Ultralight Ultralight Rifles

[robtattoo]

With my new 6x45 barrel, I'm less than an ounce over 4lb now, with 5 in the mag

 

[SoFLBeachBum]

I first found this thread nearly two years ago, I was searching for lightweight gasser builds. I came back to this thread and actually read it. Now I’ve gone and built an ultralight bolt action straightpull. I blame you all.

 

[Tailwind5sw]

I applaud the dovetail and latcjh!! Now cut a grove in the rail matching the mount clamp, than drill and counter sink the bottom and screw the pa riser to the upper with out the clamp!

 

[SoFLBeachBum]

I’m built it using spare parts from a gasser carbine. I saw the ATL opp straightpull, I read about the Solo here, and had the idea to do one but reuse the charging handle latch. I built the gas key/latch from a piece of 10mm by 15mm aluminum and another 8mm by 25mm price, hollowed it out and installed a latch. Several months later, my little monster was built:

 

[SoFLBeachBum]

I applaud the dovetail and latcjh!! Now cut a grove in the rail matching the mount clamp, than drill and counter sink the bottom and screw the pa riser to the upper with out the clamp!

I almost did that! Instead I filed the bottom of base to clear the charging handle. But I did add two more grooves to the rail (the Microprism now sits closer to my eye)

 

[Thegman]

Fantastic job, @SoFLBeachBum !

I really like seeing all these great ideas.

 

[SoFLBeachBum]

Fantastic job, @SoFLBeachBum !

I really like seeing all these great ideas.

Thank you, TheGman, for the praise! You started all this. Turning the AR15 into the ultimate ULUL took some original thinking. I’m grateful you did it and shared it. And it’s awesome so many have joined in and keep the idea growing. I hope this thread gets pinned.

 

[Thegman]

My best UL-UL experiment to date:

My "hypothesis" was that the long throats on 5.56 and 223 Wylde chambered barrels might be reducing accuracy and consistency, especially with trying to load longer bullets like the 75, 80 & 88 ELDM and now 88 TMKs. With AR mags, the jumps most bullets have to take in a 5.56 barrel, especially the previous four, is ridiculous.

The more I thought about it, the more I thought these rifles should be treated more like a bolt rifle with more typical bolt rifle chambers rather than 5.56 and 223 Wylde AR-15 type chambers.

I thought about just getting a standard 223 Remington chambered barrel, but figured I might lose too much velocity having so much less chamber volume with the shorter throat. Figured a 223 Ackley Improved might be the best of both worlds; less throat length, but more chamber volume. Seems to be working.

My X-Caliber 223 AI arrived and I've been shooting it some, mostly fireforming, but a few loads through formed brass as well. The barrel is 0.57" profile diameter and 22.2 oz, so not terribly heavy, but heavier than most I've been using.

I didn't try to shave any weight putting it together. Figured I'd start heavy and lighten later if I wanted to. I used a 4.5 oz Kaw Valley handguard rather than my 1.9 oz version so together with the lower I've been using, the bare rifle is 3# 5oz - a veritable pig of an UL-UL.

Also has an Airlock Nano screwed on, which only weighs 3.6 oz with the 1/2x28 thread adapter. I'm far from a suppressor expert, but I think this is THE suppressor for a 22 caliber UL-UL.


So...enough of hearing me blah, blah, blah...how does the damn thing shoot?

Well, not only better than any UL-UL I've ever built, but literally, better than any rifle I've ever owned, including all the Tikkas I've ever owned.

So far, there's no load development, there's just load picking. The hardest part so far is deciding what you want to shoot; everthing shoots more than well enough.

This was about an hour ago, messing with 88 TMKs @ 2.325" (and one at 2.365") trying to find max reasonable velocity. This is 5 shots, 5 different loads using 3 different powders (Shooter's World Match, CFE 223 and 2000 MR)



See what I mean?

This is several (typical) fireforming loads with 77 TMKs. No load development. Just seeing what velocity I'd get from various powders.






Okay, you probably get the point...

Anyway, apologies in advance. You'll probably have to listen to me go on about this set-up for a while. However, if you're thinking of building one (or another one), I do think going to bolt rifle type chambers will, on average, pay big dividends over sticking with AR based chambers.

 

[SoFLBeachBum]

Thegman, you're getting sub MOA while fireforming the cases? I have no experience reloading much less fireforming, but that sounds impressive.

 

[ACHILLES]

Still working on the UL UL gasser but here it is currently. Planning to get it even lighter. Sent in a 16” pencil barrel off a bushmaster carbon15 and had it cut to 13”
I’m running frontier 556 68bthp at 2770fps shot 2 5shot groups while sighting in at 100yds. They went .9” & 1.1” shooting off bags standing.

Waiting on the form 1 to clear for my poly tegra lower that’s much lighter.

Right now running a 2A Palouse lite receiver set, tubbs flat wire spring, taccom 1.5oz buffer, smoke comp buttstock, superlative steel adj gas block, jag carbon handgaurd kit, ASC 10rd Al mag. With PA 3x sight with 45degree PA SLX RS-10R and Airlock ZG6.5 with an ls wild cover. Sits at 5.1lbs all up now but when I’m able to put the Tegra lower on, take the red dot off, use a smaller riser for the prism scope, replace the barrel with a BCA ultralight cut down to 12”.
It will put me at 3.8lbs for a scoped, suppressed gas gun. And 3.1lbs for bare rifle with mag.

Even now it’s pretty easy to freehand my 12” plate at 200yds.
I also tried the nova x nas3 55gr copper hp’s they run 3050fps out of the 13” bbl. And for the hell of it I shot 3rnds of the frontier 556 75gr bthp and they avg an impressive 2630fps. Something strange is that same lot of 75bthp’s avg 2615fps in my tikka 16” 223rem with a 3” longer barrel. I’ve put about 100rounds through it so far and liking it a lot.

 

[Thegman]

Thegman, you're getting sub MOA while fireforming the cases? I have no experience reloading much less fireforming, but that sounds impressive.

Yes, with this particular barrel, I'm getting sub-MOA for 3, 5, even 10 with everything so far. Even M855 Green Tip shot 1" for the three I shot, which is probably about as good as anything will shoot that stuff.

This is a continuation of the target I posted a couple of days ago. This is now 10 shots over three days, testing powders and loads. It's now 4 powders (SW Match, CFE 223, 2000 MR and LVR)
and 8 different loads (shot 2 loads twice). Velocities from 2626 to 2717 with the 88TMK.


I should have done this a long time ago, but I'm a dummy.

This barrel and rifle set-up has been a final proof-of-concept of these rifles.

1. With the correctly chambered, quality barrel, and proper set-up, these rifles have almost uncanny accuracy potential.

2. Light rifles are not particularly difficult to shoot if #1 is taken care of. I can shoot this rifle as well or better than any rifle I've ever owned, including those that weigh 2x+ as much. It's extremely easy to shoot. In fact, so far, it's difficult not to shoot well.

My advice - don't waste time with barrels chambered specifically for AR-15s. Spend a little more money on a quality barrel with a chamber that meshes well with 2.3ish" COAL. You will VERY quickly make the money back in load components or very quickly finding great shooting factory ammo, and probably a much larger selection of ammo that shoots well in your rifle.

 

[proslogion]

What vise block is everyone using when tinkering with these builds?

I was going to just pick up a cheapo, but then I watched a break down from School of the American Rifle and got really in my head about making sure the upper never twists, etc... and I was thinking it probably _really_ matters with the plastic lowers.

 

[robtattoo]

Amazon.com

I've had one of these for a while. No problem that I'm aware of on 6 different uppers. It is a distinct tighter fit in the SOLO upper than any of my others.

 

[4090Sharps]

What vise block is everyone using when tinkering with these builds?

I was going to just pick up a cheapo, but then I watched a break down from School of the American Rifle and got really in my head about making sure the upper never twists, etc... and I was thinking it probably _really_ matters with the plastic lowers.

For your upper work, I'd recommend getting a receiver rod. Here's the one I use:

Upper Receiver Rod

The AR-15 Upper Receiver Rod is the ultimate tool for barrel nut installs or removal, and is excellent for removing stubborn/seized barrel nuts without damaging the upper. Made by Midwest Industries. Shop All AR Upper Parts & Receivers.

midwestindustriesinc.com

 

[Thegman]

What vise block is everyone using when tinkering with these builds?

I was going to just pick up a cheapo, but then I watched a break down from School of the American Rifle and got really in my head about making sure the upper never twists, etc... and I was thinking it probably _really_ matters with the plastic lowers.

I'm still using the plastic upper block (kind of like what @robtattoo posted, but nylon) I bought from NFA when I first started and knew even less than I do now.

Now I would get something like these. A reaction rod with an extension that interfaces with the gas key slot. These are the "gold standard", I think especially the midwest industies.

Upper Receiver Rod

The AR-15 Upper Receiver Rod is the ultimate tool for barrel nut installs or removal, and is excellent for removing stubborn/seized barrel nuts without damaging the upper. Made by Midwest Industries. Shop All AR Upper Parts & Receivers.

midwestindustriesinc.com

Amazon.com

The plastic lower doesn't matter as you're never torquing the lower (or shouldn't be). There are blocks that insert into the mag well of the lower, but they're only for holding the lower in a vice while assembling LPKs, etc.

 

[ACHILLES]

Amazon.com

I've had one of these for a while. No problem that I'm aware of on 6 different uppers. It is a distinct tighter fit in the SOLO upper than any of my others.

This is the one I’ve been using for all my ar’s, it’s aluminum and extends up in the gas key slot.

 

[Thegman]

Amazon.com

I've had one of these for a while. No problem that I'm aware of on 6 different uppers. It is a distinct tighter fit in the SOLO upper than any of my others.

Some of my Solos are tight, one really tight on my nylon block as well. I suspect yours works better than my nylon block as there's probably no movement of an aluminum block. The nylon can flex a tiny bit when torquing a barrel nut to 40+#. Seems to have been okay so far, but doesn't seem ideal.