DMR build help

[Jedi5150]

Hello all, I've got a new toy that I absolutely love. My first AR in years is my new SIG 516 Patrol:

I got it with the intent of turning it into a DMR type rifle, and would love to know some ways to stretch it's legs or find out what kind of results I might expect.

So far it has what you see in the photo, an ACOG TA11MGO-M249, graduated to 1,000m. I LOVE this scope. Also on it (but not in the photos), is a Harris swivel/notch bipod and GG&G rail adapter. I plan on switching out the GGG for a LaRue, since I love LaRue stuff and want a QD for my bipod.

The trigger is heavy. SIG lists it at 7.6 lbs on their website but I honestly think even that is a couple pounds conservative. I can rest the entire weight of the rifle, including ACOG and Harris on one finger on the trigger and it won't break until I add downward pressure with my other hand. I now have a Geissele SSA-E trigger on order. I like the CTR stock, which I've had on a couple AR's, but I'd really love the PRS. My only fear is that I don't want to screw with reliability by switching out to a rifle length buffer and tube.

I'd love to hear any suggestions for increasing accuracy, as well as what kind of results I could hope for if I do my part.

 

[Armed Ferret]

how will a rifle buffer and tube "screw with reliability"?

as for increasing accuracy, you forgot to mention how it currently shoots and by what amount you would like to improve however it currently shoots.

 

[Jedi5150]

how will a rifle buffer and tube "screw with reliability"?

as for increasing accuracy, you forgot to mention how it currently shoots and by what amount you would like to improve however it currently shoots.

Hi AF, sorry for the confusion. By referring to the buffer tube I meant everything that goes with it, tube, buffer, and spring. Those three components can obviously have a negative impact in reliability of an AR, hence the different design of various buffers. Sorry if I'm still misunderstanding you.

It's still brand new, but so far the results have been inconsistent. I've been using 75 grain Hornady TAP, since that's what we get at work. I also want to pick up some 69 and 77 grain Black Hills SMK and some FGGM in 69. I was shooting from a bench, both with sandbags and Harris bipod. I'd get a couple bullets nearly touching each other at 100 yards, then the next four or 5 shots would be all spread out over roughly 3". I know a lot of it is my ignorance and lack of marksmanship abilities. All the carbine training I've had has been close-in type stuff, and I'm a rookie at long distance shooting. My plan is to use the 75 grain TAP until I improve my skills a bit, and then try out the different ammo brands.

My goal would be to get to a consistent 1 MOA. I'd love for it to shoot smaller, but I don't know if that is a realistic expectation from either myself or the gun. I'm not sure what all parts SIG uses in their 516's. The gun certainly has a quality "feel" to it, but I never expected it to be a varmint gun. For that matter I don't know if even 1 MOA is a realistic expectation, but that's what I'm working towards. Like I said, I'm not a great rifle shot, but I'm curious if anyone has educated guesses at to what the rifle might be capable of if I do my part.

 

[BCP]

It's already a 'DMR' more or less.

Work up a load with 69s or 77s, once you get your giessele trigger you will be able to shoot a bit more consistently with it. If you want something more accurate think about building a second upper with a decent 18-20" stainless barrel and free floating handguards, scoping that and then swapping between the two. I wouldn't swap out the stock there's no need to although you might want to move your optic slightly forward so that you can shoot with your nose to the charging handle for a more consistent cheekweld.

 

[Jedi5150]

Thanks for the feedback BCP. Believe me, I've considered a second upper and optic for sure. As a matter of fact, it's already picked out, a Noveske 18" upper and Nightforce 2.5-10x42 with LaRue mount. Unfortunately, those are a long ways down the road, now that I have this new purchase. My gun spending is on temporary hold aside from ammo. I could save up for a PRS stock easy enough, but not a whole new upper and the scope I want.

I think I'm going to try to master what I've got right now, which I'm hoping for some pretty nice improvement with the trigger and more trigger time. Who knows, if I can start getting some consistent results it might curb my desire for an SPR upper. I've used the NTCH for iron sights and Aimpoints, but I haven't tried it yet with this ACOG. I'll have to give it a shot.

 

[LRRPF52]

Get some formal training in a DM course first off. That will give you a much better idea of the parameters that you can realistically expect to employ the carbine for practical precision work.

I personally stay away from op-rod designs when looking for accuracy, and the guns that show up to my courses are usually 1/2 MOA to 1 MOA blasters, with Mk.262 MOD 0 being the most popular and consistent loading. We spend 75% of the course shooting from positions other than the prone, so I personally like high quality barrels and uppers, correct build formulas for the guns, solid optic mounts and compact optics with forgiving exit pupil (not ACOG), and all the components balancing well in the hand.

Front-heavy guns don't do well in positions, so I avoid them for my personal guns, and advise others the same. When you get a carbine that feels right in your hands, you tend to be able to shoot with it much better than one out of balance.

The formula for accuracy starts from the barrel and works outwards from there. Next is the upper receiver with a square face. Then the bolt and extension interface, then the...etc. etc.

 

[Jedi5150]

Get some formal training in a DM course first off. That will give you a much better idea of the parameters that you can realistically expect to employ the carbine for practical precision work.

I personally stay away from op-rod designs when looking for accuracy, and the guns that show up to my courses are usually 1/2 MOA to 1 MOA blasters, with Mk.262 MOD 0 being the most popular and consistent loading. We spend 75% of the course shooting from positions other than the prone, so I personally like high quality barrels and uppers, correct build formulas for the guns, solid optic mounts and compact optics with forgiving exit pupil (not ACOG), and all the components balancing well in the hand.

Front-heavy guns don't do well in positions, so I avoid them for my personal guns, and advise others the same. When you get a carbine that feels right in your hands, you tend to be able to shoot with it much better than one out of balance.

The formula for accuracy starts from the barrel and works outwards from there. Next is the upper receiver with a square face. Then the bolt and extension interface, then the...etc. etc.

I appreciate the feedback. I'd love to get into a DM course, but I wasn't aware there were any outside the military. Thanks for the insight on what works and what doesn't as far as balance, DI vs op rod, etc. That said, I just bought this carbine and I'm in love with it. If it's not ideal I can live with that, as long as I'm happy with it. My goal is to have a carbine/ optic platform that can get consistent results a little further than a gun with only a red dot or iron sights. From reading the FM on marksmanship, it seems like 250-500m is the ideal operational environment for a DMR, and that's what I'm shooting for. I guess what I'm trying to say is that the weapon is already purchased, and although it might not be perfect, it's not bad by any means either. I'm not so much asking for advice on what I should have bought instead, but more on how to get the most out of what I have. In that light, your recommendation for a good course landed squarely on the mark.

I'm a little curious as to the bias against ACOGs. My understanding is that the ACOG is sort of purpose-built for the qualities needed in a DMR. It is everything you described; a compact, solid mounted (extremely) optic with an outstanding eye relief (at least the one which I chose for that reason, the TA11). Maybe I'm wrong, but I think of SPRs and DMRs as being in two different categories. I'm curious as to what optic is better than a long eye relief ACOG for a DMR in your experience. I'd guess you're meaning something like a Short Dot?

Eventually I'd like three AR set-ups. My issued weapon at work is my "entry/ patrol" carbine, and is set up with an Aimpoint and a weaponlight. This new carbine I'm trying to fill the DMR role, and eventually I'd like an SPR for even further distances and better accuracy.

 

[BCP]

Nothing wrong with the ACOG just low magnification and short eye relief. I'd keep that rifle as-is and just continue shooting it.

 

[Sterling Shooter]

I appreciate the feedback. I'd love to get into a DM course, but I wasn't aware there were any outside the military. Thanks for the insight on what works and what doesn't as far as balance, DI vs op rod, etc. That said, I just bought this carbine and I'm in love with it. If it's not ideal I can live with that, as long as I'm happy with it. My goal is to have a carbine/ optic platform that can get consistent results a little further than a gun with only a red dot or iron sights. From reading the FM on marksmanship, it seems like 250-500m is the ideal operational environment for a DMR, and that's what I'm shooting for. I guess what I'm trying to say is that the weapon is already purchased, and although it might not be perfect, it's not bad by any means either. I'm not so much asking for advice on what I should have bought instead, but more on how to get the most out of what I have. In that light, your recommendation for a good course landed squarely on the mark.

I'm a little curious as to the bias against ACOGs. My understanding is that the ACOG is sort of purpose-built for the qualities needed in a DMR. It is everything you described; a compact, solid mounted (extremely) optic with an outstanding eye relief (at least the one which I chose for that reason, the TA11). Maybe I'm wrong, but I think of SPRs and DMRs as being in two different categories. I'm curious as to what optic is better than a long eye relief ACOG for a DMR in your experience. I'd guess you're meaning something like a Short Dot?

Eventually I'd like three AR set-ups. My issued weapon at work is my "entry/ patrol" carbine, and is set up with an Aimpoint and a weaponlight. This new carbine I'm trying to fill the DMR role, and eventually I'd like an SPR for even further distances and better accuracy.

I've assisted the USAMU in their delivery of SDM training since 2004; and, I teach a facsimile of the course for folks like you and me. The SDM course is essentially basic marksmanship training with as issued iron sights and ACOG. The military course covers: the principles of shooting, the elements and factors of a solid position, wind and weather effects, ballistics, zeroing for a BSZ with BDC function, shooter/target analysis, angle shooting, range estimation, and moving target favors. It is an awesome course. Covering most everything important to good shooting, it helps shooters get good hits at mid range (300 to 600 meters) which without such training would not be likely. Interestingly, the original SDMR as built by the USAMU was for the most part a match conditioned M16A4 with a Daniel Defense M4 rail. Since there were relatively very few of these the course emphases has been on the SDM being able to get results with a rack grade M4. Getting good results with the M4 and ACOG at 600 meters is pretty easy shooting Mk 262.

 

[Scottmilk9]

Good training is legit, but don't forget what makes an accurate AR in any caliber is barrel and trigger. Also, you must ask yourself what you expect out of this rifle. Are you looking for 1/2" groups or trying to hit a man target at 800yds?

 

[Jedi5150]

Good training is legit, but don't forget what makes an accurate AR in any caliber is barrel and trigger. Also, you must ask yourself what you expect out of this rifle. Are you looking for 1/2" groups or trying to hit a man target at 800yds?

Definitely not a 1/2" as my goal for this weapon. I'm more hoping for man-size targets at 500-600 meters. I'd be stoked if it (and I) end up being 1 MOA shooters. I'm really not expecting under 1 MOA with this set-up. I could live with 2 MOA, but I'm really hoping for better.


SterlingShooter, that course sounds like a blast. Most of the carbine courses I see are far more tailored around close-in ranges. I'm not saying that more training ever hurts, but I already get some short range carbine training at work and a couple work related courses. I'd really enjoy a class that specializes more in marksmanship fundamentals and increased range.

 

[LRRPF52]

Unfortunately, the USAMU is one of the only ones really supporting the DM program from a training standpoint, even though it is now on the books as an MTO&E slot in the infantry squad.

The ACOG is a great general issue optic with intuitive BDC for 5.56, but is unforgiving in terms of eye relief and exit pupil. It is a tough scope that can take a lot of abuse by entry-level soldiers who don't have an appreciation for caring for weapons and especially optics, and serves well in that regard.

I personally prefer compact variable tubes that are well-built, but an ACOG is plenty capable of getting it done.

At this point, I would start looking at fundamentals, natural point of aim, and working the system with some quality ammunition to see what she will do. This will best be done with someone who has a lot of experience driving AR15's in that role, namely a trained DM or Sniper who has a true passion for the skill set and is good at teaching.

1.5 MOA is actually doable for even a 600yd gun, but in an LE capacity, those distances are going to be extremely hard to justify in an Officer Involved Shooting. What I would structure for an LEO in a coastal municipality in a temperate zone is drastically different than what I do for closed courses with other organizations.

Regional orientation is huge for me when structuring my POI for a course. Geography & climate drive everything. I look at weapon configuration differently based on regional factors as well. An 11.5" carbine with tight twist is plenty fine for forested areas with little or no elevation and relief, as it's hard to find 300m clearances, whereas out here in the West up in the mountains, you can't bring enough gun, but thin air requires you to look at lightweight bigtime.

As far as equipment is concerned, get a good 2-point quick-adjust sling, and start working on positions. Get out of a prone-oriented comfort zone, and start building modified kneeling, vehicle barricade, under the car, squatting, standing supported, and other positions with the sling, and conduct safe dry-firing exercises where you call each shot. I do this all the time, and it makes a world's difference in how fast and accurately you can get into uncomfortable positions, and quickly break a shot on target. It is one of the paths least traveled in this skill set.

 

[Sterling Shooter]

Jedi,

I don't know that discovery is a blast for anyone except folks like you and me. But, most folks taking the facsimile simply remark that they did not know anything about what was presented to them. That's to say, most folks have a notion about marksmanship which is not anything like what is really important to good shooting. However, once these folks abandon all the inappropriate luggage for the right mindset, good shooting is well within their means. My course does not include a moving target session and does not have four and a half days of range work. It is mostly classroom, about 4 hours, and just 2 hours of range to get a BSZ and thereafter learn how to get consistent sight alignment using irons and trigger control from a rack grade trigger, with evidence of success as seen on the MR-31 target. Nothing exciting, just an orientation of basic marksmanship very similar to Small Arms Firing School. In fact, if I were you I think I'd be more inclinded to participate in SAFS before taking a class like the one I teach. SAFS will be held at Camp Perry this year July 15-17. It is taught by the USAMU Service Rifle Team with support from All Guard, Reserve, and SDM instructors.

 

[Jedi5150]

Thanks again you guys. LRRP, sorry I was unclear about my reason for getting a DMR and SPR set-up. It's purely for hobby and trying to increase a skillset. My work carbine is the only gun I'll be able to use on duty...we're not allowed to use personal weapons. My comment earlier was just that I'd like an AR I can use for each different range set, even if two of the three are just for fun. And thanks for the ACOG explanation, it makes sense.

SS, thanks for the info. I'm going to follow both of your advice and focus on basics.

 

[Zebra644]

I'd also re-think that PRS stock for a couple of reasons. It's a great stock for a prone rifle and is kinda akward and the heaviest stock Magpul has. You would also have to buy a rifle lenght tube, buffer and spring so more money. Look at a UBR they are not as heavy, (also helps if you remove the storage doors), as the PRS a little less expensive depending on where you go, and will allow you to to use your carbine buffer and spring and you wont have to worry about the buffer tube. Also it will give you the best of both worlds you can have a carbine stock, then extend it to a rifle lenght LOP and no slop or play. Just something to think about

 

[Armed Ferret]

I'd also re-think that PRS stock for a couple of reasons. It's a great stock for a prone rifle and is kinda akward and the heaviest stock Magpul has. You would also have to buy a rifle lenght tube, buffer and spring so more money. Look at a UBR they are not as heavy, (also helps if you remove the storage doors), as the PRS a little less expensive depending on where you go, and will allow you to to use your carbine buffer and spring and you wont have to worry about the buffer tube. Also it will give you the best of both worlds you can have a carbine stock, then extend it to a rifle lenght LOP and no slop or play. Just something to think about

Along that line of thinking, I gotta throw a plug for the Ergo F93 stock. Adjustable, completely solid lock-up, and it's around 150 bucks street price (possibly less before shipping depending on where you find it). I have a couple and absolutely LOVE it for an adjustable stock.