PDA

View Full Version : carbon fiber - possible to rebuild the upper? (looking for ultralight pack rifle)


steve_77
09-28-2009, 7:32 PM
Curious if its possible to have someone rebuild a CA legal bushmaster carbon fiber (both receivers carbon fiber) rifle to a different chambering - was leaning towards either the 6.5 grendel or the 6.5-45mm (aka SSK industries 6.5 MPC)

link with photo comparison:
http://www.sskindustries.com/6_5mpc.htm

http://www.sskindustries.com/6_5grendel.htm

(not trying to plug SSK)

the only reason im limiting to these is both appear to work good with 120gn bullets, both are smaller and will get complete ignition with a shorter say 16" barrel.

Im going for an ultra light 'pack' repeating rifle - some suggested the:


1) AR-15 (if i can find use carbon upper/lower)
2) keltec su-16 (like the way it folds up)
3) CZ-527 carbine
4) Ruger Model M77 MKII Compact Rifle
5) Remington Model 799
6) charles daly mini-mauser

basically looking for light and portable id like to go AR if i can build a very light gun...

What are the restrictions on a collapsible / folding stock? If i leave it a "top loader" and dont open-up the magwell - would it be legal to have a folding stock on it - so i can fit it into a backpack when hiking?

mds2004
09-28-2009, 8:22 PM
I know you said pack rifle, but if you want a light lower for an AR, go with Cavalry Arms. Ugly but lightest out there.

wash
09-28-2009, 8:41 PM
#1. Read the OLL flowchart and decide if you want a fixed magazine or a featureless build.

#2. Find someone that will make you a 16" carbine gas system pencil barrel in the chambering you want (this might be hard).

#3. Figure out how much extra weight an aluminum upper is (my guess is not much).

#4. Ace Ultralight entry stock is probably as compact and light as you can get for a stock.

E-120
09-28-2009, 9:02 PM
I have a Carbon 15 as well, but for a pack rifle I use a Keltec SU-16. Its light weight as uses my AR mags.

steve_77
09-29-2009, 8:46 AM
E-120,

what is the weight difference between carbon 15 and keltec, i've looked into keltec the only problem is finding someone to rebarrel it in a 6.5 caliber; thats why i was thinking a fixed mag ar build might be easier.


mds2004,

Will the Cavalry Arms carbon lower mate up to the bushmaster carbon upper receiver?
and is there something wrong with the bushmaster carbon upper receiver ?



was thinking of cav arms lower MKII w/ 10 round poly mag

or

CA legal bushmaster carbon 15 upper + lower w/ Ace Ultralight entry stock

Also nobody really answered my orig question - i think it can be done but a carbon 15 is in 223. caliber - can i use the same upper receiver in a 6.5Grendel (ie 7.62x39 bolt face) or is the upper receiver too small for that (ejection port etc)?

E-120
09-29-2009, 9:54 AM
I don't like carbon pieces chafing against non carbon. I try not to mix other uppers and lowers. Just my own feeling about dissimilar materials. The su 16 weighs around 4.3 pounds as I recall.

mds2004
09-29-2009, 11:07 AM
I dont see why the carbon upper would not eject the 6.5. I just did a rough measurement of my aluminum AR upper and it measures 3"x.5" and I also roughly measured my Bushmaster Carbon15 and it seems to run a tad longer than 3". I thought it was smaller too because the edges are more rounded but although they are more rounded the hole is also elongated. If someone was not borrowing my micrometer I would take actual measurements for you.

Id email Cavalry about using their lower + a carbon upper.

and FWIW, I am happy with my Carbon-15

mds2004
09-29-2009, 11:16 AM
Also, when comparing one lower assembly with:
Carbon lower, standard 6 pos. buttstock, Bushmaster 20rd mag body, hogue grip + LPK
versus
aluminum lower + MIAD grip + CTR buttstock + PMAG 20rd body + LPK

There is still a noticeable difference which could be considered substantial if it is a pack gun.

ar15barrels
09-29-2009, 11:44 AM
Curious if its possible to have someone rebuild a CA legal bushmaster carbon fiber (both receivers carbon fiber) rifle to a different chambering

The bushmaster branded carbon guns should accept standard barrels.
I don't know if bushmaster kept the barrel nut threads overisized like professional ordinance did or not.
I have had to open the threads on a freefloat handguard to be able to install it on a professional ordinance carbon fiber upper reciever.

mds2004
09-29-2009, 11:47 AM
The bushmaster branded carbon guns should accept standard barrels.
I don't know if bushmaster kept the barrel nut threads overisized like professional ordinance did or not.
I have had to open the threads on a freefloat handguard to be able to install it on a professional ordinance carbon fiber upper reciever.

Aren't Bushmaster Carbon-15s actually made by Professional Ordinance? At least this was the rumor I heard. I also read that POs carbons were not as good under their name though, but quality went up when it was under Bushmaster's name.

This is all internet here-say though.

wash
09-29-2009, 11:53 AM
Re-barreling a carbon upper is possibly opening a can of worms. With the price of aluminum uppers being fairly low, unless there is great weight savings, aluminum seems like the smart move to me.

It also lets you swap to .223 or sell off the other upper if you want.

CHS
09-29-2009, 12:07 PM
The bushmaster branded carbon guns should accept standard barrels.
I don't know if bushmaster kept the barrel nut threads overisized like professional ordinance did or not.


I just worked on one yesterday. The barrel nut threads are definitely oversized.

But apart from that, it should take a standard barrel and BCG, regardless of caliber.

In the case of the one yesterday, the guy wanted a Yankee Hill handguard. We just ended up selling him a new YHM M4 upper receiver and swapped the barrel and BCG over with the new handguard and gas block. It fit the lower just fine.

mds2004
09-29-2009, 12:13 PM
Also make sure the barrel is not cut for M4 ramps.

ar15barrels
09-29-2009, 12:19 PM
I just worked on one yesterday. The barrel nut threads are definitely oversized.

In the case of the one yesterday, the guy wanted a Yankee Hill handguard. We just ended up selling him a new YHM M4 upper receiver and swapped the barrel and BCG over with the new handguard and gas block. It fit the lower just fine.

I have opened up a YHM barrel nut to fit those oversized threads.
It was for a guy with a RAW.
The PO guns had a purposely mis-matched pin location so you can't just swap to an aluminum upper reciever.

When Bushmaster bought PO, they standardized pin locations, bolts and barrel extensions to normal AR parts.

ar15barrels
09-29-2009, 12:19 PM
Aren't Bushmaster Carbon-15s actually made by Professional Ordinance?

Bushmaster BOUGHT PO.

steve_77
09-29-2009, 12:44 PM
Wow - appreciate all the info -- so it can be done.. cool

So I suppose the most important questions are then:

1) what is the word of longevity/reliability of the bushmaster carbon 15 vs the cavalry arms MKII lowers

2) anyone know the weight difference between the two
( cavalry arms MKII lower & [bushmater carbon 15 w/ ace u-lite entry stock] )