Rick O'Shea

It will fit. Gas block total height is 1.572". Handguard ID is 1.75" All this was checked before I ordered either one. Why do you ask?

I did a search for air can test. I found four entries, two in this thread. The other two indicated that the test consisted of shooting pressurized air into the gas system to see if it will push out a piece of brass placed in the chamber. This would rule out a complete blockage but not a partial one. I currently have no location available to fire the rifle. That will change soon, but in the meantime I'm changing the configuration to match my preferences regarding the feel and look of the gun. I wanted a long handguard. This dictated changing to a low-profile gas block. I reload, and will be tweaking loads for the gun. I prefer the flexibility that an adjustable block offers.

MikedaddyH, I have not personally shot the gun, but the gentleman I bought it from test fired it a few times and said it ran perfectly. That was in its original configuration with the factory DPMS gas block. I do not plan to use a suppressor in the near future. I measured the distance from the gas port inside the block to the block's proximal edge, then marked a line on the barrel from its gas port of the same distance. I test fitted the gas block lining up the block edge with the mark on the barrel. When I tightened that set screw into the dimple, the block only shifted a hair. If any drilling needs to be done, I will let my gunsmiths do it. If they have a borescope, I may have them check the gas port alignment as well. What is the air can test? This is my first AR of any kind. Thanks for the assistance.

OK, I feel better now. Thanks.

Greetings, all. I have a DPMS 24" bull barrel, and have purchased a Syrac adjustable gas block for it. I got the set screw version because when I removed the stock gas block it was set screwed into dimples on the barrel. Well, guess what? The spacing of the Syrac set screws is approximately .195 longer than the DPMS block. I can tighten the screw closest to the receiver into its corresponding dimple (and the gas holes appear to line up - I measured), but the distal screw is hitting undimpled barrel. Is it OK to just tighten it up this way? I'm getting the barrel Cerakoted, and the people doing it are full-scale gunsmiths with a machine shop. Would it be better to have them add a dimple to match the Syrac block? I hate to spend money I don't have to, but I do want to do this right. Any thoughts, opinions and observations are welcome.

Arrived the other day - very nice looking piece of equipment. I am accumulating the necessary tools and equipment, and will start assembly as soon as I can get the barrel Cerakoted. Thanks again to everyone for their support and assistance. I'll ask for help again if I need it during assembly, but honestly, I feel pretty good about it.

Thanks, survivalshop The terminology I used was JP's, from their instruction sheet, since at this point I don't know my nuts from a hole in the ground. I'll use the red Loktite, then. I'm not planning on redoing this configuration anyway, and I do have a heat gun if I have to for any reason. And you're saying that aligning this part will automatically index the handguard itself properly? Because I'll be putting a front sight rail and a bipod rail on this, and I need them to be perfectly plumb. Not sure I can eyeball that well enough. Thanks again everyone.

OK, did some you-tubing and general poking around, and then re-read the directions. It looks like if I go one step at a time, it should be pretty straightforward. A couple of things, though: I'm concerned about using red (permanent) Loktite on the barrel nut. I gather it's done to keep the nut in alignment while torqueing down the barrel retainer nut, since the odds of it clocking perfectly snug to the receiver are nil. Some people are using a rod or drill bit through the gas hole to accomplish this, though, even foregoing Loktite altogether. My thought, being cautious regarding either extreme, was to use blue Loktite, and use a mechanical alignment while it sets up. Also, the instructions have you putting the barrel in after the barrel nut. Any reason for this? What do you think about the Loktite vs. no Loktite method? And why the back-and-forth tighty-loosey torqueing method? Thanks as always for your assistance.

Well, I ordered it. Also ordered the rails I need directly from them. Doubt I'm up to turning my own screws, but I like your style - waste not, want not. I looked at the instructions, and I confess, they're a bit intimidating. I fancy myself a fair kitchen-table gunsmith, but almost all of my experience is with Smith & Wesson revolvers and 1911's. This may be a matter of it reading harder than it actually is, or my inexperience with the general AR platform may be a factor. This .308 is my first and one-and-only AR of any type. I appreciate the offer to assist me in the process, and I may take you up on it. Y'all have been a great resource so far. One thing I've developed as an amateur gunsmith/carpenter/handyman, etc... is a keen sense of when I'm about to get in over my head on something. If that happens, I'm fortunate enough to have an excellent (professional) gunsmith just up the road. More on this crisis as it develops....

Follow-up: I'll be dadgummed if water didn't do the trick! Wrapped a hot water-soaked washcloth around the area of residue for a few hours, rubbed it good, and no more glue! I dried the barrel off and wiped it down with an oily rag, and everything looks perfect. Y'all are awesome. Thanks!

Thanks for the input. The only rails I want are a front sight rail, and maybe a short rail at 6:00 for a bipod. Otherwise I want to be able to get a full wrap-around hand grip on the guard. Glad to hear they're good stuff, 'cause they're all I've found that fits the bill. Guess I'll pay the price. I guess Karma's a bitch; I got such a good deal on the basic rifle, that now everything I want to add to it is another $200.

OK, I started with some basic ideas and preferences for a handguard: round (no quad rails or full length rails), slotted for ventilation, and long enough not to look out of proportion with my 24" bull barrel. Alas, many options for AR-15's, but damn few for .308, with the usual compatibility issues. The one that seemed to meet all my needs was the JP Enterprises Mk III Signature. JP seems like a quality outfit, and they're certainly proud of their products: $200+ for a handguard is getting a bit special. Still, if it's worth it as a matter of quality, maybe I can choke down the price. I've looked high and low for alternatives, and have come up short. Also, their 17.25" length is the longest I've found, and looks the best with my barrel (tested by cutting pool noodles to 15.5" and 17.25" lengths; perfect fit over the bull barrel). I looked around here some, and have found a few references to some of their other products, but nothing about the handguards. I'd welcome any input the community can give me on this product. Thanks.

Water? Who'd a thunk it? The universal solvent. Never crossed my mind. I think glue solvent and something organic like acetone or toluene seems appropriate. Huh. Thanks, guys!

Thanks for the welcome. I thought of checking with DPMS, and still might. Frankly, I was interested to see if this problem was common, or had at least been encountered before.

Hey folks, I'm working on changing some stuff out on a DPMS LR-308 with a 24" SS bull barrel. The gas block was apparently glued in place at the factory, but the dried glue was brittle enough to break loose with a little effort on the set screws. My issue is with the glue residue left on the barrel. I want to get this barrel Cerakoted, so it needs to be perfectly clean before I give it to the finishers. I've tried a number of solvents, including mineral spirits, denatured alcohol, kerosene, lighter fluid and Goof Off. Before I go to the hardware store and buy quart containers of paint thinner, MEK and acetone, I'd like to tap the wisdom and experience of the group to see if any of you have successfully tackled this particular issue. Personally, my money would be on acetone, but I'd like to hear what y'all have to say. Thanks, everyone.