Ultralight Ultralight Rifles

[PistolPete]

What was the issue with running it? Were your cases sticking? Mine run as easily as a typical bolt rifle, but faster. Fishdart also posted a while back about sticking cases. Wonder why some do and some don't...?

I've only seen any sticking with the 30 HRT...
I'm not sure why bigger cases tend to be stickier.

My guess is more friction from more surface area of the case, and increased thrust expanding the case more tightly into the chamber and binding the bolt, but not sure, and I only have experience with that one larger case.

I have run my lightweight gasser like you describe and that works fine. The disadvantage is that I have to run it from the charging handle, which isn't too ergonomic. (Actually, I guess you mean running it semiauto - that works too - takes very little gas to run, but runs fine)

I guess the cases were sticking; tried it with 300 Blk and 223, and it just takes a lot of force to open and eject. With the 223, I'd have to bump the buttstock on the ground while pulling back on the bolt to get it to eject.

I didn't mean running the gasser as a straight pull from the charging handle; I meant running it as a semi auto, just tuning it to run on less gas through the gas block since I've removed ~8 oz of weight from the cycling parts (alum BCG and buffer with weights removed). Will experiment more with this setup.

 

[Thegman]

I guess the cases were sticking; tried it with 300 Blk and 223, and it just takes a lot of force to open and eject. With the 223, I'd have to bump the buttstock on the ground while pulling back on the bolt to get it to eject.

I didn't mean running the gasser as a straight pull from the charging handle; I meant running it as a semi auto, just tuning it to run on less gas through the gas block since I've removed ~8 oz of weight from the cycling parts (alum BCG and buffer with weights removed). Will experiment more with this setup.

Yeah, that's a head scratcher, especially with 300 BLK. Are you running with a suppressor?

 

[PistolPete]

Yeah, that's a head scratcher, especially with 300 BLK. Are you running with a suppressor?

No, haven't taken that step yet!

 

[Thegman]

No, haven't taken that step yet!

So much for that hypothesis...

Sorry to hear it's not working like it should. I've run 7 barrels on 3 different solos and the only one that acted like that was the 30 HRT barrel. 223 Wylde, 5.56, 300 HAM’R, 300 BO and 350L have all extracted effortlessly, with zero issues at all...not that that helps you at all...hmmm.

Grasping at straws here...I do grease my bolt lugs on my ARs pretty liberally. I don't know how much if any this helps, but worth a try if you don't already.

One other question: How easy is it to extract an unfired cartridge after chambering?

 

[Taudisio]

So much for that hypothesis...

Sorry to hear it's not working like it should. I've run 7 barrels on 3 different solos and the only one that acted like that was the 30 HRT barrel. 223 Wylde, 5.56, 300 HAM’R, 300 BO and 350L have all extracted effortlessly, with zero issues at all...not that that helps you at all...hmmm.

Grasping at straws here...I do grease my bolt lugs on my ARs pretty liberally. I don't know how much if any this helps, but worth a try if you don't already.

One other question: How easy is it to extract an unfired cartridge after chambering?

Sometimes I would love to get my hands/eyes on them to try and diagnose the potential problem(s) so I could avoid it for my own rifle. Diagnosis over the web without photos/exploration proves difficult

 

[packgoatguy]

I think Thegman is right about the increased surface area of the 6mm ARC case. He's also correct about the extractor tension causing issues when chambering. When I removed the O-ring from my 5.56 bolt, it helped a lot. I expect that was part of the issue with my 6mm ARC barrel too.

All that said, the 6mm ARC is still viable in a straight-pull if it's the cartridge you want. It likely won't be as easy to cycle as a 5.56-based case, but so what?

Good insight! I'm actually leaning towards the 22ARC. I've been impressed with the 77tmk factory loads out of my 16 inch 223wylde giving me 2771fps... so I figure that the extra case capacity would get me solidly into the 2950fps or better range by comparison... that would really extend my range. Maybe try the 88 eldm for some better wind bucking capabilities...

Where is the best place to look for the lightest possible AR barrel in 6ARC, 22ARC, 6.5Grendel, etc? Any pencil barrel options like the 19.5oz faxon?

 

[packgoatguy]

I posted a pic of my carrier earlier. You can see it's liberally coated with grease which is how I run it, maybe with a couple drops of clp to thin it a little. I'm just using thin red grease intended for lubing a chainsaw bar. Any thin grease would probably work fine.

Thanks for the advice! It helped a lot! Much smoother now.

 

[StupidLightweight]

I'm with you on the .22 ARC. I see one in my future as well. Paired with 88 ELD-Ms, this might be the ultimate big-game hunting setup.

Don't even look at factory barrels. Call an AR barrel maker and have a custom one built without the gas port. It'll cost more, but it will be done right. If the barrel is heavier than you like, have a local machinist/gunsmith turn it down further.

 

[Silent_Matt]

Update on trying to plug the barrel gas hole... the JB weld and aluminum rings held for about 10 shots. I then tried adding a lot more JBweld around the edges, still using the aluminum rings... probably a good 1/8 inch thick of the epoxy around it. That failed in one shot. So I cleaned the jbweld all off to bare metal, removed the rings. I tried just installing a steel gasblock upside down, just to see what it would do. Still got leakage (put silicone around all the seams so I could tell). I was going to try to find a tap small enough to get a bolt in there, but then I found a tiny machine screw that was just skinny enough that I could get it to thread into the existing hole... so, I applied a bit if the 24hour 5k psi jbweld, on the screw and threaded it in. I used my borescope to make sure I didn't screw the bolt in too far. Then after that epoxy cured, cut the exposed head ic the screw off flush with the top of the barrel, and used jbweld to put a piece of aluminum tube back over it. So far this has held up for 12 rounds.

In hindsight, I should have just used a tap and put a real bolt in from the get go.

The good news is this faxon barrel is shooting awsome! Under MOA so far. Surprisingly easy to shoot. I'm glad I upgraded the trigger.

Still holding at 64.6oz not including the suppressor. 79.4oz including suppressor and tripod.

I have about 60 rounds with the steel sleeve and retaining compound(Loctite 635) now, and no gas leaks.

 

[Taudisio]

Well she came out heavier than anticipated. Right at/under 53oz. I swapped the grip for the hogue so hopefully that dropped an ounce. The only thing I’m waiting on is the gas block. I’ve racked my brain about all the different options. I think I’m going to stick with a steel block turned backwards so I can set it and forget it, instead of always worrying about aluminum eroding. Should add another .6 oz. I greased the snot out of the bolt and it is night and day smoother. Going to shoot it without the block tomorrow to get on paper and some starting data. My guess is 58-59oz with a full 10 round magazine. I can’t believe how light and balanced it is. Feels like a loaded glock when I bring it up with two hands on the grip.

 

[ztc92]

Really enjoying following along on this thread. I only have one AR and it’s about 10 pounds and built to be very durable but I now foresee one of these in my future.

Has anyone built one with a 1913 rail instead of a buffer tube to allow for a lightweight folding stock? Thinking a 14.5” barrel with a pin and weld + folding stock at about 4.5 pounds would be pretty great to tote around in a backpack.

 

[ztc92]

Read up on this a bit further, came across some lowers that are sold with 1913 rails and/or adapters such as the BRN-180 and PSA Jakyl.

Thinking this lower from PSA could be a great value to build off. The lower with parts and 1913 adaptor is 9.5 oz. The stock per JMAC website is 5.4 oz. I’m assuming the folding mechanism is around 3 oz but can’t find an answer. If so, the entire lower + folding stock is ~18 oz. for a price of $300.

https://palmettostatearmory.com/blem-psa-jakl-complete-rifle-lower-5-56-nato-moe-ept-skeleton-stock-fde.html

Add a Solo300 upper ($275, 12 oz), faxon 14.5” pencil barrel (~$150, 18oz) and a lightweight handguard (~$300, ~5 oz) you’d be at about $1,025 and 53 oz. From there, would just need a muzzle device to P&W and some way to block the gas port. Guessing you’d be all done at around $1100 and ~56 oz with a folding stock included. Would make a great lightweight suppressor host too.

 

[ztc92]

One additional thought I had while thinking on this…

If the 6ARC is hard to extract due the slightly different case dimensions and/or increased pressure, then if someone wanted a 6mm bolt AR-15, perhaps the 6x45 would be an option and extract easier? Curious if anyone else has tried or considered this?

 

[Thegman]

Really enjoying following along on this thread. I only have one AR and it’s about 10 pounds and built to be very durable but I now foresee one of these in my future.

Has anyone built one with a 1913 rail instead of a buffer tube to allow for a lightweight folding stock? Thinking a 14.5” barrel with a pin and weld + folding stock at about 4.5 pounds would be pretty great to tote around in a backpack.

Take a look at StupidLightweight's build(s). He has experience with folding stocks on these. I think there is at least one other folder on this thread.

 

[Thegman]

One additional thought I had while thinking on this…

If the 6ARC is hard to extract due the slightly different case dimensions and/or increased pressure, then if someone wanted a 6mm bolt AR-15, perhaps the 6x45 would be an option and extract easier? Curious if anyone else has tried or considered this?

All the 223 based stuff has extracted easily for me and (most) others. The 6x45 will extract fine. Probably even easier than 223. From what I've seen so far, for a given parent case, the larger the caliber, the easier the extraction, though the difference is fairly small relative to using a larger diameter parent case.

 

[packgoatguy]

Read up on this a bit further, came across some lowers that are sold with 1913 rails and/or adapters such as the BRN-180 and PSA Jakyl.

Thinking this lower from PSA could be a great value to build off. The lower with parts and 1913 adaptor is 9.5 oz. The stock per JMAC website is 5.4 oz. I’m assuming the folding mechanism is around 3 oz but can’t find an answer. If so, the entire lower + folding stock is ~18 oz. for a price of $300.

https://palmettostatearmory.com/blem-psa-jakl-complete-rifle-lower-5-56-nato-moe-ept-skeleton-stock-fde.html

Add a Solo300 upper ($275, 12 oz), faxon 14.5” pencil barrel (~$150, 18oz) and a lightweight handguard (~$300, ~5 oz) you’d be at about $1,025 and 53 oz. From there, would just need a muzzle device to P&W and some way to block the gas port. Guessing you’d be all done at around $1100 and ~56 oz with a folding stock included. Would make a great lightweight suppressor host too.

You can be cheaper and lighter sticking with a buffertube style lower and folder:

TNA Carbon Lower; 4oz $30
NFA poly LPK (minus grip): 2oz $36
Hogue 15degree vertical grip: 1.52oz, $19
V7 Ti grip screw; 0.107oz, $11

Total lower weight: 7.627oz
Total lower cost: $96
(You can save another 0.543oz by using the MDT Carbon grip, which is only 0.977oz, but it costs $139... or you can
Skeletonize the Hogue grip to get close to the same weight savings, so final Lower weight is 7.084.

Add the IMI kidon folder stock: 6.5oz, $82

IMI Defense Kidon Folding Stock Adapter Up to 18% Off w/ Free S&H — 4 models

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Final total weight of lower, including folding stock: 13.584oz
Final total cost: $178 before shipping.

If you don't mind "DIY" you can make your own stock from carbon fiber tube (rockwest composites, Amazon, etc), attach it to the cut off threaded end of a normal buffer tube stock, and make some sort of butt end for it. Mine turned out great using a dense foam and thin carbon fiber stays. Only 3.1oz. Then add a BTFA folder adapter (3.4oz, $100). Total weight at 6.5oz, total cost including the folder adapter can be kept under $150... but you get a more rigid stock and can get your exact LOP, cheek height, etc.

For the handguard... the lightest "advertised " option is the JAG composites one, $250 for the 7.5inch one... however mine weighed in at 2.0oz instead of the advertised 1.7oz, so I sent it back... and made my own... a simple 7.5 inch carbon fiber tube is only 1.25oz. But I do like the JAG composites barrel nut at .82oz, $45, and their little ti screws (bag of 8 for $35) but if you get the right size carbon tube, it will be a tight enough fit over the barrel nut that only one or two little screws would be necessary. I attached a 0.6oz mini ARCA rail from wiser precision, and thin carbon fiber support rails from carbon arrows, and I'm not more than the actual weight of the JAG handguard, and after sourcing a single screw at my local hardware store... I'm less than $90 including barrel nut, jbweld, carbon tube, and less than $120 including the arca rail...

 

[Thegman]

You can be cheaper and lighter sticking with a buffertube style lower and folder:

TNA Carbon Lower; 4oz $30
NFA poly LPK (minus grip): 2oz $36
Hogue 15degree vertical grip: 1.52oz, $19
V7 Ti grip screw; 0.107oz, $11

Total lower weight: 7.627oz
Total lower cost: $96
(You can save another 0.543oz by using the MDT Carbon grip, which is only 0.977oz, but it costs $139... or you can
Skeletonize the Hogue grip to get close to the same weight savings, so final Lower weight is 7.084.

Add the IMI kidon folder stock: 6.5oz, $82

IMI Defense Kidon Folding Stock Adapter Up to 18% Off w/ Free S&H — 4 models

Shop IMI Defense Kidon Folding Stock Adapter | Up to 18% Off Be The First To Review IMI Defense Kidon Folding Stock Adapter + Free Shipping over $49.

www.opticsplanet.com

Final total weight of lower, including folding stock: 13.584oz
Final total cost: $178 before shipping.

If you don't mind "DIY" you can make your own stock from carbon fiber tube (rockwest composites, Amazon, etc), attach it to the cut off threaded end of a normal buffer tube stock, and make some sort of butt end for it. Mine turned out great using a dense foam and thin carbon fiber stays. Only 3.1oz. Then add a BTFA folder adapter (3.4oz, $100). Total weight at 6.5oz, total cost including the folder adapter can be kept under $150... but you get a more rigid stock and can get your exact LOP, cheek height, etc.

For the handguard... the lightest "advertised " option is the JAG composites one, $250 for the 7.5inch one... however mine weighed in at 2.0oz instead of the advertised 1.7oz, so I sent it back... and made my own... a simple 7.5 inch carbon fiber tube is only 1.25oz. But I do like the JAG composites barrel nut at .82oz, $45, and their little ti screws (bag of 8 for $35) but if you get the right size carbon tube, it will be a tight enough fit over the barrel nut that only one or two little screws would be necessary. I attached a 0.6oz mini ARCA rail from wiser precision, and thin carbon fiber support rails from carbon arrows, and I'm not more than the actual weight of the JAG handguard, and after sourcing a single screw at my local hardware store... I'm less than $90 including barrel nut, jbweld, carbon tube, and less than $120 including the arca rail...

Sounds like you are making some cool stuff; I like the ideas. Can you post some pictures of your work?

 

[packgoatguy]

Sounds like you are making some cool stuff; I like the ideas. Can you post some pictures of your work?

4lbs 15.4oz as shown, including suppressor, tripod, scope, and folding stock. Sub moa with 77gr tmk, 2751fps.

 

[Thegman]

4lbs 15.4oz as shown, including suppressor, tripod, scope, and folding stock. Sub moa with 77gr tmk, 2751fps.

That's ridiculously lightweight considering everything you have there. 1.4 oz heavier than my bare Kimber Montana.

 

[packgoatguy]

That's ridiculously lightweight considering everything you have there. 1.4 oz heavier than my bare Kimber Montana.

This build has just reminded me about how unnecessarily "heavy" most rifles really are... I've got my kimber hunter 308win cut down to 16 inches, minimalist on the stock, etc, and with the same scope, tripod, and suppressor as on the AR, it's about 6lbs 2oz. At most I could shave off another 3-4oz or so with a fluted barrel like the ascent, ti action screws, ti bolt knob, and going crazy with skeletonizing the stock more... maybe 5oz if someone could come up with a poly mag to replace the stupid factory steel one that kimber makes... but I could also shave another oz or two off of the AR with a ti charging handle, and skeletonizing the upper. Plus. If I'm really comparing apple to apples... I'd remove the 3.4oz folder adapter from the AR15 and add the couple ounces for a 22 cal barrel on the kimber. Realistically, the AR will be a good pound lighter than the lightest traditional bolt action out there, assuming you are truly comparing apples to apples...

Although I would say, i suppose it would be possible to find a kimber 84m Action set up with a 223 bolt, and then have a true pencil profile barrel made for it... like the AR pencil barrels... that would probably shave 6-8 ounces off of the factory kimber profile barrel... maybe then, plus some aggressive fluting of the bolt and action you could get a bare kimber rifle in a 22cal down to 3lbs... seems like @StupidLightweight did something like that with his kimber in a 6mm Creedmoor.