Ultralight Ultralight Rifles

[Piker73]

The bolt handle bolts to the bolt carrier via two screws. I think the extra eight to nine ounces might be worth the trade of to you larger cases, like those based off the 220 Russian.

 

[KyleR1985]

The bolt handle bolts to the bolt carrier via two screws. I think the extra eight to nine ounces might be worth the trade of to you larger cases, like those based off the 220 Russian.

Anything inside of the upper receiver specific to that BCG? Or could you swap it into any upper?

I know openings to outside may need to be modified.

What about barrel extension? Standard?

 

[Piker73]

In the post with the pictures, there is one showing the difference of the internals off the BCA to the solo 300. There is more material removed from the one side internally of the BCA. This allows the bolt carrier to rotate in the upper. The BCA upper uses standard ar-15 bolt and barrels/extensions.

 

[packgoatguy]

Here pictures of the BCA 23 degree bolt throw. There are the weights and some comparisons to the gen 2 solo upper.

Thanks for taking the time to get these pics! Great resource!

 

[ACHILLES]

I’ve been slowly putting together my ul ul gasser and have run into a problem. Have a Tna poly lower. DSA low mass aluminum bcg. Nfa Lpk, but kept my psa trigger.

Seems like the bottom of the bcg is dragging on the hammer. I can pull the bolt back and it hangs on the hammer and holds the bcg in place. I have to hit the gun with the palm of my hand for it to release. Anybody know how to remedy this? Im definitely not an AR expert so it might be something simple.

 

[4090Sharps]

Any reason material can’t be chopped off the back of that BCA bolt carrier?

 

[Piker73]

Any reason material can’t be chopped off the back of that BCA bolt carrier?

I don’t see why the wings could not be chopped off. Currently BCA does not sell the upper only. But I am sure they will at some point.

 

[4090Sharps]

I don’t see why the wings could not be chopped off. Currently BCA does not sell the upper only. But I am sure they will at some point.

Thanks!

If Sig makes me sad for another year and denies me a miniature Cross, I might have to try one of these out…. It would be sweet to have one in 6 ARC if it extracts smoothly.

 

[Thegman]

Any reason material can’t be chopped off the back of that BCA bolt carrier?

Probably not, but the right wing will probably help seal the channel cut into the upper.

The track in the bolt carrier for the cam pin is going to allow some carrier movement before extraction starts. A quick pull is going to help with breaking the case loose.

The bolt handle is going to provide much more leverage to turn the bolt to the unlocked position.

This is what I was picturing when trying to figure out how it would work.

The one part I'm not sure about is the 23 degree throw. I thought AR bolts rotate 15 degrees. I was thinking 23 degrees would be bringing the bolt lugs back out of alignment with the barrel extension. Thought there would be 8 degrees of turn before hitting the cam pin, but it doesn't appear to be. ??

To add: I guess since there is 45 degrees between each lug, 22.5 (23) degrees would bring it right behind the extension lugs. I thought it was 15 degrees of rotation, but maybe not...

 

[Thegman]

I’ve been slowly putting together my ul ul gasser and have run into a problem. Have a Tna poly lower. DSA low mass aluminum bcg. Nfa Lpk, but kept my psa trigger.

Seems like the bottom of the bcg is dragging on the hammer. I can pull the bolt back and it hangs on the hammer and holds the bcg in place. I have to hit the gun with the palm of my hand for it to release. Anybody know how to remedy this? Im definitely not an AR expert so it might be something simple.
View attachment 811991

The bottom of the carrier always drags on the hammer, so are you sure it's not your bolt catch stopping the carrier?

Edit: The picture didn't come up initially, but I see now what you're talking about. Could that be drags from not depressing the bolt release? I wouldn't think your hammer would have sharp edges that could dig into the aluminum like that...???

 

[Piker73]

Thanks!

If Sig makes me sad for another year and denies me a miniature Cross, I might have to try one of these out…. It would be sweet to have one in 6 ARC if it extracts smoothly.

I tested it out with 6.5 Grendel using 110 grain steel case. It extracted and fed just fine.

Probably not, but the right wing will probably help seal the channel cut into the upper.

The track in the bolt carrier for the cam pin is going to allow some carrier movement before extraction starts. A quick pull is going to help with breaking the case loose.

The bolt handle is going to provide much more leverage to turn the bolt to the unlocked position.

This is what I was picturing when trying to figure out how it would work.

The one part I'm not sure about is the 23 degree throw. I thought AR bolts rotate 15 degrees. I was thinking 23 degrees would be bringing the bolt lugs back out of alignment with the barrel extension. Thought there would be 8 degrees of turn before hitting the cam pin, but it doesn't appear to be.

 

[Piker73]

I have attached photos one from BCA, a side shot of the bolt closed, one showing the bolt it’s self open, and one closed. The bolt does not over turn though.

 

[ACHILLES]

The bottom of the carrier always drags on the hammer, so are you sure it's not your bolt catch stopping the carrier?

Edit: The picture didn't come up initially, but I see now what you're talking about. Could that be drags from not depressing the bolt release? I wouldn't think your hammer would have sharp edges that could dig into the aluminum like that...???

It might be the bolt catch. I had it depressed when trying to cycle the bolt but I guess I need to check and make sure it’s actually clearing. It seemed to do this in the other aluminum lower after I ran it for 40 shots but not nearly as bad as this Tna lower. Its digging in hard just trying to cycle the bolt by hand. Thanks for the help.

 

[Thegman]

I have attached photos one from BCA, a side shot of the bolt closed, one showing the bolt it’s self open, and one closed. The bolt does not over turn though.

Is the bolt carrier aluminum or steel in the BCA?

 

[Piker73]

Is the bolt carrier aluminum or steel in the BCA?

Steel

 

[Trackselk]

I finally got one mostly put together with a 3x9 leupold ultralight. Need to screw down the handgaurd but that's all that's left. Going to be just a hair over 4lbs with my scythe-ti on it.
Thank you to all of you for helping to make this happen! Beat my UL kimber 22 creed by about 1lb 4oz with the same exact scope.
-13.5" LOP and 10" handgaurd

 

[Thegman]

I finally got one mostly put together with a 3x9 leupold ultralight. Need to screw down the handgaurd but that's all that's left. Going to be just a hair over 4lbs with my scythe-ti on it.
Thank you to all of you for helping to make this happen! Beat my UL kimber 22 creed by about 1lb 4oz with the same exact scope.
-13.5" LOP and 10" handgaurd

Looks like the Little Big Gun's brother!

What does the bare rifle weigh? Looks to be sub-3lbs (?). I think it's pretty cool to see just over a year after starting, guys are almost routinely knocking out sub-3lb rifles. I hadn't really even thought of a sub-3lb rifle a year ago.

 

[KyleR1985]

Looks like the Little Big Gun's brother!

What does the bare rifle weigh? Looks to be sub-3lbs (?). I think it's pretty cool to see just over a year after starting, guys are almost routinely knocking out sub-3lb rifles. I hadn't really even thought of a sub-3lb rifle a year ago.

It’s crazy.

I have everything on hand, except the ARIC bcg, to build a 3.5lb bare gun gasser. Add 3 ounces to have a folding stock

I’m not sure I want it. But easy enough if I did.

 

[Hardly_Hangin]

It’s crazy.

I have everything on hand, except the ARIC bcg, to build a 3.5lb bare gun gasser. Add 3 ounces to have a folding stock

I’m not sure I want it. But easy enough if I did.

I wish i would have done whatever you did cause that's 2.8 pounds less than my gasser, despite all the research on parts. Oh well. Mine is sitting at 6.3 pounds with swfa ul 2-10x33 on aero mounts.

 

[Trackselk]

Looks like the Little Big Gun's brother!

What does the bare rifle weigh? Looks to be sub-3lbs (?). I think it's pretty cool to see just over a year after starting, guys are almost routinely knocking out sub-3lb rifles. I hadn't really even thought of a sub-3lb rifle a year ago.

Yeah, I pretty much stole your design, thanks! It's 2lb 12.2oz with the 3 round 0.6oz magnetospeed mag. Add 0.7oz for the 4 round cut-down mag I made. I could drill holes all over and shave some more weight, but I'm not sure I want it any lighter...