Have had a pair for a while and this is my experience with them.   I originally wrote this to an acquaintance who just got one.

I have two DPMS, one 18" with iron sights and a JP trigger and a 24" fluted with Nikon scope and bipod with a Geissele 2 stage trigger.  I use AR-Gold in my other rifles now and would have used on in those if I knew about it at the time.

Both rifles took about 300 rounds to settle down, and seemed to improve after I got them real hot in one episode.  

I added 2 or so pounds of lead to the buttstocks to help with recoil for target shooting, but the big one is like 17#.  Only good from a bipod or rest.  The 18" is about 13# so I can JUST horse it up into a reasonable standing position.

I made the handgrips from a regular stock grip with about four sticks of epoxy, molding to my hand, a dremel to smooth it, and some paint.  I will redo the paint now that I see how to get the layers to work better.  Key being multiple thin layers with a lot of matte clear on top.  I have long hands and these make a HUGE difference to me.  And they add a little weight in a good place.

The hands down BEST ammo is Federal Gold Medal Match, 168 or 175, doesn't seem to matter out to our 600 yard limit.  Expensive, but consistent.

I use Mobil1 to lube it.  Actually Mobil1 10-40, Marvel Mystery Oil, and ZMax mixed 4:1:1.  Works fine and is pretty cheap all together.  I run them WET with lube.  Very drippy wet, oil blowing in the wind - wet.

Have had one firing pin retaining pin break and DPMS sent me four for free.  These are the solid style, not the cotter pin style so common on AR15.

Technically, the rifle is NOT an AR10, as it is very different (not receiver interchangeable) with the Armalite AR10.  They are called an SR25 pattern, and use that style of mags.  I have never had one misfeed issue with either.  Use DPMS 19 round mags.  I do also a lot of hand-feeding one at a time, which is a habit from competition slow fire.  I like the control it gives me and the challenge of maintaining position during the loading and release of the bolt.

The Afghan wrap ain't pretty but it is hot down here and it feels good.  I get a good grip with my cheek beard on it.  

I have found that I shoot better off sandbags than the Harris bipod on the 24".  I think 24 is overkill, and would be happy with 20" for long distances.  Everything I have read says the added rigidity will offset the loss of velocity.  And the 18 seems to shoot just as well out to 600 yards.  

I clean them with only patches on a brass jag and stainless rod.  The graphite rod I got cracked in the bore guide on an AR15.  I do not use bore snakes or anything that passes through the barrel more than once.  BoreTech cleaner with final swipes of Kroil.

I use my weak hand to hold the butt in my shoulder when I shoot on a bench or bipod.  Otherwise with the 18" I use a sling with a 3" wide cuff.  I assume your handguard is the free float model, where nothing touches the barrel at the muzzle end.  I am considering getting the handguards drilled or slotted for ventilation since the bbl gets so damned hot.  I keep a can of compressed air in the bag to cool it when I have to shoot a lot.  Worked real good sprayed in the perforated breech end.

I had a hard time getting the right height rings for the 24" to get a comfortable cheek weld.  I now know that the A2 standard stock is a bit too long for me, though I am 6'2" with long arms.  One day I may get an adjustable stock so I can lose 1 to 1.5".  This would help on the 18" standing, and the 24" prone.  But it would be hard to retain the weight I like in the buttstock.  On an AR15, I used an adjustable Vltor with battery storage and put lead shot in them.  This was good for over a pound and I get the adjustability.

I shoot targets for accuracy, and not being LE or MIL, I don't carry them around.  So the weight is important to me so I can regain sight picture after a shot.  The 18" stays almost exactly on target after a shot, if I do my part.  My .223 stays RIGHT ON target using 2# of lead in the butt..  

That is everything I have learned in the two years I have had them.  Unfortunately, I do not shoot them that often, due to working on my skills with a .223.  And the ammo is frigging expensive, since shooting low accuracy ammo is a waste of time.  Dry firing is more valuable practice than shooting crappy ammo.

Pix of course:

24" fluted barrel, slick side upper, Geissele 2 stage:


24" fluted barrel, slick side upper, Geissele 2 stage:


18" bull barrel, now has front aperture sight, JP trigger:


18" bull barrel, now has front aperture sight, JP trigger:


End of story.

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