450Bushmaster.net

OK guys , the more I look into this the more I think I'm getting confused. I had some problems with my 5.56 today and looking into the problem found that my .450 may be wrong too. I have a 20" rifle 450 , with a standard mil-spec collapsible carbine stock. Standard carbine buffer. Is this not good? Shall I get a rifle stock with a rifle buffer / tube? It functions fine but the book I have says not to mix carbine buffers / tubes with rifle buffers / tubes?

What kind of problems did you have? The most common problem you read about in AR forums (I've experienced this myself) is checking to make sure gas key is staked tight to the bolt carrier. As far as the buffer, Bushmaster designed it to be drop in using factory buffers. I use my factory Bushmaster carbine stock and buffer and it works great. Some people say use the heavier M4 buffer or other buffers, but that seems mainly for recoil control. You can not mix carbine buffers with rifle buffer tubes or rifle buffers with carbine buffer tubes. The rifle tube and buffer are longer, if you put a rifle buffer in the carbine buffer tube the bolt carrier would not be able to travel far enough to operate. If a carbine buffer was put in a rifle tube, I can only imagine that the tension would be too light and would not chamber and lock.

The .450 works fine. Yes a rifle buffer is just to long for a carbine tube , it would not operate. My 20" 5.56 has a carbine tube and buffer. The problem is the trigger does not reset. BUT I noticed ( after I got home) the disconector spring was not seated properly , possibly causing a bind with the hammer. I was doing some research ( in my book that I half read ) and the author states that "a carbine buffer and tube on a rifle gas system can sheer off the gas key or crack the lower ". I was just wondering does this apply to the .450 also? Doesent the bore diameter change port pressures ?

No problems here with an M4 buffer in a mil-spec buffer tube.

The 450 Bushmaster is built around the rifle buffer tube and buffer that weights about 5.3 oz. Over my tenure of working with this platform, I have gone to a carbine stock (and buffer tube). I HAD used a buffer that weighed 2.8 oz and that did cause some problems while working with heavy slow bullets. Action was opening to soon.

I currently run the carbine system with an H3 buffer. In addition to that, I have a Tubbs Carrier Weight System installed in the bolt. Reason for the additional weight was to slow the action down on opening and chambering (to help minimize bullet jump). If you are using factory or equivalent reloads -- this is not necessary though.

As long as you use a buffer that weights close to the factory weight or heavier -- you will not have problems. Do not use the rifle buffer in a carbine tube -- the buffer is to long. Do not use a carbine buffer in a rifle tube -- it is to short and may cause damage to the upper receiver if fired. Just keep the buffers matched to the correct tube and you'll be fine. Also, there are rifle actions springs and carbine action spring --rifle is longer than the carbine. Use the correct spring per tube.

The 450 Bushmaster platform is built around the standard AR GI parts.

For buffer info go to: "www.heavybuffers.com".

Thanks for the replys. I fixed it last night but could not test until today. I was just sweating it until then.It was the disconnector sping. Just one of those things I should have paid more attention to when assembling. The rifle functioned flawless. Three inch groups at 100 with irons is acceptable for me for a battle rifle and ball ammo.

I use a Magpul MOE stock with a carbine length Enidine hydraulic buffer. So far, no problems.

bighole wrote:OK guys , the more I look into this the more I think I'm getting confused. I had some problems with my 5.56 today and looking into the problem found that my .450 may be wrong too. I have a 20" rifle 450 , with a standard mil-spec collapsible carbine stock. Standard carbine buffer. Is this not good? Shall I get a rifle stock with a rifle buffer / tube? It functions fine but the book I have says not to mix carbine buffers / tubes with rifle buffers / tubes?

I found that the A2 stock with the 308 buffer and 308 spring work great. I have a 50 B,450b,6.5g, 6.8R and use that set-up on all of them. Bolt lock-up time is increased and the recoil is reduced. The MOA on all of them was reduced. i have never had a feed problem or a breakage. I have 2 5.56 rifles , a 20" bull and an 18" of which I use the 5.56 buffer and spring. I just keep things simple.

wackoo450 wrote:I found that the A2 stock with the 308 buffer and 308 spring work great. I have a 50 B,450b,6.5g, 6.8R and use that set-up on all of them. Bolt lock-up time is increased and the recoil is reduced. The MOA on all of them was reduced. i have never had a feed problem or a breakage. I have 2 5.56 rifles , a 20" bull and an 18" of which I use the 5.56 buffer and spring. I just keep things simple.

Like the ones DPMS uses on their LR308 rifle? I never thought to try that. My LR-308 AP4 uses a standard ar15 collapsible tube but with a heaver spring and buffer. I'll have to swap it over to my .450 to see if it still works. Great Idea, and welcome aboard(even though you have been lurking around since April)!

2zero6 wrote:

wackoo450 wrote:I found that the A2 stock with the 308 buffer and 308 spring work great. I have a 50 B,450b,6.5g, 6.8R and use that set-up on all of them. Bolt lock-up time is increased and the recoil is reduced. The MOA on all of them was reduced. i have never had a feed problem or a breakage. I have 2 5.56 rifles , a 20" bull and an 18" of which I use the 5.56 buffer and spring. I just keep things simple.

Like the ones DPMS uses on their LR308 rifle? I never thought to try that. My LR-308 AP4 uses a standard ar15 collapsible tube but with a heaver spring and buffer. I'll have to swap it over to my .450 to see if it still works. Great Idea, and welcome aboard(even though you have been lurking around since April)!

I use the DPMS LR 308 A2 stock,spring, and buffer. I make one order and get it as a package. keeping it simple. I like to
"lurk" on the threads,,a lot of info here. I load 57 calibers and for 51 years at the bench. I am a HOOT fan.
I like that 40 carbine thread,,I think i will get a LR308 upper,bolt and barrel, get it rechamberd and bored, 1 in 10 twist,
stretch the neck of the 308 case, with a 40 s@w resizer ball. that is keeping it simple. I make 357 Herret from 30-30 cases, so the 40 carbine should be pretty easy. Let me know how the LR308 AP$ works on the 450b.