Ideal barrel length for a hypothetical future issued DMR?

AR/M4 AR General Discussion
1

This is a thought experiment.

A brief note on background: I have none. I’m just a civi who enjoys the freedoms of being an American, and it’s entertaining to think about these things.

My most recent build, a 12.5" BCM “do everything under 250 yards” got me thinking. Historically, excluding Afghanistan, the majority of combat engagements occurred under 100m, with 300m being the max distance in Iraq, for example. Thus, a 12.5" barrel should be more than sufficient for the vast majority of situations and, IMO, represents a near-perfect compromise between length and velocity. Something similar to my build below is what I would imagine the “ideal” service rifle being:

If I were issuing this to defend lives, I’d switch the optic to a T2 and use a real stock. One could make a case for a quality LPVO in place of a red dot, and possibly a Geissele MK8 rail substituting the MCMR (mainly for the added rigidity needed for NV devices/PEQs). That being said, I still think the MCMR is more than adequate for lasers and is strong enough, but that’s not really the point of this thread.

So, assuming a 12.5" free-floated rifle is the standard issue, I think it would be necessary for a squad to have some form of long-range capability too. What would a similar DMR look like? I’m leaning towards an 18" or 20" rifle to try and squeeze the maximum velocity out of the cartridge as possible- the AR was designed around a 20" barrel after all. This build would be the same as the 12.5" carbine in every way except for barrel/rail length and optic. While a 16" could work too, I don’t see the point in going shorter, as we already have a fairly short mass-issued carbine. A larger difference in length between the two feels appropriate to me, but this can be debated too.

The issued optic can get tricky. I initially thought perhaps a good LPVO 1-8x FFP, but I’m not sure. I’d rather have more magnification. Nightforce makes an interesting 2.5-10x. I also wonder if, in the future, we’ll see some new LPVO’s that range from 1-10x.

If I were to make an “ideal” DMR right now, I’d probably use a 20" stainless rifle-length barrel, a 15" Geissele MK8 rail w/some kind of bipod (Atlas maybe), and the NF 2.5-10x. The rest of the rifle would be as ambi as possible.

So, my conclusion would be a 12.5" for general issue, and a 20" for precision/DMR work. Thoughts? What’s the ideal combo/setup?

2

I’m confused. You’re talking about your personal civilian AR pistol and “issued” rifles and optics. Issued by who? Issued to who? Maybe you could explain it in a different way. What is the purpose of this thread? What exactly are you wanting to know?

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3

If we could issue an entirely new set of rifles to the U.S. military right now (or it could be for contractors, or even just a squad of dudes), what would be the ideal setup and combination? I’m using my personal build as an example of something I think is an ideal setup for a large array of situations; if I were in control of determining what gets issued to everybody, I would choose something similar to the above build. What would be the DMR equivalent?

We know that the military takes awhile to catch up on civilian trends; innovations and improvements hit our markets years before it gets picked up by Uncle Sam- see the recent adoption of the new URGI Geissele uppers as an example (adopted last year- we’ve had that stuff for quite a bit prior).

I’m discussing the ideal combination, barrel lengths, and setups for a carbine and DMR to be used in a squad taking into account the quality, modern gear available on the market. Again, this is all hypothetical.

4

WUT??

5

Here we go again…

6

The response thus far has been oddly dismissive; I used the search feature and didn’t see anything similar regarding a modern 20" DMR in the context I provided. But, if this is a topic that has been discussed ad nauseam, then by all means close the thread. I suppose M4C isn’t interested in hypotheticals. Oh well.

7

Ok I’ll bite…

The short answer is that it would look similar to what’s already out there today… ie the Mk12 Mod 1 and the 16” Recce Carbine, with a few updates…

Barrel: When you’re talking about an SPR / DMR, you’re really talking about the 300-600 meter zone. 600 and beyond your snipers are going to pick up.

The argument for a 16” (or even 14.5”) gun with a good accurate barrel is that for the ranges you’re going to encounter the bullet is still going to stay trans-sonic … leading to a predictable flight path.

18” Barrel does open the possibility of rifle length gas, but mid-length is pretty well shook out at this point.

Remember that the DMR role is 2 faceted - extend the range of your squad / team to hold off mid-range targets, and to be able to hit reduced exposure or precision targets within 600 meters.

A 16” gun meets that need perfectly, and still has a little more oomph to go slightly beyond that. You also get the benefits of lighter weight, better handling, and a shorter overall package.

Optics: I think 8-10x should be the minimum on the top end. Having the extra power of a 3-18 or similar range makes more sense because now you have the ability to not only positively ID targets faster, but also pinpoint the exact placement of your bullet. I’d say a Horus Tremor 3 reticle, but that’s a whole other discussion.

Rail: Go Geissele or go home. It comes down to the barrel nut system. Eliminate any flex where you can… not only important due to NV and lasers, but also for overall accuracy shooting off of multiple surfaces and eliminating rail flex while loading the bipod.

So there you go… your ideal “new” SPR… stuff already in existence and in-service:

16” Rifle Cut Stainless Barrel 1/7 or 1/8 twist - Bartlein / Krieger / etc
Geissele Rail - 13”
Pinned Geissele Gas Block
Leupold Mk6 3-18 Tremor 3
Surefire Can and Mount.

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8

:suicide:

9

Phased plasma rifle in the 40 Watt range. /thread

10

Well the US Army recently decided it needed to be a version of the HK G28 with a 16" barrel and Geissele rail so whats the question?

http://www.snipercentral.com/us-army-selects-hk-g28-sdmr-role/

So I would say a 16" SR-25 type with a 1-8 scope.

11

There’s no need to change barrel lengths just to get a good gas system configuration these days.

Longer than mid-length EXT gas systems are available that are Optimum for 16" barrels.

12

Considering how anemic 5.56 can get at range, wouldn’t you want the most velocity that you can reasonably get? 20" doesn’t /seem/ too long to me, given that the M16 was our service rifle since Vietnam. Is the shortened length that you get with the 16" justified over the loss in velocity you get when going below 18" or 20" for a DMR role?

13

.308 is a whole different ballgame. I’m asking from the perspective of an ideal 5.56 DMR for magazine/ammo interchangeability.

14

Free floated M4A1, Geissele SSF, LPVO and a trained designated marksman.

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The Army has recently determined that the”ideal” SDM(DMR to you) rifle is a 16” 7.62x51. Your perspective of it needing to be 5.56 is flawed. As for “ammo interchangeability”, they can easily delink 7.62 from the M240 or Mk48.

Now, I have first hand experience with the SDM M16A4s built by AMU. They were nice rifles, but were a bit of a pain for maneuverability in vehicles and around buildings. A collapsible stock would have helped greatly. And I also think a 16” free float match barrel with a 2-stage match trigger would have been good too. But, so is a 7.62 16” SDM rifle. And a 7.62 will be less affected by wind at 600 meters than 5.56. Plus, the 16” 7.62 will have a suppressor, so the 16” is needed so it won’t be as long as an M110.

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Oh, and if you’re looking for ammo commonality with your existing rifle because you want an SDM type rifle for yourself and don’t actually care about the “issued” aspect, you’d be fine with a 16” WOA SDM barrel, free float, LPVO or ACOG, and an SSA-E trigger. That will get you from 300-600 nicely. Sure, you’re giving up about 2-3 inches of travel from 10mph wind at 600 yards with 77 TMK, compared to a 20” barrel. But it’ll do and will handle better. The 20”+ should be if you want to extract every last drop of 5.56 performance and don’t mind sacrificing maneuverability.

17

The main concern here is training, not equipment. Secondary but still above equipment is manpower, where the DMR comes from and fits in the Squad or Platoon. Most people don’t understand the DMR doesn’t add someone to the the Platoon.

I think highly specialized rifles are pointless without the DMR being an ASI position at the Platoon level. DMR school should be like the shooting part of sniper school.

18

Agreed. And I’ve brought it up in multiple threads with similar topics, like mass-issuing LPVOs. The bulk of the non-infantry Force can’t even work a CCO. The infantry guys are better, but not nearly as good as you’d hope.

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19

In the Army, there is an SDM course. It’s a week long and incorporates points of instruction on kill zones, external and terminal ballistics, reticle usage, range and wind estimation etc…

And the SDM/DMR isn’t a platoon level position, but a squad level position. Essentially one of the two riflemen in the squad gets the SDM rifle. But I do think it would be good to have as an ASI.

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A week is nothing compared to what it should be. My division’s new marksmanship course was two weeks and did that still didn’t feel long enough.