View Full Version : Carbon or SS better for full auto????
10-03-2010, 01:07 PM
In lieu of a chrome lined bbl would stainless or carbon be better in reguards to heat and barrel life in FA? (Subsonic .300 Whisper AR-15)
10-03-2010, 03:32 PM
I think it is mostly abrasion resistance that you would want, what with throat erosion and all.
If you're planning on burning barrels just go with whatever's cheap and replace it when you wreck it. Or hell, just don't get it too hot and it'll last plenty long.
10-03-2010, 05:50 PM
;606824'] Or hell, just don't get it too hot and it'll last plenty long.
So how do I know how hot is too hot?
10-03-2010, 06:04 PM
I've read that SS barrels have a longer barrel life in full auto than chromemoly, but the stainless barrels retain the heat longer also. the only barrel I've shot enought o notice a marked loss in accuracy though was a ss 223. I'd go with  and just get whatever barrel is cheaper as compared to the ammo/$ needed to burn it out the barrel will be cheaper.
10-03-2010, 09:07 PM
Well I quess my 1st question creates another question. Wouldnt you think heat would build up ALOT slower shooting subsonics say 9.0gr behind 220-240mk or whatever
10-04-2010, 12:29 AM
Heat doesn't come from the barrel. It comes from the burning powder, which doesn't vary according to steel type. One barrel steel doesn't "reflect" heat better than another (within practical limits).
Are you talking a mag dump or two? Or, red-hot continuous fire? Mag dumps, machts nicht. Red-hot, better start thinking water jackets. Anything in-between is a crapshoot depending on the round. The type of barrel steel is waaaaay down on the list of what you need.
10-17-2010, 11:19 AM
chrome moly with chrome lining if you can get it. the DOD experimented with stainless barrels in various full automatic rifle fire drills a decade or two back. i don't think they went very well.
my advice would be to call or email LMT and ask them as i know they destructive tested some stainless barrels and can give the straight scoop. rather than to go with the internet rumor mill--lol
you might try steve over at ADCO too.
the 300w is very quite but considering how hard brass is to get you might be ahead of the game to consider a canned firearm in 7.62x39 or some other more common round.
most AKs have chrome lining in the barrels and 1-10" twist rate supposed good up to 220gr.
AR-15s are getting pretty well developed in 7.62x39 today. chrome lined 1-10" twist barrels are around for them as well.
and your semi exotic 6.5 and 6.8spc would be adapted pretty easy to a can. though you might find yourself shot of brass for them later down the line. then you have a bunch of sub-sonic pistol cals--
you want the chrome in the canned barrel to help lube the bullet, that short powder charge ain't got the push you would have normally to get the slug out of the barrel. pounding a stuck round out of a barrel ain't no fun. and in a full auto a stuck bullet can be a disaster.
i would think shorter is better as well.
10-17-2010, 01:39 PM
I have got a guy making me a 7in bbl w/a 1:8 twist. I dont know of anyone that makes chrome lined whisper bbls, I wish I did.
10-18-2010, 12:50 AM
SS is GREAT! But it does not translate that greatness into a good material for an FA barrel. Once you get into the 800F heat range, the nickel content starts to lose it's "cool" properties. This translates into increased wear and / or deformation of the rifling lands.
How in gods name would I know this????? Well, back in the early 1990's, when i was unmarried, with no children, and owned three businesses that were all making a lot of money; I employed a fine gentleman named Charles Arthur, MSgt, USMC Ret. I had the concept of building rifles, and coming up with new concepts, and just having a shitpot full of fun doing it. We went through 26 variations of SS for a Class 3 design before abandoning the concept of using SS for the barrel. Bottom line; Carbon Steel, Chromed barrel gets you between 25-55K rounds. SS gets you 15K. Chrome and SS don't mix. At least, we never got it to work despite the efforts of some really smart metallurgy guys from Boeing and Northrop.
SS as a Semi or Bolt gun barrel works fine. You rarely if ever get those configs up to 800 F.
Just to be clear, I was the money and "vision" guy. I am simply repeating the reports given to me by my employees and contractors. If you have really technical questions, sorry. I can't answer them.
And all of this sucks because my intent was to produce 100% US made, SS AK rifles for the US market....Using "milled" receivers. Think Mini-14 and you will be close.
12-01-2010, 12:50 PM
I don't think with a 300 wisper subsonic you'll be getting your barrel that hot even with several mag dumps..it's not a belt fed.. I say you'll spend more money on the ammo than the price of a new barrel.. I just get chrome molly barrel and have fun.. Stainless steel will last longer in the throat in a slow fire mode.. i.e. not geting it too hot. Chrome molly is cheaper.. B2B