# AR barrel question



## ben300win (Mar 4, 2009)

I have an AR with a bull barrel. All black. The barrel is stamped with SUM 5.56 just in front of the front sight. I was told by the seller that I bought it from that it was a Shillen Ultra Match Barrel. Is that what the markings mean?
Also, I would like to know if it is stainless that has been duracoated , or is it just a chrome moly barrel? It is .750 at the muzzle and I think I remeber that it is a 1-9 twist. I looked the twist up on Liljas website and found that the 69 grain bullet works best in it. Thanks for the help, Ben.


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## jglenn (Mar 4, 2009)

if memory serves

SUM stands for Stainless Ultra Match. They have a minimum size chamber with a slightly shorter neck-- I believe they were all chambered for 223 Remington Minimum SAAMI spec to aid in accuracy.

not intended for 5.56 military ammo also unless they have now done up a SUM barrel in 5.56 chambering??? Perhaps someone will jump in on that possibility ??

I believe Olympic arms has a write up about their barrel marking on their web site that covers the SUM barrels


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## Truegiant (Mar 4, 2009)

jglenn said:


> if memory serves
> 
> SUM stands for Stainless Ultra Match. They have a minimum size chamber with a slightly shorter neck-- I believe they were all chambered for 223 Remington Minimum SAAMI spec to aid in accuracy.
> 
> ...




Pretty much hit the nail on the head. That is the info I have been using for a while now. I recomment a 69gr .223 match ammo and happy shooting.


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## ben300win (Mar 5, 2009)

Thanks guys. I could not remeber what the SUM stood for. I have been shooting Wolf 55g SP in it without any problems, but I know that I can get better accuracy out of it. I just hate to pay for match ammo just for plinking.


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## rjcruiser (Mar 6, 2009)

ben300win said:


> Thanks guys. I could not remeber what the SUM stood for. I have been shooting Wolf 55g SP in it without any problems, but I know that I can get better accuracy out of it. I just hate to pay for match ammo just for plinking.



I've heard that bad things can happen from shooting wolf ammo out of ARs.  I think that it is too hot for the rifling.

Can anyone of the AR experts school me on this one?


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## bigboye (Mar 6, 2009)

rjcruiser said:


> I've heard that bad things can happen from shooting wolf ammo out of ARs.  I think that it is too hot for the rifling.
> 
> Can anyone of the AR experts school me on this one?




I shoot Wolf 69g and have never had an issue. The one thing that seems to happen to me is that more money remains in my account, but I would call it a bad thing. I do have brass for HD. I use the Wolf for basic plinking.


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## 4wheeling4life (Mar 6, 2009)

i have been shooting wolf through mine and i can not tell any difference than with american eagle. i have not laser temped the barrell to compare barrell or anything but just my .02


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## Wiskey_33 (Mar 6, 2009)

bigboye said:


> I shoot Wolf 69g and have never had an issue. The one thing that seems to happen to me is that more money remains in my account, but I would call it a bad thing. I do have brass for HD. I use the Wolf for basic plinking.



But you'll spend more time cleaning. That wolf is some dirty stuff.


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## ben300win (Mar 8, 2009)

Most of what I do with mine is plinking. I did buy some american eagle for it when we went prarie dog shooing. Gotta love an AR for prarie dogs.


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## Jason280 (Mar 8, 2009)

Yes, the SUM is an Oly Arms barrel, and they have a reputation for being very accurate.   You can definitely shoot 69-75gr ammo through the barrel, and possibly 77gr bullets as well.  Some 1/9 twist guns will shoot 77s without any problems, while others don't seem to stabilize as well.  


> I've heard that bad things can happen from shooting wolf ammo out of ARs. I think that it is too hot for the rifling.



Wolf, at least the older stuff, is some of the slowest 5.56/.223 ammo you can by.  Most of the stuff I have chrono'd has been around 200fps slower than comparable ammo, so you won't have any problems with it.  It is a little dirtier, but that is a non issue if you maintain the weapon properly.


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## ben300win (Mar 8, 2009)

Thanks for the info. I need to start working up a load for my AR with some 69 gr bullets. I have not tried shooting anything more than 55gr thru it. I am sure I could get better groups. It is not too bad right now. I would like to put a Jewell in it someday as well. That might help my groups as much as anything.


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