New Member, short barrel questions!

[longwaytofall]

Hello everybody!
I love the site! I am pleased to say that I ordered a cav arms lower receiver a couple days ago, and plan on putting a 450 bushmaster on top of it! This will be my first AR build, so if I sound ignorant to AR stuff, I am!! Haha.

My main goal for the build is to make it as lightweight as possible, within reason. I would like to do this in a couple ways:

1. Shorten a 16" barrer down to, or buy, a 11.5" or so barrel and permanently afix a muzzle brake of some type (possibly hand built for light weight). I also thought about using a lathe to reduce the barrel's contour, but unless I had very good info confirming that it was safe to do so, I don't think it is worth the risk.

2. Use a light weight, possibly composite, probably smooth side (no forward assist) upper receiver (I have access to a mill to enlarge the ejection port. Has anybody opened up the port on a composite upper? I am hoping the non-metal material won't be a problem).

3. Carbon fiber front guard, of some sort. I'll also try to keep the gas block simple.

That is about it! I am hoping these will make a large difference in weight. I'll do my best to equip the rifle with a muzzle brake that will take care of as much of the recoil as possible, as the light weight will obviously increase it.

I am open to any and all suggestions regarding what I can do to acomplish this project, I need all the help I can get!

Something that I have not found much information on, specifically, is:
What will the reduction in barrel length do to the gas system operation? I would imagine it will not be getting as much gas, and I might have to make some changes to compensate for this.
What do I have for options for buying a barrel and bolt/carrier group? I would be willing to buy a complete 16" upper and change out the parts I want to, but if I am going to be changing just about everything then it might be better to build the upper from the ground up, buying the components seperately.

A helpful guy on CalGuns turned me onto some great info regarding the 450b, including a link to some very cheap ammo (well, certainly not "cheap" but compared to all the other prices I have been seeing... haha), so I went ahead and bought 200 rounds before the deal ends.
I guess I am committed now!!!

Thanks to everyone for your time, and I look forward to hearing from you!

Micah

[mnhornet]

Welcome to the board.
I don't think you'll get much weight savings by cutting 5" off the barrel, and adding a 5" muzzle device. The 16" is pretty thin walled already. A carbon freefloat tube will offer more weight savings than the other options.

[longwaytofall]

Hi,
Thanks for the reply. Also, thank you to the moderator who approved my post!

Ok, I will certainly have to think about keeping it full length. It would also be a benefit due to being able to keep the barrel threaded, and not welded. What is the diameter of the barrel, forward of the gas block? I think I read that it was around 1 inch, which seemed to be quite heavy to me. If I find out for sure, I can do some math to figure out the weight savings. Besides just the weight, I think it would help with the balance, bringing the center of gravity towards the rear.

Does anybody else have any tips for my project?? Specifically, I am worried that if I DO cut the barrel, I might have to make some changes to the gas system... Is this a possibility?

Thanks everybody!

[commander faschisto]

I think you'd best stick with the 16" barrel as designed. There are a host of problems to be solved when you change lengths, especially with a cartridge like the 450b. Just ask wildcatter about that! If you went with a carbon-fiber lower, 6-position stock, and carbon-fiber handguard on the 16" barrel, I think that would be about as light as the 450b is going to get. Keep in mind that with lower weight comes more recoil impulse. You could wind up with one that "kills on one end and wounds on the other"...

[Clipity]

Welcome

Calguns is a great site but for info on the 450b you have found the place. I hope you bought your ammo from here http://palmettostatearmory.com/450-bushmaster.php as they have the best price I could find on the net and at 200 rounds with the $12 shipping is just over $21 a box.

[longwaytofall]

Yeah, the more I think about it, the more I think that 16" is the smart move. Even with a regular 16" upper from bushmaster, on the Cav Arms lower I will be using, will be right about 7.5 lbs. That isn't bad. As you said, I think there is some good weight to be saved with the foreguard, so maybe I can get below 7. I am used to an FAL, which is pretty heavy!!

About the ammo, yes Palmetto is where I ordered it

I don't know if I mentioned it earlier, but if anybody decides to build a very short rifle (or pistol) there is a 450 bushmaster barrel on gunbroker right now, with a very low starting bid. 10.5 inch length, and pistol length gas system.

[KY_Mike]

I went lightweight with my current .450 and without doing anything extra special, it's right at 6.60 lbs currently. That's with standard 16" barrel, free float tube, upper... basically the compete Bushmaster upper as it comes with the gas block swapped out for a Yankee Hill flip up sight/gas block and GG&G flip up rear sight. Lower is a standard Aero Precision lower with plain ol' 6 position carbine stock & H buffer.

I might get into removing unnecessary metal in the handguard & upper down the road, but not likely. It's plenty packable as is.

[BillytheKid]

Franklin Armory has finally come out with the XO-26 Pistol in .450 Bushmaster caliber.

It has a barrel length of 11.5" and an overall length of 26" not including the muzzle break.

Bill

[commander faschisto]

Cool...more hardware choices, the better, for the caliber! Better start doing your forearm and hand muscle-building exercises...

[Colohunter]

Franklin Armory has finally come out with the XO-26 Pistol in .450 Bushmaster caliber.

It has a barrel length of 11.5" and an overall length of 26" not including the muzzle break.

Bill

So if you live in a state that is SBR friendly, you could buy the pistol, then when you get your stamp in, just put a stock on it and you have your 450 SBR.