to check accuracy differences if nothing else.

 

[Thegman]

Also, anyone think of 6max?

Ha, I was just about an hour ago. Still waiting for better availability and beta testers.

 

[PistolPete]

Ha, I was just about an hour ago. Still waiting for better availability and beta testers.

Unless I'm missing something, and assuming both are the same level of availability (not very), the 6 Max seems like a complex way to use more expensive brass and still end up with basically a 6 TCU - which uses .223 brass.

I do like the idea of a 6mm, but longer case lengths don't mate well with AR mag restrictions and heavy bullets. The ARC case wins there for sure (save for the straight pull extraction issue).

Now, if the Dark Mountain Stowaway came in a 6 TCU, you'd get cheap brass, longer OAL, and light rifle. But not a repeater...

 

[PistolPete]

Also, I just learned about Rossi's break open polymer action single shot pistol (Brawler, just over 2 lbs) and rifle (Tuffy, ~3 lbs) in 45/410. If a fella wanted a way to launch heavy subsonic .452 slugs, he could likely use .444 brass expanded to .45 (see 450 Mongo)...

 

[robtattoo]

Unless I'm missing something, and assuming both are the same level of availability (not very), the 6 Max seems like a complex way to use more expensive brass and still end up with basically a 6 TCU - which uses .223 brass.

I do like the idea of a 6mm, but longer case lengths don't mate well with AR mag restrictions and heavy bullets. The ARC case wins there for sure (save for the straight pull extraction issue).

Now, if the Dark Mountain Stowaway came in a 6 TCU, you'd get cheap brass, longer OAL, and light rifle. But not a repeater...

The only downside to the TCU is that you kinda have to stick to heavy, long bullets simply because of the throating. I guess you could have a barrel short throated, but then you're back to a 6x45.

I didn't realize the Max had to be made from .350, I thought it was just necked up .223, like the x45, but with a steeper shoulder & shorter neck

 

[Thegman]

The only downside to the TCU is that you kinda have to stick to heavy, long bullets simply because of the throating. I guess you could have a barrel short throated, but then you're back to a 6x45.

I didn't realize the Max had to be made from .350, I thought it was just necked up .223, like the x45, but with a steeper shoulder & shorter neck

Yes, it looks like they changed nothing about the 350L case other than necking it down to 6mm. I'm not sure of the die steps it would take trying to do that with a 350L case, which are at least very available (but not anything close to 5.5.56 cases)

A couple years ago I did mock up some 30-350L cases just to look at case capacity. Might make a decent "300 HAM’R Magnum", but not worth the trouble to me to actually do it.

The 6mm Mongoose looks to be about as close as you could get, functionally, to a 6mm Max in an AR platform, while still using a 5.56 case. Same as 300 HAM’R compared to the hypothetical "30-350L".

 

[Taudisio]

I am keeping my eyes out for the upcoming Primary Arms GLX 1x microprosm. I think it's got a few months before it's available to the public though. That might be a good piece for these setups, although I like the Romeo so far.

I haven’t heard of the glx 1x microprism. I have seen the slx 1x microprism and they have a tan version in stock. If the glx is something new, I’m listening!!!

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Details This Primary Arms MicroPrism is part of the SLx optics line. SLx optics have built a reputation for innovation, reliability, and value. All SLx optics undergo rigorous field-testing during development to best serve you in any environment. The SLx® 1x MicroPrism is an all-new advanced...

www.primaryarms.com

 

[JBradley500]

Yeah it was something brought to shot show but isn't releasing for a while yet.

 

[Taudisio]

Yeah it was something brought to shot show but isn't releasing for a while yet.

I wonder what difference it will have from the slx besides push buttons over a knob? I did a google search, it sounds promising with “much better glass”. It would be neat to see them side by side!

 

[180ls1]

Is there any sort of consensus for a build parts/kit for guys who are keeping their AR semi-auto?

 

[Thegman]

I can't speak for a consensus, but for my 3#10oz gasser, the key parts were an Aero no forward assist upper, Jag Composites ultralight handguard, DSA aluminum bolt carrier, adjustable gas block, no weights in the buffer and other lightweight parts pretty much the same as my straight pull builds.

 

[180ls1]

I can't speak for a consensus, but for my 3#10oz gasser, the key parts were an Aero no forward assist upper, Jag Composites ultralight handguard, DSA aluminum bolt carrier, adjustable gas block, no weights in the buffer and other lightweight parts pretty much the same as my straight pull builds.

Cool. Was the adjustable gas block "needed?"

Whats your take on it for hunting as opposed to the straight pulls?

 

[Thegman]

Cool. Was the adjustable gas block "needed?"

Whats your take on it for hunting as opposed to the straight pulls?

I think it's probably needed, but never tried it without. With the lightweight bolt carrier and buffer they take -very- little gas to run. I say that because my Superlative Arms gb once blew out it's adjustment screw so it was in 100% "bleed-off" mode and the rifle still ran fine, maybe even a little over-gassed. I'd guess that if they're run without an adjustable gb they might beat themselves up pretty bad, but I haven't tried it.

They're great for hunting, IMO, just a little heavier, and more finniky with respect to loads as the gas requirement is so low. I think they should probably be tuned to the load, it seems easy to over-gas them. Also, it's obviously harder to keep track of brass for reloading if you reload.

The only advantages for me has been less recoil and faster follow-up shots. Neither of those have been very important to me in my typical hunting situations and I seldom use it anymore. It has taken a couple of deer and a big black bear though.

All that said, I'm planning on testing the 77TMK on a grizzly later this spring, and I've been thinking the auto-loader just might be a good idea in that particular scenario...I'll sacrifice a few pieces of brass in that case, if necessary.