AR15 lower receiver, hole purpose?

[arakboss]

If you are going to make it a manual operated pistol, better to have the rotating bolt and not blow back. You can manually lock the bolt and have the lugs lock the bolt into the chamber and unlock by pulling the bcg back. So basically a rotating bolt straight pull like a steyr 95. You can cut the bcg in half like the sig vertex. Having a reciprocating bolt handle would be the guide to keep the bolt going straight back.

The gas key will keep the BCG upright and going straight back. The gas key will also keep the BCG from falling out of the upper.

 

[ronin223]

1. Just put clamp on gas block upside down to block gas port.

2. Keeping the bcg long so you can use the back part to close the bolt. Good idea, but ghetto.

 

[arakboss]

1. Just put clamp on gas block upside down to block gas port.

2. Keeping the bcg long so you can use the back part to close the bolt. Good idea, but ghetto.

The entire project is ghetto I am going to use a gas block for a temporary plug to test it out. Ultimately I would like to plug it in a way that would allow removal of the barrel nut with out having to remove whatever plug I use. At the same time I don't want to permanently plug it in case I want to run the barrel on a semi-auto set up.

 

[arrowshooter]

You can tap one of those 4-40 set crews in the gas port, then if you switch back put an adj gas block on there to compensate. One issue with this is the gas will burn out the threads and you'll need to go up a couple to close it back off. For the trouble, I'd just weld it up and buy another barrel to switch back. Easy Peasy.

 

[arakboss]

You can tap one of those 4-40 set crews in the gas port, then if you switch back put an adj gas block on there to compensate. One issue with this is the gas will burn out the threads and you'll need to go up a couple to close it back off. For the trouble, I'd just weld it up and buy another barrel to switch back. Easy Peasy.

I would worry that 4-40 screw would become a projectile one day. Welding over the set screw would cure that potential issue but of course that would be pretty permanent. I might just stick with gas block to plug holes and remove it along with barrel nut each time I swap barrels.

Here is the pistol with 300BO barrel and picatinny rail gas block mounted upside and with bipod mounted for display.

 

[arakboss]

I will need a similiar gas block in .875 size for 350 Legend barrel if I want to run the bipod on the gas block like I did on the 300BO barrel.

 

[arrowshooter]

That's pretty sweet!

 

[arakboss]

That's pretty sweet!

It should be fun shooting the 450 Bushmaster barrel free hand with standard two hand pistol grip. The 450BM upper will be a right side charging set up. I will have to use my right hand side charging upper for 7.62x39, 6.5 Grendel, 6.8 SPC and all the other AR15 compatible cartridges that don't use the 5.56 bolt size.

If this handgun performs well and is fun to shoot, I have an extra AR10 lower to try this with. That one will have to use my right hand side charging upper. I don't think BCA makes the left hand side charging uppers for the 308 platform.

 

[arrowshooter]

Man you got my brain spinning again , I'll explain. Back in the days when CA first started talking about banning AR's, I formulated a plan to switch over to all Gibbz uppers, plug the gas port and instant single action bolt gun. I do have everything changed over to the Gibbz, but these will not accommodate a bufferless system. I would not be afraid to butcher a $60 bolt, cut up a buffer spring until I got enough to strip a round out of the mag, and pickup one of the CMMG plugs that fill in the buffer extension hole in the rear of the lower. I must have way too much free time lol.

 

[arakboss]

Man you got my brain spinning again , I'll explain. Back in the days when CA first started talking about banning AR's, I formulated a plan to switch over to all Gibbz uppers, plug the gas port and instant single action bolt gun. I do have everything changed over to the Gibbz, but these will not accommodate a bufferless system. I would not be afraid to butcher a $60 bolt, cut up a buffer spring until I got enough to strip a round out of the mag, and pickup one of the CMMG plugs that fill in the buffer extension hole in the rear of the lower. I must have way too much free time lol.

The AR platform is such a great platform to experiment with. I wonder if Stoner ever imagined all of the configurations, cartidges, accessories, etc that people would be using in the AR platforms. I am going to try the manual loading configuration in rifles too.

 

[titsonritz]

What purposes does unthreaded hold sitting below the ext tube hole and next to the detent hole serve? Can it be drilled deeper without impairing the function of the lower receiver?

View attachment 1123570

Keeps the plate aligned.

So your A2 stock doesn't rotate on you

Both.

Note the mating tab on the receiver end plate, the A2 along with A1 stocks and Magpul MOE rifle stock. Drilling the hole out would remove the buffer retainer pin hole.

 

[P7M13]

It's for choads who don't know how to use an AR properly.