Ultralight Ultralight Rifles

[Trackselk]

You should literally just get the 223/5.56 case, run it through the 6x45 die and done. the expander ball will take the neck from 224 to 243...... with brass cases.

For sure, but I've been rambling on about the fancy new nickel cases since there seems to be a demand for more power and they don't expand like brass, so you could either run the 6x45 a lot faster, or the same goes for 300 blk. 80k psi IIRC
Not sure if the new federal cases are of any use but: "The 7mm Backcountry is based on a .280 Remington and 30-06 case". These also handle 80k psi.

Edit: just info I'm passing along, I'm sticking with 223/5.56 with these new cases

Edit: I'm sure the 7mm BC have way too big of a case head for AR's, but maybe useful info for some other project.

 

[KyleR1985]

If someone sends me fancy .223 magic cases, I’ll chance ruining my 6x45 sizing die to neck some up.

 

[Trackselk]

If someone sends me fancy .223 magic cases, I’ll chance ruining my 6x45 sizing die to neck some up.

I'll donate a couple to help you poor chaps that can't hunting with 223, or those that just want more lead. They might be slightly inferior as they'll probably have a slight factory crimp. I bought a box of 50 loaded from fantom and I'm just going to pull the bullets and powder, as I had no need for the 500 or 1000 quantity that shell shock is selling. They're actually not expensive at all per round, but 50, or 48 will last me a long time if I get the predicted 3 loadings out of them anyhow.

 

[packgoatguy]

I didn't think so. So what applies pressure to the bcg to keep it forward?

Someone else with a better grasp of AR15 mechanics should probably field this one... but the short answer is the spring is not used to keep the bolt in battery, it's function is to return the bolt to battery in a semi-auto gas operated version. The teeth on the forward end of the bolt rotate into/behind corresponding teeth in the barrel extension. Those teeth locked together hold the bolt in battery.

 

[HighUintas]

I think it's possible you'd collapse a shoulder necking up unless you use one of those long taper carbide mandrels. But who knows! It may also spring back too much to be able to seat a bullet

 

[Trackselk]

I think it's possible you'd collapse a shoulder necking up unless you use one of those long taper carbide mandrels. But who knows! It may also spring back too much to be able to seat a bullet

I was wondering about that, I'm thinking step up to 6, and then 6.5 to land back at 6, lots of lube. Better yet, k&m would probably make you a 6.25, or whatever it needs to be to land at 6 if 6.5 is too much. If my 6.5 mandrel doesn't sell (ebay) before I get the "brass", then I could give it a go, but, I don't have any 6mm projectiles to test the fit. I'll probably just mail them to one of you all

 

[Thegman]

I didn't think so. So what applies pressure to the bcg to keep it forward?

The Solo uses what I call "detent key" in place of the gas key. It's a spring loaded ball bearing that interfaces with the upper receiver when the bolt goes in battery. Without that, yes it could fall open more easily.

@StupidLightweight has built a couple before solo probably even existed. With a round in the chamber, friction on the bolt interface kept (keeps) his in battery pretty well.

 

[Thegman]

For sure, but I've been rambling on about the fancy new nickel cases since there seems to be a demand for more power and they don't expand like brass, so you could either run the 6x45 a lot faster, or the same goes for 300 blk. 80k psi IIRC
Not sure if the new federal cases are of any use but: "The 7mm Backcountry is based on a .280 Remington and 30-06 case". These also handle 80k psi.

Edit: just info I'm passing along, I'm sticking with 223/5.56 with these new cases

Edit: I'm sure the 7mm BC have way too big of a case head for AR's, but maybe useful info for some other project.

I seem to be able to push 77TMK/73ELD-M fast enough out of a 16 barrel to work very well out as far as I generally shoot at game. What would interest me more is pushing something like a 62 grain Maker copper bullet, really fast, like say 3,200 fps. ???

 

[Trackselk]

I seem to be able to push 77TMK/73ELD-M fast enough out of a 16 barrel to work very well out as far as I generally shoot at game. What would interest me more is pushing something like a 62 grain Maker copper bullet, really fast, like say 3,200 fps. ???

At 75-80k psi I think that's in the cards. I'll let you know how fast I get these 62gr DRT'S in a 16". Might take me a month though

 

[FredBear86]

Someone else with a better grasp of AR15 mechanics should probably field this one... but the short answer is the spring is not used to keep the bolt in battery, it's function is to return the bolt to battery in a semi-auto gas operated version. The teeth on the forward end of the bolt rotate into/behind corresponding teeth in the barrel extension. Those teeth locked together hold the bolt in battery.

Gotcha. Makes sense. If that is the case could the back half of the bcg be cut off so the charging distance isn't as long and can save weight?

 

[Trackselk]

Gotcha. Makes sense. If that is the case could the back half of the bcg be cut off so the charging distance isn't as long and can save weight?

Yup, I think the SOLO bcg has that treatment

 

[Thegman]

And, lightweight rifles seem to shoot okay, too.

I was second guessing how well I could shoot out of my blind, which is me half-kneeling on the ground and resting the handguard on a little branch stub. Never seemed terribly solid.

Shots were at about 110 yards. The 3 marked shots were 88ELDs (the upper hit was the last which had set way back in the case - so that's half an excuse for that shot).

Adjusted the scope to where it should have been pretty close for the 73ELD-M and sent three of those. I don't know if I’d do a whole lot better with a rifle that weighs 3x as much (?).

Now if I could just start shooting like Taudisio...

 

[Thegman]

Gotcha. Makes sense. If that is the case could the back half of the bcg be cut off so the charging distance isn't as long and can save weight?

Yes, that's exactly how the solo is made. Nothing protrudes back into the stock, so any stock, or even no stock will function fine.

 

[FredBear86]

Thanks guys. Hated to derail your thread, more of an archery guy than gun, but that stupid light ar packgoatguy built has me intrigued. Thanks for all the help. I'll continue my research

 

[packgoatguy]

Gotcha. Makes sense. If that is the case could the back half of the bcg be cut off so the charging distance isn't as long and can save weight?

That is in fact exactly what is done. If you look closely at a Solo300 bolt, you will note that it is identical in all respects to any other Ar15 bolt carrier group... just missing the unnecessary back half.

 

[Choot]

Thinking about this, it's a good idea to keep your cam pin greased as well, especially the interface between the cam pin shaft and the bolt carrier. That area adds friction when unlocking and the aluminum bolt carrier of the Solo, aluminum being softer, might be a little "stickier" against the cam pin than a typical steel carrier would be.

That’d a good thought. I will pull it apart and clean/grease it up and hopefully shoot it this weekend and see how it does

 

[Matthausarchery]

Had anyone had any issues with the TNArms15 carbon lower? The weight savings is great but I could probably live with the extra 4oz if it has any repeated failure points.

 

[KyleR1985]

Had anyone had any issues with the TNArms15 carbon lower? The weight savings is great but I could probably live with the extra 4oz if it has any repeated failure points.

Don’t fire it without either the bolt catch, or a same thickness spacer installed in the space it goes inside the receiver.

It will crack the polymer. Mine cracked.

Installed bolt catch, functions fine, minus there being a bolt catch there annoying me at the range.

Just haven’t had time to make a spacer for the receivers I have.

 

[Thegman]

Don’t fire it without either the bolt catch, or a same thickness spacer installed in the space it goes inside the receiver.

It will crack the polymer. Mine cracked.

Installed bolt catch, functions fine, minus there being a bolt catch there annoying me at the range.

Just haven’t had time to make a spacer for the receivers I have.

Wasn't that cracking from dropping the hammer directly against the lower? That can jack up any AR lower, it's not specific to polymer.

As long as you have the upper with the bolt carrier in when you're dry firing, the TN Arms shouldn't be any more prone to cracking than any other receiver. With those parts installed, there's no stress on the frame there.

As far as issues with the TN Arms frame, other than -some- triggers not fitting without a little fitting work here or there (pretty easy to do on polymer), none that I can think of.

 

[KyleR1985]

Wasn't that cracking from dropping the hammer directly against the lower? That can jack up any AR lower, it's not specific to polymer.

As long as you have the upper with the bolt carrier in when you're dry firing, the TN Arms shouldn't be any more prone to cracking than any other receiver. With those parts installed, there's no stress on the frame there.

Correct. Sorry, should have been even clearer.

Short version - with nothing stopping a metal hammer dropping but the lower, and no bolt catch in place, or a filler material, you will crack the TNA lower at contact point. And may do the same to other Lowers.

Don’t be like me.