Help upgrading my Bushmaster

[DeltaReact]

Howdy Y'all, 
so I have been scouring the internet trying to find info and I finally landed here so I thought id just ask.

I just received this rifle from my family, its one of the first rifles we ever purchased and I'm trying to change out the handguard but I know there are two styles of rifle DPMS and Armalite. I'm not quite sure which type I have. I know I'll have to change out the gas block but is there a big difference between adjustable and non-adjustable. I'm taking the gun up with me to Alaska this summer and its gonna take a beating. I'm looking for cheap and durable. recommendations would be helpful.

[colonelrhombus]

welcome.  that is an LR308.  an easy way to tell that it is DPMS is the rear of the upper receiver.  in this case, it's curved.  an armalite would be angled.

additionally, you have to determine if you have a high profile or low profile upper receiver.  it's hard to tell with the charging handle in, but it looks like a high profile.  

as far as changing out the gas block, you could probably leave the one you have and a free float rail would cover it.  depending on the rail, you may have to change out the barrel nut as well.  i have an adjustable gas block on one gun, but i dont think they're a necessity.  i own numerous AR patterned rifles and hand built each one from stripped uppers and lowers.  i've had no issues with the gas systems on any of them.  

[Armed Eye Doc]

Is it a new rifle?  Or is it an older rifle that is new to you?  Bushmaster used to be Rock River pattern 308s. 

Can you measure the interior depth of the buffer tube?  Please be as exact as possible.  That will provide needed information.  Rock River is not compatible with Armalite or DPMS pattern rifles.

[Sisco]

Like Doc says, early bushmasters were built for them by Rock River Arms  to their pattern. If it takes FN FAL magazines, it is one of those. Otherwise it is a DPMS standard pattern.

[DeltaReact]

It's an older rifle. we bought it used about 10 years ago. I currently don't have a way to measure it right now but I do have a steel mag which might be useful in determining. Also here's a better look at the upper.

Edited March 26, 2019 by DeltaReact

[98Z5V]

That's a DPMS mag.

[Armed Eye Doc]

42 minutes ago, 98Z5V said:

That's a DPMS mag.

 

52 minutes ago, DeltaReact said:

It's an older rifle. we bought it used about 10 years ago. I currently don't have a way to measure it right now but I do have a steel mag which might be useful in determining. Also here's a better look at the upper.

The question is answered.  I just didn't want you to buy something that didn't work.

[Cliff R]

You mentioned taking it to Alaska and it's going to "take a beating". 

For sure I'd install a free float rail system to you can install accessories, including a front sight. 

I take my 308-AR Elk hunting and although it's outfitted with a good scope and mount, I take along an A2 carry handle and matching front sight, just in case I accidentally amputate the scope on a rock during a hard fall. 

This actually happened to a member of our hunting party a few years ago.  We were at a "drop camp" for a week and early in the hunt he

fell and destroyed his scope.  His rifle wasn't equipped with back-up iron sights so it pretty much ruined a very expensive hunt for him.

Back then I carried a Marlin model 1895 in 45/70 with a 1-4 Leupold scope but left the iron sights on it.  These days I use my 308-AR and can remove the scope and install the sights in seconds.

You will also loose your sling swivel with most replacement set-ups, but with a rail system it's pretty easy to put one on it.  Below are pics of my 450 Bushmaster, with the ugly factory free float tube, then the replacement USA made free float hand guard I replaced it with.  There are a LOT of offerings out there, and most came with a new matching barrel nut.......Cliff