Ultralight Ultralight Rifles

[Trackselk]

Mine are all new cases. I was under the (incorrect) impression that your new cases wouldn't chamber, so nothing to do with my neck thickness idea. I doubt the neck has enough contact to affect extraction after firing as long as the round chambers.

The cases are sticking for some other reason, possibly what you're thinking with length. It could also be that they're just "stickier" than brass cases and need more force to extract than the Solo system provides, like it's inability to extract with larger diameter cases. A gasser has way more extraction force which is why gassers work with those larger cases as well.

I think that this "stickier case" might be the actual problem. Sometimes I have a case that's sized a little too long for a particular rifle and have to pull the Solo bolt all the way back and smack the bolt forward to get it to go into battery. Those cases are stuck in tightly enough that they're pretty much jammed in and are really difficult to extract without firing. Once fired though, they extract fine, almost like they rebound enough to fit more loosely. These NAS cases may just react and extract very differently than the brass cases we're used to using.

When I get time, maybe today, I'll run a couple through a Solo, a BCA, a gasser and my Tikka to see if there are differences in extraction.

Good thoughts. I think I vetted the length theory out with a ton of measurements, and it was fine. Then, as for the stickier idea, they are actually slicker, which is part of their appeal, especially for smooth running gas guns. After being fired, you can easily feel that they're too big for the chamber, and the case gauge helped me narrow it down to the shoulder, if I'm not mistaken. Here's a Pic of a new case sticking up .001" over max. So, add one thousandths of case stretch to the fired case and it's holding significant pressure against the bolt face. Phantom has seen a couple instances of this with bolt guns also, although we didn't get into the exact reasons for it.
I should have documented my measurements better in a devoted thread when I started trying to figure this out. But, multiple theories are better anyhow...

Edit: and if anyone isn't familiar with the case gauge tool, the other end is open, so the neck is free to extend through/not affecting the measurement in the pic. Or, in other words, this is a measurement of shoulder to the case head.
Looking at the other end, You can see if the neck is too long or short, which it isn't.

 

[Thegman]

Good thoughts. I think I vetted the length theory out with a ton of measurements, and it was fine. Then, as for the stickier idea, they are actually slicker, which is part of their appeal, especially for smooth running gas guns. After being fired, you can easily feel that they're too big for the chamber, and the case gauge helped me narrow it down to the shoulder, if I'm not mistaken. Here's a Pic of a new case sticking up .001" over max. So, add one thousandths of case stretch to the fired case and it's holding significant pressure against the bolt face. Phantom has seen a couple instances of this with bolt guns also, although we didn't get into the exact reasons for it.
I should have documented my measurements better in a devoted thread when I started trying to figure this out. But, multiple theories are better anyhow...

Edit: and if anyone isn't familiar with the case gauge tool, the other end is open, so the neck is free to extend through/not affecting the measurement in the pic. Or, in other words, this is a measurement of shoulder to the case head.
Looking at the other end, You can see if the neck is too long or short, which it isn't.
View attachment 855313

Shot three of the NAS cases loaded with 26 grains of LVR under a Hornady 75BTHP at 2.280" OAL
1ea through my UL-UL with a BCA Pencil barrel, Tikka T3 and BCA upper
All cases were 1.755" long before firing
All extracted okay (the Solo was sticky but manageable, but a lot more difficult than it would be with a brass case and the same load)
All rechambered okay (Solo was a little tight)
Tikka case grew to 1.760" in length, the other two to 1.767"
All cases very sooty, so not expanding much during firing

I'd say your guess about the cases wedging themselves in the chamber between the shoulder and base is probably correct. Need to measure the outer case dimension and compare to a typical brass case expansion, but suspect it will be fine there. This wasn't a terribly hot load. I imagine if it was, the cases would lengthen enough to lock up the Solo and at least start getting sticky in the other two.

Additional info:

I measured the base of the cases to see how much they expand after one firing. Figured not much with all the soot I saw on them...wrong once again...!

Measuring just above the base part of the case, the cases start around 0.370" - 0.371", which is smaller than a typical 223 case which would be around 0.372" to 0.374". The cases measured between 0.376" to 0.377" after firing, which is quite a bit larger than a brass case (LC) would typically be, around 0.374" to 0.375" in these rifles.

I don't think this was enough expansion to cause sticking due to their diameter, but shows they do stretch a lot compared to brass cases and I imagine that's what is wedging them in the chamber. The case fired in the Tikka expanded the most (0.3770" - No brass case has ever expanded that much in that chamber), but it didn't stick on lifting the bolt. The brass fired in the BCA pencil barrel was a little smaller in diameter (~0.3767"), but wouldn't chamber in the Tikka, so the issue was most likely the length dimension stretching that was the issue with trying to chamber it, and probably what's causing the sticking in the Solo.

These things are just weird...

 

[Welldone]

This may not be acceptable but I have my latest builds listed for sale/trade in gun classified.
Thanks

 

[C Bow]

If these cases are steel when we shoot them in a AI chamber and blow the shoulders out they may split instead of stretch that much. Brass is soft enough to stretch and form a new chamber. I ask a couple engineers that today and they agree that is a good possibility I will discuss with gunsmith this weekend.

 

[Trackselk]

If these cases are steel when we shoot them in a AI chamber and blow the shoulders out they may split instead of stretch that much. Brass is soft enough to stretch and form a new chamber. I ask a couple engineers that today and they agree that is a good possibility I will discuss with gunsmith this weekend.

That's a good point. I was thinking that I'd risk it, but now I think I'll start with a reduced load and wouldn't want to send you those full power loads until I know that they're safe. It's one thing to blow up my own stuff...

 

[C Bow]

I have quite a bit of experience with AI rifles but I am for sure not saying I know everything about them . With that said like the 7mm.08 AI I built I would fire regular 7mm 08 Winchester ammo in it and it would blow case
out to form shoulder but it has always been brass . Then I would neck size for reloading. I do not have any experience with the cases that you are talking about but will help in any way I can.

 

[C Bow]

I bought some Winchester ammo to shoot and make my AI cases as soon as I get barrel Then I will weigh them and see how much capacity I can get in them I told Smith to throat them to shoot 77 gr as the lightest bullet I would shoot in it

 

[Trackselk]

Shot three of the NAS cases loaded with 26 grains of LVR under a Hornady 75BTHP at 2.280" OAL
1ea through my UL-UL with a BCA Pencil barrel, Tikka T3 and BCA upper
All cases were 1.755" before firing
All extracted okay (the Solo was sticky but manageable, but a lot more difficult than it would be with a brass case and the same load)
All rechambered okay (Solo was a little tight)
Tikka case grew to 1.760", the other two to 1.767"
All cases very sooty, so not expanding much during firing

I'd say your guess about the cases wedging themselves in the chamber between the shoulder and base is probably correct. Need to measure the outer case dimension and compare to a typical brass case expansion, but suspect it will be fine there). This wasn't a terribly hot load. I imagine if it was, the cases would lengthen enough to lock up the Solo and at least start getting sticky in the other two.

Thanks for the feedback. Just to clarify, that's the bca bolt action you tried?
I'm guessing your solo has about .001" more headspace than most. Could you actually open the action by hand? In mine, once I got to about 2500fps with 62 grain bullets and loaded long (2.36" / less pressure), it took something pounding on the handle to open it. PGG reported something similar.

On another front, the local well respected gunsmith told me he's seen a lot of AR's blown up with hot loads, and he won't build me an AI chamber for the strait pull, but sounds like he will for the bolt action setup. Regardless of the stronger cases not exploding, he's too concerned it will break the bolt and potentially cause injury or death. I think I'll listen to him and use the bca bolt action for hot loads. Just figured I'd pass thing along. He thinks 77 grain tmks at 2800-2850 in a 16" barrel is way too dangerous due to the wimpy bolt and aluminum uppers. Haven't phantom and some other ammo makers been pushing them about 2700 in our 16" barrels? @packgoatguy

 

[Trackselk]

I bought some Winchester ammo to shoot and make my AI cases as soon as I get barrel Then I will weigh them and see how much capacity I can get in them I told Smith to throat them to shoot 77 gr as the lightest bullet I would shoot in it

Thanks for the info and willingness to help on this project! What do you think of the notion of shooting the nas3 cases out of the AI chamber (if they don't split) in order to lower the pressure to a safer peak? I'm thinking that even if I only get one firing, that the case will expand to the bigger chamber, thereby lowering the pressure, and giving the 2900-3k fps (77-80gr bullets) dream a good chance with a better margin of safety.
Basically the 10% extra capacity and higher pressure capability of the nas3 cases might give us the Ai performance without going to the second step of the fire forming. Just a bonus if they are actually usable after fire forming.
Add the bolt action upper for yet another safety margin.

 

[longrangelead]

FWIW
I'm not familiar with the cases you are talking about, however I've done a ton of wildcat AR's, both 15's and 10's. I have found AR's don't like high pressure at all. much over saami and they get grumpy.
AR's have less metal in every area compared to a true bolt action. less metal=more potential for deflection.
two theories expressed here match what I have experienced. one, a long case can be chambered thus preloading the lugs. after firing, case growth adds more pressure against the bolt nearly locking up the action. A steel case may not spring back as much as brass either.

the other is excessive pressure does the same thing. AR's have a lot of surface area for lug interface, however the lugs and lug abutments are very shallow compared to a true bolt action. bolt thrust is bolt thrust.

The bigger the case, the thinner the chamber walls, the lower pressure it takes to see issues.
so steel or hybrid cases only give you the ability to run more pressure at the web. I doubt steel reduces chamber wall pressure significantly enough to allow 70k let alone 80k in a AR.

it's an easy thing to prove. reduce pressure until everything works. at that point, it is what it is.

I did a 338 RCM AR-10. Factory ammo sticks in the chamber and binds the bolt. if I pulled the bullet, reduced the powder by 2gr, it ran perfect.

I'm also not familiar with the BCA bolt action AR. If it has a true bolt action type lug system, it may handle bolt thrust better, if the tenon and chamber are the same diameter as a standard AR, it may not handle chamber pressure any different.

just my 2 cents...

 

[Trackselk]

FWIW
I'm not familiar with the cases you are talking about, however I've done a ton of wildcat AR's, both 15's and 10's. I have found AR's don't like high pressure at all. much over saami and they get grumpy.
AR's have less metal in every area compared to a true bolt action. less metal=more potential for deflection.
two theories expressed here match what I have experienced. one, a long case can be chambered thus preloading the lugs. after firing, case growth adds more pressure against the bolt nearly locking up the action. A steel case may not spring back as much as brass either.

the other is excessive pressure does the same thing. AR's have a lot of surface area for lug interface, however the lugs and lug abutments are very shallow compared to a true bolt action. bolt thrust is bolt thrust.

The bigger the case, the thinner the chamber walls, the lower pressure it takes to see issues.
so steel or hybrid cases only give you the ability to run more pressure at the web. I doubt steel reduces chamber wall pressure significantly enough to allow 70k let alone 80k in a AR.

it's an easy thing to prove. reduce pressure until everything works. at that point, it is what it is.

I did a 338 RCM AR-10. Factory ammo sticks in the chamber and binds the bolt. if I pulled the bullet, reduced the powder by 2gr, it ran perfect.

I'm also not familiar with the BCA bolt action AR. If it has a true bolt action type lug system, it may handle bolt thrust better, if the tenon and chamber are the same diameter as a standard AR, it may not handle chamber pressure any different.

just my 2 cents...

Many thanks for that. It would be interesting for someone with lots of time to test the burst pressure of brass vs nas3 cases with no chamber support. The more I learn, the more I'm dialing back my expectations for AR velocity.
The bca bolt doesn't have a different design for the lugs, mil spec AR bolt. the only additional safety it has is the bolt handle tucked down in a reinforced pocket. It's probably enough to save your face if the bolt sheared, but I don't want to find out.
At only 10% over 5.56 pressures, I'm not afraid of 70k, but the tough part is knowing when you're there. Wish I had a conversion for lever powder for the calculators...

 

[longrangelead]

Many thanks for that. It would be interesting for someone with lots of time to test the burst pressure of brass vs nas3 cases with no chamber support. The more I learn, the more I'm dialing back my expectations for AR velocity.
The bca bolt doesn't have a different design for the lugs, mil spec AR bolt. the only additional safety it has is the bolt handle tucked down in a reinforced pocket. It's probably enough to save your face if the bolt sheared, but I don't want to find out.
At only 10% over 5.56 pressures, I'm not afraid of 70k, but the tough part is knowing when you're there. Wish I had a conversion for lever powder for the calculators...

pressure isn't always linear powder to powder. I've found QL is off both directions I don't assume max is max without working up.
Maybe UM will by a pressure transducer and test all our dumb ideas!

 

[Trackselk]

pressure isn't always linear powder to powder. I've found QL is off both directions I don't assume max is max without working up.
Maybe UM will by a pressure transducer and test all our dumb ideas!

Yeah, better safe than sorry for sure. I wouldn't load these things as hot as a bolt action unless I had a long string and a lead sled. And, even then, the next one out hunting might be your last...
I'm thinking of limiting myself to 200 fps over factory rounds (clocked in my rifle), with nas3 cases, bca bolt action, and the bigger Ai chamber, and loaded out to 2.395" OAL, so I'm guessing the pressure will be very similar. I think that will get me about 2900 if the nas3 cases cooperate. If I have to scratch them, then I'll dial it back to 2800ish if no heavy bolt lift. This is with 79 grain DRT's.
I already went up to 3k fps with 62gr bullets with a 5.56 chamber and the nas3 cases.
-Thats all based on the reports of 2700 fps 77gr factory loads, if my memory serves me correctly???

 

[longrangelead]

Yeah, better safe than sorry for sure. I wouldn't load these things as hot as a bolt action unless I had a long string and a lead sled. And, even then, the next one out hunting might be your last...
I'm thinking of limiting myself to 200 fps over factory rounds (clocked in my rifle), with nas3 cases, bca bolt action, and the bigger Ai chamber, and loaded out to 2.395" OAL, so I'm guessing the pressure will be very similar. I think that will get me about 2900 if the nas3 cases cooperate. If I have to scratch them, then I'll dial it back to 2800ish if no heavy bolt lift. This is with 79 grain DRT's.
I already went up to 3k fps with 62gr bullets with a 5.56 chamber and the nas3 cases.
-Thats all based on the reports of 2700 fps 77gr factory loads, if my memory serves me correctly???

that all sounds realistic. I'm running 73' @2840 in my Tikka 223.
85's @ 2800 in my 6x45 AR

I both 223 AI and 6x45 AI AR's but haven't done more than fireform/function test either.

Honestly, I'm kinda over AR's and the mag restrictions.

I can barely keep enough ammo loaded for my bolt guns, let alone having some fun with semi autos.

 

[Trackselk]

that all sounds realistic. I'm running 73' @2840 in my Tikka 223.
85's @ 2800 in my 6x45 AR

I both 223 AI and 6x45 AI AR's but haven't done more than fireform/function test either.

Honestly, I'm kinda over AR's and the mag restrictions.

I can barely keep enough ammo loaded for my bolt guns, let alone having some fun with semi autos.

Thanks for the info based on experience, nothing beats it!
As for fun, I got a box of green tips at cabelas the other day, and was really happy when I got home and realized that they were in the hard to find LC cases! Too bad I had just bought some beat up once fired ones.

Mag restrictions, you can go 2.39" ish with windowed mags, and beyond 2.4" if you get after it with a file.

 

[Thegman]

Thanks for the feedback. Just to clarify, that's the bca bolt action you tried?
I'm guessing your solo has about .001" more headspace than most. Could you actually open the action by hand? In mine, once I got to about 2500fps with 62 grain bullets and loaded long (2.36" / less pressure), it took something pounding on the handle to open it. PGG reported something similar.

On another front, the local well respected gunsmith told me he's seen a lot of AR's blown up with hot loads, and he won't build me an AI chamber for the strait pull, but sounds like he will for the bolt action setup. Regardless of the stronger cases not exploding, he's too concerned it will break the bolt and potentially cause injury or death. I think I'll listen to him and use the bca bolt action for hot loads. Just figured I'd pass thing along. He thinks 77 grain tmks at 2800-2850 in a 16" barrel is way too dangerous due to the wimpy bolt and aluminum uppers. Haven't phantom and some other ammo makers been pushing them about 2700 in our 16" barrels? @packgoatguy

Yes, a BCA upper with their heavy 5.56 barrel, a Solo with a BCA pencil barrel and a Tikka. The only one that was sticky was the Solo, but it only took some 'snap' on the bolt handle to get it open, no hitting it or anything.

No offense about your gunsmith, but there's no more risk with an Ackley chamber than a standard chamber in any of these rifles, or any rifle for that matter. Also, some, or even a lot of the issues a gasser can have with letting go may not be applicable to these manual ARs. Gassers are starting to unchamber the round while there is still pressure on the system and that may open up a lot of other variables these don't face (though I suppose if they're timed correctly, the bullet should be gone along with barrel pressure well before the bolt unlocks).

Not sure why he thinks the same bolt and barrel would be okay on the BCA and not the Solo, other than an aluminum bolt carrier vs steel bolt carrier and the bolt handle in the receiver (?). Maybe that's his thinking?

I think I've mentioned this, but I do have several loads that hit 2,700 and bit with the 77TMK out of a 16 inch barrel. That's been no problem in my rifles, but after messing with the NAS cases, and obviously lot's of experience with brass cases, 2,800+ is not something I would try. FWIW, after trying the NAS cases I think your best bet for max 223 velocity in the Solo would be a 223 AI with brass cases.

 

[Trackselk]

Yes, a BCA upper with their heavy 5.56 barrel, a Solo with a BCA pencil barrel and a Tikka. The only one that was sticky was the Solo, but it only took some 'snap' on the bolt handle to get it open, no hitting it or anything.

No offense about your gunsmith, but there's no more risk with an Ackley chamber than a standard chamber in any of these rifles, or any rifle for that matter. Also, some, or even a lot of the issues a gasser can have with letting go isn't applicable to these manual ARs. Gassers are starting to unchamber the round while there is still pressure on the system, that opens up a lot of other variables these don't face.

Not sure why he thinks the same bolt and barrel would be okay on the BCA and not the Solo, other than an aluminum bolt carrier vs steel bolt carrier and the bolt handle in the receiver (?). Maybe that's his thinking?

I think I've mentioned this, but I do have several loads that hit 2,700 and bit with the 77TMK out of a 16 inch barrel. That's been no problem in my rifles, but after messing with the NAS cases, and obviously lot's of experience with brass cases, 2,800+ is not something I would try. FWIW, after trying the NAS cases I think your best bet for max 223 velocity in the Solo would be a 223 AI with brass cases.

Thanks for the comments! Yeah, I think the gunsmith is gunshy with AR's after having people hand him blown up ones, and I bet he didn't get the real story of how they blew it up. "Oh yeah, I did a ladder test just like you told me too"...
I think the bolt handle backup is his logic on that, but at this point I'm with you. My trajectory and range and velocity is fine at 2700-2800, and no need to take the bca bolt action weight penalty for 223.
Anyone looking for a new bca bolt action upper with bcg? Lol
-$170 shipped