I'm kinda of new to ARs. I have an AR-15 colt, and am looking to go up in caliber. Can a 260 upper be put on a AR lower and where is a good place to buy one. Also, what caliber can be put on an AR 15 lower? Thanks for the help

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Originally posted by eyeman:
I'm kinda of new to ARs. I have an AR-15 colt, and am looking to go up in caliber. Can a 260 upper be put on a AR lower and where is a good place to buy one. Also, what caliber can be put on an AR 15 lower? Thanks for the help

First a 260 can't go on an AR15. The cartridge is too long and too high pressure for the AR15 size bolt. The 260 has to go on an AR10.

Be aware that some Colts were made with two different size take down pins. All the AR15 uppers, except for Colt, won't fit in that the pin holes are wrong and you'll need a pin adapter. The problem is the front pin called the hinge pin sometimes. All the rear pins are the same size. Lots of places sell the front hinge pin adapters.

As noted, the .260 won't work. You could go for a 6.5 Grendel or a 6.8 SPC. Either will fit in an AR-15. I'd probably opt for the 6.8 SPC because there seems to be more factory loaded ammo around for it.

If you do not handload I wouldn't recommend 6.5 or 6.8. I have a few 6.8's and love them. But I handload. Otherwise feeding them is pricey.

Just an opinion, but go for the 6.5 just because you will have a very wide selection of bullets that are designed for attainable velocities.

Course I like 6.5 anything.

My spare upper is a 16" 7.62x39 DPMS. Is VERY reliable with Colt Mags. Lower is a Bushmaster.

Original upper is a Bushmaster fluted Super Varmint .223 24". At first it was very inaccurate (3"-4.5" 3 shot groups at 100 yards). Bushmaster refused to do anything, saying the accuracy was satisfactory by their standards, so I fire-lapped the .223 chrome-lined barrel as a last resort.

Now that barrel will shoot sub-MOA 10-shot groups. Must have had a humongous burr in there somewhere.

I've heard horror stories about the 7.62 with other makes of mags, but I have never tried any other than the Colts, which I bought on sale at CDNN. Mine has NEVER failed to feed pointed milsurp ammo, or jammed. So I have no horror stories to tell about it and like the chambering very much.

Matter of fact, I bought the mags before I ever bought the 7.62 upper. I got the upper complete with bolt, carrier, etc. for $400 (IIRC) from an outfit called "Cobra" in Southern Cal.

I have two besides the .223.

The first one is a S&W 5.45X39. It runs 100% reliable and it's reasonably accurate. I can get 5 in a 1 1/2"-2" group at 100yards and every now and then get an MOA group. The most appealing thing about this one is the cost of ammo. A 1080 rounds will run you a $119 last time I looked. This is one I can afford to shoot. The downside is component and ammo selection. It's almost non-existant. Mine is basicly a plinking rifle though and it REALLY likes surplus ammo so it's not a problem for me.

The second one is a 6.5 Grendel. It's made of light weight components and shoots like a dream. I'm planning doing some hunting with it this year. The Grendel is a great choice for an AR-15. Most are very accurate and it has about the same trajectory as a .308 with a 150gr bullet. The only draw back is like mentioned above, it cost a lot to shoot. I basicly shoot mine like a bolt gun. I take VERY careful aim and will not pull the trigger until all is right with me and the rifle, unlike with the 5.45X39, when I get a flier with it I just smile and shoot another. With the Grendel, if I shoot a flier I gremice .

Thanks for the input. I got a 6.5 Grendel upper and a Timney trigger. Can't wait to shoot the new Rifle.