Dpms LR-308 case issues and buffer tube damage.

[Yellowfever440]

I bought this LR-308 from a friend and it has less than a 1000 rounds through it, 400 roughly by me. I was cleaning it tonight and noticed all the Damage on the end of the buffer tube where it screws into the lower frame. I haven't ever noticed it until tonight and i'm curious if anyone has any ideas what is causing this now. its the BCG contacting the end of the buffer tube but i don't know if i misplaced something.

 

[Yellowfever440]

The other question i had was about my cases, when i fire a round and it cycles the brass gets beat up pretty good, i am assuming by the barrel side of the feed ramps. I have some pictures, but its hard to get good pictures to show the dents, the outside of the case neck is dented and gouged, if it was just scratched i wouldn't care too much. I want to make the cases last as long as possible for reloading and saving some money in the long run.

I have run 40 to 41gr IMR 4064 with 168 gr AMAX, 40 gr H4895 with 168 gr AMAX and 40-42 gr varget with 168 AMAX/BTHP. I have also used some fiocchi 150 Gr factory ammo and some remington power point factory ammo. THanks for any advice that anyone can give.

 

[Yondering]

I bought this LR-308 from a friend and it has less than a 1000 rounds through it, 400 roughly by me. I was cleaning it tonight and noticed all the Damage on the end of the buffer tube where it screws into the lower frame. I haven't ever noticed it until tonight and i'm curious if anyone has any ideas what is causing this now. its the BCG contacting the end of the buffer tube but i don't know if i misplaced something.


View attachment 6986987View attachment 6986989View attachment 6986993View attachment 6986995

That looks like it's caused by using a long buffer tube (like PSA style) with a 308 buffer. For a 308, there are two ways to set up the buffer system - long tube and standard AR15 buffer, or standard tube and short 308 buffer. Either works fine, but if you use a short 308 buffer in a long 308 tube, the carrier will bottom out as shown in your pics.

Easiest solution is to swap your buffer for an AR15-length buffer of the same weight, and make sure the carrier doesn't come back that far.

It looks like you've done some permanent damage to your lower receiver and buffer tube because of that setup. However, if you check for and remove any burrs on the buffer tube, that damage shouldn't affect function.

 

[Yondering]

For the case damage issue - some of that is caused by sharp edges on the forward side of the barrel extension lugs (the surface that the bolt lugs seat against). Depending on your skill level with this sort of thing, you can gently remove the sharp edges so they don't cut into the brass. If you extract an empty case from the chamber slowly, you can see which of the lugs make contact and where to remove the sharp edges. You don't have to do all of them, and definitely don't remove very much.

Your rifle may be (translation: probably is) over gassed a bit too, as is common with these rifles. You can try heavier buffers or an adjustable gas block; restricting the gas the correct amount to get the rifle tuned properly makes it shoot smoother as well, which is always a good side benefit.

 

[DRAM40A1]

In this photo, is the buffer and spring still in the buffer tube? I guess it really doesn’t matter because either way, your bolt carrier is obviously going to far to the rear due to the buffer being too short.

 

[Yellowfever440]

Yes the buffer and spring are in the buffer tube in that picture.

This is all factory from dpms, I changed the stock but it is the factory buffer tube, buffer and spring. I will see what I can find for buffers the same weight and longer. Thank you.

What's a good quality adjustable gas block? I have seen a lot about the seekins adjustable block, would that be a good choice?

Would it be worth getting the barrel threaded for a muzzle brake to cut down on some of the recoil or is not worth the money?

 

[XLR308]

If it is indeed all factory then it is factory wrong.
There are some miss matched parts in the buffer and tube assembly.

 

[Yellowfever440]

OK if I push my buffer all the way into the tube with spring it it is 7 inches from the face of the buffer to the opening of the tube. From the back of the bolt to the shoulder is 4.6 inches.



Does everything in the picture look right?

 

[XLR308]

OK if I push my buffer all the way into the tube with spring it it is 7 inches from the face of the buffer to the opening of the tube. From the back of the bolt to the shoulder is 4.6 inches.

View attachment 6987185

Does everything in the picture look right?

Looks to me like you have a carbine buffer in a rifle length tube.

Measure the buffer length and then look up the length required for a rifle length.

A quick search showed 5.285" but verify that through DPMS

 

[ShooterwithNoName]

Yea Seekins, JP, Syrac, all make good adjustable gas blocks along with quite a few others.

Does your rifle have the 24" barrel? If so they are pretty heavy. For the cost of threading the barrel you have, it would probably be better spent going towards a new barrel with features that you want. It's not too big of a deal to thread an AR barrel for a good gunsmith. Depends on what you intend to use the rifle for. If the factory barrel shoots good I wouldnt alter it too much. If not, theres some great barrels out there nowadays for a decent price.

 

[ShooterwithNoName]

Looks to me like you have a carbine buffer in a rifle length tube.

This^^^ you've got a carbine buffer in a rifle length tube. If you had a collapsible stock/length buffer tube then that would be the correct buffer. You can search for a 308 rifle length buffer and get the right one for not much at all. I would possibly go ahead and get a new spring to match so you know it's good to go.

 

[ShooterwithNoName]

Heres a rifle length AR15 buffer "top" compared to a rifle length AR10/308 buffer "bottom".

You'll need the buffer length on the bottom, the black one. That's the buffer for your rifle. My thinking is the buffer may have been swapped at some point because you do have a 308 "carbine" buffer pictured. I would bet that when it was installed that it's possible the wrong spring may have been installed too. That'll make your rifle slam pretty hard while cycling. The correct buffer will no doubt make it shoot smoother, not damage your receiver and may even be a bit better on the brass. Any semi auto is unfortunately hard on brass to some degree.

P.S...
I'm really surprised that it hasn't done more damage than that in +/-1k rounds. Your bolt carrier has been smacking your lower receiver and buffer tube every time it has cycled with that buffer. So in effect, you've never actually had a buffer at all. Just metal to metal contact every round. Hope this helps, good luck with it. I think you'll be ok with a buffer swap. Just check it over for any signs of fracturing on the lower. The buffer tube is easy to change.

 

[Yellowfever440]

The buffer that is in it is only 2.5 inches long so either its factory wrong or it was switched before I bought the gun.

Should this lr308 kick harder than a bolt action 308? I have a 308 ruger precision but it has a muzzle break and it is a lot easier to control than this lr308. I am hoping since it has the wrong buffer maybe it will be a lot more controllable after getting this fixed. Thanks a bunch for all the in put!

 

[XLR308]

Should this lr308 kick harder than a bolt action 308? I have a 308 ruger precision but it has a muzzle break and it is a lot easier to control than this lr308. I am hoping since it has the wrong buffer maybe it will be a lot more controllable after getting this fixed. Thanks a bunch for all the in put!

The Ruger I'm pretty sure is a heavier rifle and has a muzzle break with no feel of the reciprocating mass from the carrier.
But yes not having you carrier slamming into the back of your lower receiver should make a noticeable difference in felt recoil.

 

[Yondering]

The buffer that is in it is only 2.5 inches long so either its factory wrong or it was switched before I bought the gun.

Should this lr308 kick harder than a bolt action 308? I have a 308 ruger precision but it has a muzzle break and it is a lot easier to control than this lr308. I am hoping since it has the wrong buffer maybe it will be a lot more controllable after getting this fixed. Thanks a bunch for all the in put!

Did you (or someone else) install that stock and replace the factory carbine buffer tube with a rifle tube? That seems to be the most likely scenario here.

You definitely need a rifle buffer and spring for that; can't mix and match buffers and tubes.

 

[Yellowfever440]

That is probably what happened. A few months ago I was looking into an adjustable gas block and threading the barrel and putting on a muzzle brake to reduce the recoil and make it a friendlier rifle. While I was doing that someone told me possibly a different buffer could help and I decided not to do any of it. Now that I am learning a lot more about this rifle I am pretty excited to get that swapped and start shooting it some more. I may even put the A2 stock back on it and move this prs to my rpm now.

 

[DRAM40A1]

If it originally had an A2 stock, then it would have had a rifle buffer and spring. The one in the photo is definitely a carbine buffer. Something doesn’t make sense. The fact that you bought it from a friend kind of explains. Maybe your friend put the carbine buffer in it, or it was originally a collapsible stock?

 

[ShooterwithNoName]

I would say that swapping out that buffer is gonna make it have a much better recoil impulse. 308 ARs are great, parts interchangeability can be finicky but they are one of my favorite rifles to shoot.

I love the good old A2 stock. I've ran A2 stocks since I purchased my first AR. The PRS is a great stock, I just am comfortable with the A2. High Power has a lot to do with that.

But your on the right track. Things like this are how we all learn about these rifles. It sucks when stuff goes wrong but the more you know about the rifle the more confident you'll be with it.

 

[Yellowfever440]

I was looking over adjustable gas blocks for this LR 308 I'm having trouble with a d I see there are clamp on and set screw styles, is one design better than the other? The one that is on the rifle now is a set screw style.

PS - Also I did find out the gun came with a 6 position stock and it was switched to an A2 buttstock before I bought it. So the buffer assembly was over looked. I am going to get the right buffer and spring for it. Honestly I cant wait because I'm hoping it will be like buying a new gun for 50 or 60 bucks!

 

[DRAM40A1]

I prefer the clamp on blocks. Superlative makes a great one. Just make sure you install a 308 Rifle buffer and spring. Search heavybuffer.com
There are many benefits to running a heavier than factory buffer on a large frame AR. You are on the right track.

 

[Yellowfever440]

I ordered the dpms rifle buffer, rifle buffer spring and rifle buffer tube from midwayusa.com for now. Just having the right stuff will probably help out alot, the buffer that heavybuffers.com shows for a .308 is $125 bucks, does anyone else have one and is it worth it?

 

[DRAM40A1]

KAK has one for $65. A heavier buffer will keep the bolt locked up a little longer, allowing the pressure to reduce before extraction. I’ve read it will also reduce recoil. I have one of Clint’s XC Carbine buffer and spring. It was $140 and worth every penny.

 

[ShooterwithNoName]

Agreed with DRAM40A1, I have had much better luck with clamp on gas blocks. Also I believe the heavy buffer is worth it. Especially if your going to shoot long range with it, it helped the recoil impulse with my follow up shots. Also helps you spot through the scope if you can.

I put the JP captured buffer spring set up in my long range 308 AR. On my carbine I run a heavy carbine length buffer. Glad you got it sorted out. I believe that will make a good difference in your rifle. Bound to be better recoil.

 

[bfoosh006]

Now that your .308 BCG isn't slamming into your lower receiver extension.. you see a noticeable difference from that alone.

And before I forget... you might wait on ordering parts, there may be Christmas sales.

I also recommend the KAK .308 rifle length buffer, for your rifle length buffer tube.

I prefer the "dead blow" sliding weight buffers.

As for Adj. GB's ... I use SLR's Super easy to tune and use.

As others have mentioned, your brass marks are from the feed ramp lugs.... a quick deburring / polishing with a Dremel felt cone and polish will help a lot.

BE SURE to thoroughly clean the fuzz and polish from the chamber and lugs ... PRIOR to allowing the bolt lock closed.
The fuzz can get between the bolt and lugs... and lock it up pretty tight.

 

[Yondering]

I like Seekins' gas block; easy to use and never had any issues with them. They are a set screw style.

 

[Yellowfever440]

Just an update for those that handed me some free advice. I got my standard DPMS LR-308 rifle length buffer, spring and tube Friday and put them in and shot Sunday. The old spring and buffer were definitely wrong and the gun is more accurate and a lot more fun to shoot. Thanks for all the help, i am going to keep reloading and get an adjustable gas block just so I can slow the action down some but the recoil is a lot more manageable now. Its also not as hard on the brass, i'm assuming its because the bolt is staying locked a fraction longer from the buffer weight and the heavier spring is slowing it down some. I only wish i would of caught it sooner.

 

[ShooterwithNoName]

Good deal yellowfever440. Glad you got it running again. Happy shooting and Merry Christmas.

 

[bfoosh006]

Glad to hear you have a fun firearm now.

After you install an Adj. GB ... you will be even more surprised.

Following your train of thought about leaving the bolt locked slightly more milliseconds ( slower cyclic speed , just by milliseconds )

The firearm will be easier on everything, you, the parts, the brass, and follow up shoots will be far easier.

BTW, make sure your bolt over travel isn't excessive... best limited to about 3/16"... use the 25 cent quarter trick if needed.

 

[Yellowfever440]

BTW, make sure your bolt over travel isn't excessive... best limited to about 3/16"... use the 25 cent quarter trick if needed.

I guess I don't know what this means? I will have to research this a little bit.

 

[bfoosh006]

Your BCG shouldn't extend past the bolt catch ( When fully depressed into the buffer tube, and not via the CH ) more then about 3/16" ... excess space can cause unwanted smacking on the bolt catch.

A common way to adjust the BCG over travel is to use 25 cent US quarters in the bottom of the buffer tube as spacers. I have spacers in numerous AR platforms to limit the overtravel of the BCG. ... and limits the amount of momentum a BCG can create, and then dump onto the bolt catch.

 

[DRAM40A1]

I have a POF that the bolt carrier group was hanging up at the rear. I read about adjusting the overtravel and after putting two quarters in the back, the issue is resolved.