DPMS LR-308 Accuracy Questions


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Joe Link
August 24, 2008, 03:19 PM
I'd like to get a couple AR's before the election (true concern or not, it's a great excuse!) and I'm thinking of picking up a DPMS LR-308 with the 24" barrel and hopefully building it for 1000+ yard stuff. I've read these rifles are sub-MOA out of the box, but I'm curious to know if they have the potential to have comparable accuracy to a bolt action rifle. I ask this because I've also been thinking of building a bolt action rifle and it'd be really nice if one of these could do it all, especially considering that for the price I could get an M4 and a cheap AK.

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W.E.G.
August 24, 2008, 03:27 PM
five shots @ 100 yards last week from LR-308-T (16" barrel)
only mod is a Rock River two-stage trigger
otherwise bone-stock

optic is Leupold VX-II 3x9

Lake City M852 ammo

not a cherry-picked group
only group I shot with this ammo

http://i227.photobucket.com/albums/dd7/rkba2da/targets/2008-08-18%20-%20DPMS/M852smaller.jpg

Group with Federal Gold Medal was a bit bigger.

http://i227.photobucket.com/albums/dd7/rkba2da/targets/2008-08-18%20-%20DPMS/FederalGoldMedal.jpg

Joe Link
August 24, 2008, 03:31 PM
Thanks for the reply :D

I also meant to ask, what's the difference in accuracy between the 16" and 24" barrels?

CBS220
August 24, 2008, 04:43 PM
No appreciable difference and in theory a shorter barrel may be more accurate due to a greater stiffness if the barrels are of equal weight.

However, personally, I do a lot of shooting from a stand or bench, so I always take the heaviest, longest barreled thing I can get for anything other than social work!

matrem
August 24, 2008, 04:44 PM
With "equal" bbl quality,the 16" will not be any disadvantage for"pure" accuracy,however the 16" is a disadvantage in "long range"(400 yds or more-bullet velocity).
It's been my experience that bolts can be "made" a bit more accurate at extreme ranges,IMO that's due to the advantages of "specific rifle" steps that one can do while loading for a bolt,(bullet seating,bolt face,neck sizing).
Don't know what your idea of "accuracy" is,but the Panther 24" .308 that I had the privelege to shoot ("tested") last week put 10 handloads into about 5/8 " at 105 yds.That is excellent IMO.

TRGRHPY
August 24, 2008, 08:38 PM
I have a DPMS .308 with a cryo'd and fluted 24" barrel. I went through a 200rd break-in (no measured groups) and started measuring groups after that. with 140 rds post break-in, I have an average of .74 MOA, all shot at 200 yards. The best 3 round group was .186 MOA and the best (of only two) five rd group of .65 MOA. I tried a few different rounds and settled on the Fed Gold Match 168gr since then. I haven't tried the 175gr yet, although at 200yds I'm not sure that there would be much of a difference. I need to make a friend in the Colorado Springs area who belongs to a club or has access to a longer range.. :)


The information that I have gathered from other DPMS .308 owners is that they all claim sub-MOA. If you add in a few that might have a liberal ruler, I still figure that it is at least an moa rifle, even though DPMS makes no claim or gaurantee of accuracy (that I know of).

It is my understanding, as far as barrel length for the .308 goes, is that you can have good accuracy at short ranges with a 16", but that the .308 needs about 20" to burn completely. So barrels with 20-22" fare better at longer ranges due to the increased pressure. I have also read and seen that a 24" barrel doesn't have any real increase in accuracy or pressure over a 20-22". If you notice, the SASS uses a 20", but whether it has to do with what I understand or if it just has to do with the benefits of a shorter barrel, I don't know. It could be a combination of the two, that the benefit of the additional 4" is not enough to warrant the extra length and weight. I'm open for comments about this, of course. I guess that your intended purpose will determine the barrel length. I wouldn't take what I said as gospel, it's just what I have read and seen (articles, comparisons, shooting time, etc.).

I am not sure if the .308 is good for anything much beyond 1000, perhaps better for 1000 and under. IIRC, with factory ammo, 1000yds is possible but 800 yds is about the limit.

BammaYankee
August 25, 2008, 12:26 AM
"800 yards is about the limit" (with factory ammo).

I use Black Hills factory 175s at 1000 using a 21" tube... Never had any problem reaching the target...

TRGRHPY
August 25, 2008, 05:26 PM
Are you using a bolt or auto-loader?

I haven't had to opportunity to shoot it longer than the 200 yds that I mentioned, but when I asked others at the range and shop about it I was told that 1000 would be pushing it, but could/can be done with factory ammo. It was suggested that I research to find a load combination specifically for the range(s) I intended to shoot. I wasn't saying that it can't be done, because I still plan on shooting that distance as a goal, but that with factory ammo at 1000+yds there is possibly a better selection other than the .308. Yes? No? I'm curious...I'm like Obama, I'm open to changing my mind no matter what, and probably will multiple times before it's all said and done...:D

velocette
August 25, 2008, 06:47 PM
My LR 308 B with an 18" cryo barrel is constently sub MOA with my handloads and with Federal Power shok 150 gr ammo (the cheapest 308 ammo at Wal Mart, go figure) Using 41 gr of 4895 or 42 gr of RL 15 & Sierra 168 gr HPBT match bullets it averages .68" 5 round groups. The Fed factory ammo averages .88"
These groups are from a bench using a bipod and my Mk1 mod 1 shoulder. No bags.
The rifle has been absolutely reliable through around 1100 rds of all different reloads and factory ammo. (no milsurp stuff)
Was it expensive? yes, was it worth it? You bet!


Roger

Joe Link
August 26, 2008, 03:03 PM
Thanks for the tips guys, I'm really tempted to pick one of these up.

TRGRHPY
August 27, 2008, 12:26 PM
Good luck with your purchase! Hope everything goes well (good dealer, good price, etc.) and I'm confident that you will not be dissapointed.

Justice5
February 5, 2009, 09:50 PM
Hello. I'm brand new to this sight, but you all seem to have better knowledge about the DPMS SASS than anywhere else I have checked. We currently have 4 new of these issued to our sniper team. I have approximately 190 rounds through mine personally. For some reason, none of the 4 of us are meeting our MOA requirements at 100 yards yet. We currently shoot the Federal Match Grade HP ammo, 68 grain. Very good quality ammo and is well under MOA with our older bolt rifles. Our 4 shot groups are under 2" at 100 yards, but that does not meet our requirements for qualification. We have to be MOA, obviously under 1 inch.

Any suggestions? We have new ammo on order that we plan to try out for accuracy purposes. We have followed the break in suggestions exactly as DPMS required. I like to believe that all 4 of us are decent shots based on our past experience and results.

Sorry to just jump in here and start asking for stuff, but I'm near the point of returning this rifle if it doesn't get much better. I love the rifle and it meets our needs otherwise.

Thanks in advance for any advice.

taliv
February 5, 2009, 10:15 PM
welcome to THR!

I'm a little surprised at those results. DPMS has a reputation for accurate rifles.

I assume you mean 168g Fed Gold Medal Match? That's excellent ammo.

Are you shooting from a bench? bipod? bags? did you change out the stocks? What scope/rings? Groups round or mostly horizontal or mostly vertical?

breakin shouldn't be a big deal.

Javelin
February 5, 2009, 10:26 PM
DPMS seriously makes some accurate .308 AR platforms.

Check out the DPMS SASS. It is an 18" fluted barrel that will also do sub-moa all day on a bet and is a great gun with accuracy up to 800 meters. You could shoot farther but your sub-sonic past that point.

:)

Justice5
February 6, 2009, 05:15 AM
Taliv, thank you first of all for the fast response. Sorry, I was typing so fast I forgot the 1 in front of 68 grain. Yes, that is the correct ammo. It's our current duty ammo for open air rounds right now, but we may change it.
Shooting from prone, using bipod with a bean bag rear support, since we started making adjustments after some break in time. Fairly solid position and what we use in the field as well for the most part. Our scopes are Leopold Mk4, 4.5-14X50mm with illuminate reticles. During our break in period, we mainly shot from a bench with bipod and bags for the purpose of getting it over with since it was easier to clean this way. I love the scope. If it helps diagonose this issue, it seems that our clean cold barrel shot continues to be different each time. We continually have to make adjustment, typically very minor one's though. I'm talking like 2 or so clicks. As far as the grouping goes, I have noticed that most of my followup shots are about an inch low and a bit to the right. I can't remember exactly what the other guys rounds were doing, but they had very similar accuracy. Seems to be mostly vertical though. Just not staying in the MOA range. We did not change out the stocks, they are all custom from factory. The only add on is the scope. I'm sorry, but I don't know what scope rings we have on them, and I don't have it here at home with me to check. I believe they were purchased with the scope itself, but I'm not positive on that. One of the guys adjusted the slack in the trigger, but that has been about it. I have read so many great accuracy claims with this rifle, and I'm beginning to think that maybe I just need more practice!:) I'm also thinking that maybe a different round would give better results, but it sounds like this rifle has been shooting cheap ammo with amazing results too. Thanks again for your help.

Lloyd Smale
February 6, 2009, 07:24 AM
now im no expert on rifle shooting and if your a sniper you probably allready have forgot more then i know but i relate it to handgun shooting. First shot out of a 1911 in many gun will tend to shoot to a slightly differnt point. Most attribute this to the fact that when you manualy release a slide it is going forward with less ump then if it was returning to battery from a shot. Another thing that can cause it is a mag. If you are shooting your groups with a full mag try loading a couple less to start with and see if it cures the problem and if it does try switching mags. Even feed ramps could possibly cause it. One more thing to keep in mind that some rifles and ar platforms are notorious for this will not settle in and shoot there best groups till theres about 500 rounds down the barrel. Sometimes the difference can be pretty drastic. So dont give up to quickly on those guns.

taliv
February 6, 2009, 09:47 AM
Justice, so are you saying once the gun is warmed up and fouled you can keep 4 or 5 rounds in an MOA? (I have heard bad guys don't wait around for you to take sighter shots :) )
I mean, it's really only the first shot that's bothering you?

Justice5
February 6, 2009, 07:10 PM
Taliv. Both issues are bothering us. I actually wish I was smart enough to photo my target and attach it to this to show you. I didn't keep it anyway since it was a "practice qual".

We shoot a single clean cold barrel, that must be within a 1" circle. The next 4 shots are at a different circle, these 4 are the MOA shots. Our first clean cold is typically very close to bullseye, like I said before a few clicks here and there, but the adjustment never stays the same. It's almost like it's just not consistent. It's high the first time, then low the next clean cold barrel, and so on. That's of course after cleaning it each time before the shot.

The next 4 MOA shots are not within 1" and are typically in a vertical pattern, mine low and to the right it seems. These shots have all been from 100 yards.

We don't necessarily care if the 4 MOA shots are right on bullseye, but we obviously need them to be MOA. I have two 19 round magazines and swap between them. To answer Lloyd Smale regarding the mags, we only load the mags to the amount of rounds that we are shooting that particular string of fire, like 5 rounds in the mag at maximum. I have had a few feeding problems with one magazine, but the other has worked fine. It sometimes jams the round after I use the slide release to close slide, but I'm ordering another magazine to fix that.

I have heard of some sandpaper rounds that help smooth the barrel and possibly improve accuracy, but that just sounds to me like there is no going back after you do that. It's a department gun as well, so there are the warranty issues of course. I'm going to the range again tomorrow to keep trying. The temperature here has been right around freezing level when we have shot, elevation from 400-800 ft. I know none of that makes much difference at 100 yards for sight adjustment though. Thanks guys.

Justice5
February 6, 2009, 07:12 PM
Taliv, sorry but I don't think I answered your question very well. No, even once the gun is warmed up, it still is not within MOA.

taliv
February 6, 2009, 07:36 PM
hmm....


when you said SASS earlier, did you specifically mean exactly this gun http://www.dpmsinc.com/firearms/firearm.aspx?id=19 or one that had been configured similarly? i.e. i assume free floated barrel, etc..


one thing i would try is switching ammo, as was mentioned earlier. perhaps try some hornady tap.

another thing i would try is shoot longer range. move back to 200 or maybe 300-600 yrds. i know it sounds crazy, but try it if you can. i have this issue myself with one theory but no real satisfactory explanation, where i shoot the same sized groups at 100, 200, and not much bigger at 400 with my 6mmXC. e.g. an inch and a quarter at 100 and an inch and a quarter at 200. I've got a 308 rifle that shoots the same way, only slightly bigger groups. (i know, right? maybe it's just me)

if you find your gun doing this, just shoot your qual at 200 and that'll give you your sub-MOA :)

another thing to try is shooting off bags instead of the bipod. maybe it's not tightened properly or something?

another thing to try is your position. when prone, are you laying straight behind the gun like this?
http://www.odcmp.org/0208/images/USAMU_Prone1Img/Open_s.jpg

or at an angle behind the gun like this?
http://www.odcmp.org/0208/images/USAMU_Prone1Img/Bent_s.jpg

1858rem
February 6, 2009, 07:43 PM
hey taliv, try backing the magnification off at 100 yds if you are using a scope, sometimes it helps at closer ranges

Justice5
February 6, 2009, 10:54 PM
Taliv. I clicked your link to DPMS and yes, exactly that gun. Everything came stock from DPMS. We put on our own scope though, listed earlier. I will surely be trying some more ammo, we are likely going with some type of TAP or other bonded round, especially for barrier shooting. We are still trying different types out, but perhaps we will find one that give us sub MOA grouping. I have not shot it past the 100 yet, again for ease of just getting the rounds through it to break it in. I will try the longer shots tomorrow when I go. Our range only lets us shoot up to 300 yds though. That makes sense though, If it's still under 2" at 200 yards, it's within MOA. I like your thinking. As far as your photo posted regarding positions, I personally lay straight back from the rifle, like your top photo. Wide leg spread and all. I know one of the other snipers does the angle position, but I just don't find it to be as solid or as comfy. I was so used to a 10X scope on my previous rifle, and now that I have a 14X, perhaps that is messing me up. I will back it up to 10X next time and see it that helps. You guys have some great suggestions, I appreciate it. I will let you know my results tomorrow, or the next day after I shoot.

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