ripper51

Used the original railed gas block for front sight mounting. Used top rail for rear sight mounting. And for 98Z5V- have no idea who you are or what you do other than post. I do know my limitations though. I have tried 5 different free float tubes. First 3 were from DPMS who installed them, Did not like them because they were basically unvented heat traps. Tried a Daniel Defense modloc ff tube. Felt weird and seemed to put the COG too far forward. Put the Rock River CMP-legal FF tube that looks like the original A1/A2 handguards and it balances and holds right. Magpul front and rear sights are well Magpul front and rear sights. You mount them, zero using a bore laser and the open bore (you know this trick- look down the bore from the breech at a black dot 25yds away with upper in a viseblock). And I am curious- what difference do the various fft or detachable iron sights make if they are installed correctly? I'm looking for a way to inspect the method used to tap the receiver for the barrel as I suspect that as the culprit. Wish I could post pics but camera won't be back from Nikon for a week. No rush here, just looking for ideas. Survivalshop, that is a good idea on lasers. I have enough that I can do bore, sights in 2 ways and barrel alignment. Using a buddy's upper- I'm in El Paso. Don't know anyone close by really that has a DPMS Oracle in 308. Lots of 223 though.

DPMS Free Float Tube, Magpul front and rear sites. What's going on? Kind of apparent to me.Either the barrel was screwed in wrong, cross threaded (not likely- doesn't show when the barrel is unscrewed), or the receiver is slightly twisted- probably the better approach. And when does it matter what brand or type of free float tube or Back Up Iron sights are used, if installed correctly? I had this problem awhile back with a DPMS LR-308 that shot consistently at 2 oclock 12-15 inches out at 200yds. and an equivalent distance at any other yardage. That one turned out to be receiver barrel threads that had been cut wrong by DPMS.

Brand new (May 2016) DPMS Oracle received. BUIS installed. Range report. After Mechanical zero set and boresighted it was apparent something wasn't coming together. 25yd shots high and 11o'clock. Corrected using all sights front (elevation) rear (windage). Rear sight bottomed out at 200. Tried again at 100 and 200 yds. 11o'clock 5 ring. Checked for play in upper and lower-none & tight. Checked barrel- screwed in and torqued 65lbs. Still hitting 11 at 5 ring. Sent back to DPMS. They checked, waved their magic wands and said "Yup, 11o'clock and 5 ring. at 100yds". Shipped it back to me. Took it down, replaced handguards with free float tube. Now its consistent at 11 o'clock 7 ring. Talked with DPMS about shipping up back to have some look at receiver facing and how there could been this much ,

Gas guns are funny beasts. what will pass in a bolt action, will hang up in a gas gun. Crimping too much will definitely swell the shoulder of the case enough that it will keep it from chambering properly. You won't see it with a micrometer but a case gauge might catch it. I use a case gauge but also use the tried and true method of chambering every round after I reload them. Unless you are seating long, shouldn't be a problem checking them that way. DO NOT try to beat them bolt in using the forward assist as that may cause more problems. If the round get stuck and will not extract, take it to a gunsmith who will use a wooden dowell rod to drive the case out with the bullet. This will drive the bullet into the case, compressing the powder and can result in another problem, which is why a gunsmith who is experienced can take care of it. Don't try yourself to use a dowell rod unless you are an experienced gunsmith and are willing to see the rod and bullet come out the barrel at about 2500fps. Makes an interesting hole in the roof of a workshop and a more interesting negligent discharge wound if you are in the way.

Check your rounds and see if you have the tiniest bit of a swell in the shoulder after you have seated your bullet. When you find it, Unscrew the stem a quarter turn, and it will go away. AR chambers don't swell. But seating a round with too much crimp, either taper or regular will slightly bulge the shoulders which will keep the cartridge from seating properly.

RCK can you post a couple of pics?

Yup, A2 sights. The extended post I think may have been an attempt to compensate. Talked with DPMS and they said just go with what the manual has for clicks, minutes, inches. However think the sights are half minute not quarter. Once I walked it in, the groups were cloverleafs at 200yds right on the x. Didn't change when I took it from the Lead-Sled to prone with a sling either. Now I need to work out 300 and 600yds settings and I'll be ready to try it in competition.

I'm actually posting this for posterity. After acquiring the DPMS LR308 Classic, I've discovered many things about it. The detachable handle should not be detached unless you are putting a scope and mount on. The Front Sight is a modified A2. The Front Sight itself is a modified longer body and stem blade. This front sight must be moved UP not in the direction of the markings next to the front sight with and arrow indicating UP. UP by DPMS standards means moving the bullet strike UP. Screw that puppy down by going in the marked UP direction and I'm sure you can reach max ballistic range.....somewhere out there. When you do get the front sight up far enough to make repeated strikes at 200yds in the 10 or x-ring, have it "pinned", which involves simply putting another nut on the bottom of the stem and screwing it in to meet the top nut. The detachable carrying handle has a rear sight capable of elevation and windage adjustments. Trying to match it with the graduated markings of 200, 300, etc is an exercise in futility. If you want precise adjustments, get a match rear sight and have it installed and pinned by a reputable gunsmith (defined as NOT someone who graduated WECSOG). When you Have all that done, relax. It's a shooter. I replaced the handguards with a slotted free float tube. The heat dissipation is such that I can grip the FF tube without melting my best High Power Shooting Glove or Mitt. This rifle likes 168gr FGGM and most reputable military surplus. It DOES NOT LIKE any of the steel cased ammo as it has broken more extractors than I care to remember. I don't use any buffers or buffer softeners. It doesn't need it. It has taken me two years to get to this point because frankly I haven't been in a hurry as I shoot my Springfield M1A for High Power.

Flatlander, welcome to the site. A more knowledgeable and outspoken group on the topic of AR 308's you won't find anywhere else. Handguards vs Free Float tubes is where you are at. All handguards are relatively inexpensive. Free Float tubes cure a number of issues with accuracy. I fully intend to use my LR308 Classic in competition. So I searched and found several free float tubes that also function as handguards. I currently have an LMT free float slotted tube in place while I wait to buy the Troy Industries Rifle FF tube. In my mind, clamp on or snap on doesn't solve the problem of the barrel being pulled towards the shooter when the shooter is using a sling. And while this isn't a 223 clone with a thinner barrel, there is still some twisting and bending imparted. Enough for me to group nicely at 11 o'clock from 200yds with standard handguards and to cloverleaf the x-ring at 200 with the FF tube. If you can put the money out, call Troy Industries and have them walk you thru getting the right one. Nope, I don't work for them or sell their products. Just been suitably impressed in dealings so far.

DPMS customer service is actually much better than some give credit for. They will indeed make it right, just put a letter in with a complete description of this problem and all the other problems. A word of caution though. This is National Matches week coming up and many of the DPMS folks may be at Camp Perry. It may take a little longer than usual to get the rifle back.

Have now become comfortable with 8 pound maul and taper punch to remove said pins. Took off old handguard. Put on non-vented free float tube, took off free float tube put on and took off 4 other free float tubes. Finally settled on the DPMS vented free float tube. Used new taper pins and a couple of new roll pins. Glad I listened to you all as it is a bear at first. Thanks for advice. And thanks to Robocop for leaving us all with that indelible image of his issues. :))

Thanks to all for the comments. I am "spoiled" I guess by the M1A. AR15 & M16's I have had had a tendency to run a tad hot but you sort of expect that in certain situations. Ar15 that was set up as a Service Rifle for High Power and CMP matches never ran hot. I am shooting a larger round in a larger barrel and expected some heat but not like I was getting. So far this vented DPMS seems to satisfy me. Probably as close as I will get to using an AR10/DPMS LR308 in a match will be local matches. Think I also need to re-think the rear sights and call in an expert (or send it to one). While at first I thought of tricking this out to closely resemble the M110, it probably would cost me the equivalent of an M1A Supermatch. Probably will keep this one as it and use it to annoy anti-black rifle liberals.

Saw a lot of 3 gun shooters on the website. Looks like the heat sink is built for their barrels and weapons. Good idea though. Thanks

Know anyone who uses them>?

@survivalshop. Not sure who JP is. Have seen aluminum inserts under handguards for years. Do not have this problem with M1A and it has a solid fiberglas handguard.