Magpul UBR on Bushmaster 450 Carbine

[SoulHunter]

Glad that I found this forum! I am trying to install a Magpul UBR stock on my Bushmaster 450 Carbine, and I need to purchase a carbine buffer and spring to work with the new stock. From a preliminary search on this board, I see that there are many options regarding spring tension and buffer weights--what spring and buffer should I use with the UBR stock? Thank you in advance for your help--I was just unsure enough about what to get that I thought I better ask.

[gadgetguy1288]

I'm not gonna be much help as my upper hasn't arrived yet, but I have my lower all built finally and am also using a UBR. Right now it has a standard carbine spring and Spikes Tactical ST-T2 buffer. And everything Ive read has said stay as close to a standard rifle buffer as you can because that is what its made to work with.

[SoulHunter]

Right now it has a standard carbine spring and Spikes Tactical ST-T2 buffer

Thanks for the reply. I was thinking about using the ST-T2 buffer with a Tubbs CS Flat Wire Spring, but I wasn't sure whether I needed to use the AR-15 version or the AR-10 version (it seams that they only make 2 springs, both of which work in either a rifle or carbine length tube). I was also wondering if their carrier weight system would be helpful in my setup.

[Siringo]

I use the Tubb's flat spring and it works great. I think it is smoother and you can use the same spring in the carbine or rifle buffer tube. Currently, I am running it in a rifle tube and also the the carrier weight system. I use the heaviest setup. I did this because I wanted to slow down the action and minize bullet jump in the case. Cycles just fine with factory ammo. Whatever system you use, try to stay around the 5 oz weight for the buffer -- that is what is in the rifle.

[SoulHunter]

I use the Tubb's flat spring and it works great. I think it is smoother and you can use the same spring in the carbine or rifle buffer tube. Currently, I am running it in a rifle tube and also the the carrier weight system. I use the heaviest setup. I did this because I wanted to slow down the action and minize bullet jump in the case. Cycles just fine with factory ammo. Whatever system you use, try to stay around the 5 oz weight for the buffer -- that is what is in the rifle.

Siringo, thank you for the feedback. Quick question about your setup--did you use the AR-10 spring or the AR-15 version from Tubb's? Also, if I installed the Tubb's flat spring and a heavy buffer, what advantage would the carrier weight system offer over the heavy buffer & spring alone? FWIW, I will be shooting factory loads almost exclusively.

On a separate note, I did install the Timney drop in trigger--very nice!

[MudBug]

I'm running a 9mm buffer in mine mostly because I'm running a Cavalry Arms lower and the heavy buffer reduces the pounding from the recoil.

[Siringo]

I use the Tubb's flat spring and it works great. I think it is smoother and you can use the same spring in the carbine or rifle buffer tube. Currently, I am running it in a rifle tube and also the the carrier weight system. I use the heaviest setup. I did this because I wanted to slow down the action and minize bullet jump in the case. Cycles just fine with factory ammo. Whatever system you use, try to stay around the 5 oz weight for the buffer -- that is what is in the rifle.

Siringo, thank you for the feedback. Quick question about your setup--did you use the AR-10 spring or the AR-15 version from Tubb's? Also, if I installed the Tubb's flat spring and a heavy buffer, what advantage would the carrier weight system offer over the heavy buffer & spring alone? FWIW, I will be shooting factory loads almost exclusively.

On a separate note, I did install the Timney drop in trigger--very nice!

The only reason I went to the extra weight (CWS) is I was experimenting with heavy bullets (400's). Otherwise, the 450 will run with stock GI Rifle Parts. I used the AR15 spring and actually purchased it because I can switch back and forth from a carbine buffer tube or a rifle buffer tube and not have to use two different springs. As long as you are shooting only factory and as Wildcatter said about me not "putting your hair on fire" -- you'll be fine.

[Hoot]

Before you plop down your hard-earned $58.00 + S/H for that CWS, consider fabricating one yourself. It isn't hard to turn down 5/8" steel rod stock to .616" though you might want more than a .009" lip. I suppose you could use 3/4" rod stock just as easy. If you don't have a little hobby lathe, you probably know someone who does. Food for thought.
Hoot

[Siringo]

The only negative with the CWS is the flange. It is not possible to pull the rear action pin and tip open. To clean/disassemble, it is necessary to remove both the front and rear pins. Not a big deal -- . Some are having the back of the bolt carries relieved to accept the flange so the action will tip open.

Another option -- if you want the heavy buffers -- go to "www.heavybuffers.com"

[BayouBob]

Anybody tried a hydraulic buffer?