The Firing Line Forums

Go Back   The Firing Line Forums > The Hide > The Art of the Rifle: Semi-automatics

Reply
 
Thread Tools Search this Thread
Old August 19, 2018, 11:30 PM   #1
Model12Win
Senior Member
 
Join Date: October 20, 2012
Posts: 5,797
Compact DMR Build?

I am thinking of making a 16" DMR that would be lighter and handier than the 20" US military DMRs.

16" match grade fluted heavy barrel w 1/7" twist.
Free floated handguard
Bipod
Geissele trigger
4x ACOG

Thoughts?
Model12Win is online now  
Old August 19, 2018, 11:46 PM   #2
lordmorgul
Member
 
Join Date: August 18, 2016
Posts: 99
Quote:
Originally Posted by Model12Win View Post
I am thinking of making a 16" DMR that would be lighter and handier than the 20" US military DMRs.



16" match grade fluted heavy barrel w 1/7" twist.

Free floated handguard

Bipod

Geissele trigger

4x ACOG



Thoughts?
223 Wylde chamber

Why fixated on 16” particularly? Going with no muzzle device also for compact length?

At 16” you’d be better off running 6.5 Grendel. The extra 4” actually does make some difference for >600 yards in 5.56. Planning to run 75 Hornady OTM or 77gr SMK if staying in 5.56?



Andrew - Lancaster, CA
NRA Life Member, Calguns.net contributor, CGF / SAF / CRPA / FPC / USCCA member
lordmorgul is offline  
Old August 19, 2018, 11:57 PM   #3
DubC-Hicks
Senior Member
 
Join Date: December 20, 2009
Location: Backwoods, Northern MI
Posts: 916
So you're pretty much thinking a RECCE build. If it was me, I'd do a Faxon Gunner profile 16" with a 1-6 scope.

I really like my 18" Faxon gunner 5.56 with 1-6 Primary arms scope. It'll do 1" at 100yds with good ammo. Very easy to hit silhouettes out to 500
__________________
”Gun control is like trying to reduce drunk driving by making it tougher for sober people to own cars.” ~Unknown
DubC-Hicks is offline  
Old August 19, 2018, 11:58 PM   #4
Model12Win
Senior Member
 
Join Date: October 20, 2012
Posts: 5,797
Quote:
Originally Posted by lordmorgul View Post
223 Wylde chamber

Why fixated on 16” particularly? Going with no muzzle device also for compact length?

At 16” you’d be better off running 6.5 Grendel. The extra 4” actually does make some difference for >600 yards in 5.56. Planning to run 75 Hornady OTM or 77gr SMK if staying in 5.56?



Andrew - Lancaster, CA
NRA Life Member, Calguns.net contributor, CGF / SAF / CRPA / FPC / USCCA member
I'd be staying in .223/5.56 and running 75-77 gr. OTM. No interest in the Grendel at this time. Great round, but not for me.

I guess I'm wanting something of a RECCE rifle. Wanting to maximize accuracy and effective range and using the heavier weight ammo but to retain more usefulness in closer quarters and less weight bulk over a dedicated 20" DMR.
Model12Win is online now  
Old August 20, 2018, 12:18 AM   #5
lordmorgul
Member
 
Join Date: August 18, 2016
Posts: 99
Quote:
Originally Posted by Model12Win View Post
I'd be staying in .223/5.56 and running 75-77 gr. OTM. No interest in the Grendel at this time. Great round, but not for me.

I guess I'm wanting something of a RECCE rifle. Wanting to maximize accuracy and effective range and using the heavier weight ammo but to retain more usefulness in closer quarters and less weight bulk over a dedicated 20" DMR.


Not familiar with that Faxon profile suggested but look at the Ballistic Advantage Hanson profile as well. It’s added weight over pencil but a lot less than a heavy SPR which you usually don’t even find less than 18”. It is a very good barrel.


Andrew - Lancaster, CA
NRA Life Member, Calguns.net contributor, CGF / SAF / CRPA / FPC / USCCA member
lordmorgul is offline  
Old August 20, 2018, 01:57 AM   #6
marine6680
Senior Member
 
Join Date: July 24, 2012
Location: Parker, CO
Posts: 4,550
That is more of a recce build. It can be a very good build for a range of roles, if set up well.

My current recce has an ACOG and offset RMR. After a lot of thought and going on my experiences with the LPV scopes... I decided that they simply are not a replacement for a red dot on 1x.. Not in any kind of real world situations where things don't always go perfectly. LPVs are fine on 1x if everything is going your way, and there are no suprises... But when is that ever a realistic expectation... And if that is the case, why not just have a red dot on an offset mount, and then why have a variable at all if I won't be changing magnification. So I went ACOG... An ACOG with a third party mount, and an RMR in an offset mount, combined... Weigh less than a LPV with mount.

This setup will work well for reaching out to 500yds with better precision, but still be useful and fast inside 25yds using the offset red dot. In mixed terrain, where you go from fairly open areas, into areas that are more confined and present points where close range may be a factor.


In my view, a DMR is a role of more precision, but not a sniper role. So magnification does not need to be very high. An 8x scope is plenty for the role... Some really want more magnification, and if that is the case, 15x is a maximum I would put on anything that is being used inside 600yds. A quality 10x with great glass, forgiving eyebox, and useful reticle is probably the optimal choice for this role... I think an 18in barrel is suitable for the role if you are using 77gr stuff. So you can save a couple inches there.

The enhanced lightweight barrel profiles, like the Gunner, Hanson, and the enhanced lightweight profile from BCM... (Clever name there BCM) Help shed some noticable weight, without sacrificing too much in the way of heat affecting the barrel.

A well made 5.56 chamber can be plenty accurate. My fiance's rifle has a ballisic advantage barrel with a 5.56 chamber, and it shoots the Black hills 77gr stuff into 0.5-0.75moa at 100yds pretty consistently... I have managed multiple groups like that in a row... So long as I am doing my part and I didn't drink too much caffeine, or otherwise have jitters going. That doesn't happen often though, so I tend to get 1-1.25moa most days. That's the key, being steady, calm and not fatigued.


But wanting a handier setup, the recce like setup that you described is a great way to go.

You could put a scope with a bit more magnification on it, and choosing well, you can get one that is fairly light... And then you would have something closer to a DMR rifle. I would say it is good for 450-500yds and still being effective with 77gr stuff. Really I look at 500yds as basically a max for 5.56... just as a general rule of thumb. Extra barrel would help with energy and velocity when out that far though.
marine6680 is online now  
Old August 20, 2018, 05:36 AM   #7
Mobuck
Senior Member
 
Join Date: February 2, 2010
Posts: 6,140
"I am thinking of making a 16" DMR "

So, what's wrong with an off the shelf 16" Hbar? They're a wee bit muzzle heavy but you have to compromise somewhere. I've been using one for 9 or 10 years as my winter EDC carbine and it provides all the accuracy required.

Oh yeah, you said 4x optic. In that case, my 16" Hbar can provide MORE accuracy than most shooters can utilize with 4x.
Mobuck is offline  
Old August 20, 2018, 07:04 AM   #8
Bartholomew Roberts
Senior Member
 
Join Date: June 12, 2000
Location: Texas and Oklahoma area
Posts: 7,594
Originally, the first concept Marine DMRs used stainless match barrels and 4x ACOGs. They eventually went to regular chrome-lined barrels because service life was longer and by and large, most Marines couldn’t outshoot the GI barrel with good ammo anyway.

I’m not really a fan of bipods except when I am trying to shoot tiny groups because they get in the way of a lot of practical shooting. I’ll just monopod the magazine or use something near by for support. But they are handy to have occasionally and you can take it off if you aren’t using it.

I think what you describe will probably outperform most shooters’ abilities. If I were just going with a single optic, I prefer the TA11 3.5x ACOG to the TA31 4x ACOG. I like the bigger exit pupil and eye relief. I also use an offset reddot though, which would pair well with the TA31.
Bartholomew Roberts is offline  
Old August 20, 2018, 08:52 AM   #9
marine6680
Senior Member
 
Join Date: July 24, 2012
Location: Parker, CO
Posts: 4,550
As far as GI barrels... My Colt can shoot 55gr 5.56 spec stuff into 1.5moa without much difficulty when I do my part. It is suprisingly accurate for a basic GI profile carbine gas barrel. I have not tried putting higher quality ammo through it though, it may do a lot better, or gain nothing. As it stands, shooting that well with cheap ammo is good enough for my needs of the rifle.

My FN CHF barrel can do the same thing.

BA and Faxon have made their name by making barrels that are solid performers, usually 1moa with decent ammo, but at a reasonable price point. They nitride the barrels for better service life as well. They may not be the first choice for a true high end precision setup, but they perform well enough to fit the majority of shooters needs or better.

I like the 3.5x ACOG as well, you do gain a little weight and size, and lose some field of view, when compared to the 4x... But you gain longer eye relief and a bit larger exit pupil.

Paired with a offset RDS, it's a good optic with a lot of benefits... And using a mount that brings back the scope farther to the rear, helps the 4x work better for most people.

Last edited by marine6680; August 20, 2018 at 10:43 AM.
marine6680 is online now  
Old August 20, 2018, 09:23 AM   #10
TrueBlue711
Senior Member
 
Join Date: March 16, 2011
Posts: 325
Quote:
I am thinking of making a 16" DMR that would be lighter and handier than the 20" US military DMRs.
I built the same thing. Only difference from your description is the optic (I'll be upgrading mine down the road). I like it a lot, very lightweight. I built it for long walking coyote hunts in the desert initially. Now, I'm turning it into an entry level 3-gun rifle (hence the vertical grip). The only thing I would change is having the gas system as a mid-length instead of a carbine. That being said, I've never had any issues with the carbine gas system.
Attached Images
File Type: jpg ARv1.jpg (53.1 KB, 14 views)
TrueBlue711 is offline  
Old August 20, 2018, 10:43 AM   #11
MarkCO
Senior Member
 
Join Date: October 21, 1998
Location: Colorado, USA
Posts: 2,415
Sounds like you are describing my 3Gun rifle. Stretch16 barrel (optimum gas length, Wylde chamber). AR-Gold trigger, Burris RT-6 optic. I have a section of pic rail on the front for a bi-pod and a RRS Arca rail section on the back of the HG for the tri-pod. I use it in 3Gun, DMR and as the Carbine in Precision matches. I typically shoot 69 grain bullets, and have shot it out to 1K, but usually 750 is all I need.
__________________
Good Shooting, MarkCO
www.CarbonArms.us
MarkCO is offline  
Old September 13, 2018, 09:45 AM   #12
Polinese
Senior Member
 
Join Date: September 27, 2010
Posts: 682
As a couple others have said I would go with a low powered variable scope, especially so you can collect some data on it and figure out the actual adjustments for different ranges vs the "it should be close" BDC of an acog
Polinese is offline  
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -5. The time now is 03:09 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2018, vBulletin Solutions, Inc.
This site and contents, including all posts, Copyright © 1998-2018 S.W.A.T. Magazine
Copyright Complaints: Please direct DMCA Takedown Notices to the registered agent: thefiringline.com
Contact Us
Page generated in 0.06853 seconds with 11 queries