Looking for information. I just ordered the parts to complete a DPMS pattern AR308. This is actually the second stage of completing my skirmish rifle project from last year. If you don’t need to read the entire thing, scroll down to the last paragraph for my question. If you are a gun nerd who likes to tinker, read on:

For those who aren’t familiar with the build, I did the upper last year. I took a DPMS Oracle and reworked the upper. I put a new barrel, BCG, and forend on the rifle. I did this because parts were hard to come by at the time, and I did what I could with the parts that I could find.

I reworked it by replacing the 16 inch heavy barrel that came with the rifle with an 18 inch Faxon pencil barrel. Then I added an EDGE 15 inch Carbon Fiber handguard from Brigand Arms, an adjustable gas block, a Nitromet gas tube, and a Gemtech compensator. I also replaced the bolt carrier with a low mass bolt carrier from JP rifles. At the time, JP didn’t have any bolts. They do now, so we will go ahead with that.

I decided to go all out and build my dream AR308. So this is what I have come up with so far:

The upper

Total cost for the completed upper was just over $1400, and I completed it back in December. (I had to add a couple of things so that I could reassemble my Oracle. When I am done, I will have 2 AR rifles in 308). The next part of the project will be building a lower receiver.

The lower

I began this build by buying a Freedom Kit from 5D tactical. The whole kit costs $584. The majority of that cost covers the jig and tools needed to complete the two 80 percent lowers that are part of the kit. That also means that I get a 223 lower to practice on before I do the 308 one. I am only going to count $140 of the cost of the kit against the cost of this rifle.

I have no relationship with any of the vendors or manufacturers mentioned in this post, other than me being a customer. The prices paid and any discounts I received were those available to the general public.

Here is my information request. I am looking for recommendations for two important parts. I am looking for recommendations for a drop in trigger and a buffer assembly. For the buffer, I am thinking either a captured spring buffer like this one, or a hydraulic buffer like this one. What do you my readers think?

Categories: Guns


it's just Boris · July 7, 2021 at 7:16 pm

Trigger: I’m quite fond of Elftmann for drop-ins. (Or, if you want a two-stage, and don’t mind dealing with a standard install, it’s really hard to beat the LaRue MBT’s value and trigger pull quality.)

Buffer assembly: I’ve not used the JP captured spring, but have had good luck with Armaspec. Those are my preferred buffer assembly these days. I’ve never tried a hydraulic buffer so can’t comment.

Chris · July 7, 2021 at 8:09 pm

Larue MBT trigger. Its a geissele at
Half the price. Seriously! Got about 15 of them.

Buffer- i stick with standard stuff, so i can pilfer it off others gear, should that time arise.
Other than that…in my 556’s, i always run the heaviest Buffers that the gun will run reliabliy with. H3. I know this doesnt apply to 308, my point run the heaviest you can as ling as the gun runs 100%.

Thats my BS.
Good luck

Porkypine · July 7, 2021 at 9:16 pm

Trigger: Larue MBT.
Or they make a straight bow if that’s your preferred flavor.

Buffer: I have a couple of different flavors of captured spring buffers installed but the JP Enterprise Gen 1 are my favorites. I have no experience with their Gen 2 system (or with hydraulic buffers) but if it’s an improvement in their original then you won’t be disappointed.

Sarin · July 7, 2021 at 10:28 pm

Cant speak to the buffers at all.

Triggers, on the other hand…

Jamesmadisontactical.com makes a fair single stage drop-in trigger. Have a few friends that swear by them.

Risearmament.com offer several models of drop-in trigger. I have an older model. Was pleasantly surprised. All single stage as far as I know.

Elftmann are great triggers. My pops has one. Love shooting with it. Believe they have two-stage available as well.

Timney makes a rock-solid product. Was a huge improvement for me. They even have adjustable versions where you can change the trigger pull weight, within a finite range. Only reason I got the rise armament one is because there were no timney or elftmann in stock when I bought most recently.

CMCtriggers.com offer both single and two-stage drop ins. They were the first to market it. They can be finnickey, particularly with 80% lowers if you’re not perfectly machined to depth. With the 5D jig, you should be fine.

Hope this helps.

Russell G. · July 8, 2021 at 7:06 am

I’ve never completely understood the adjustable gas block/buffer spring fascination and tweeking. I think it is more of an urban legend than anything else. If the brass is exiting reliably at the 4-5 o’clock position, leave it alone. Primer strike patterns (on SA) also tell you very reliable information about the timing with the gas system. The number of “flyers” on your groups also tell you about the pressures/timing in that barrel. Learn to read your primers when you pick up the brass.

    it's just Boris · July 8, 2021 at 9:01 am

    Three reasons come to mind, beyond than liking to tinker. (Which is also a good reason imo…)

    One, a suppressor can cause noticeably increased back pressure, leading to harsher cycling, and a face full of combusted propellant. The agb lets you dial that down to a great extent for when the suppressor is on the rifle, and back to normal when it’s off.

    Two, if you move away from a standard round for the AR, e.g. 6.5 Grendel or 7.62×39, the agb can help you compensate for the different pressure and volume of gas generated, e.g. to reduce cycling harshness and felt recoil while remaining reliable. It also lets you “fix” a barrel with too big of a gas port, although in that case one might be better served by getting a better barrel.

    Three, if you standardize on a particular load, mucking with the agb and buffer can let you tune for reliable operation with as low a recoil as possible. For those of us with recoil sensitive spouses this is a bonus.

    All three of these are more relevant when moving to a .308 sized AR platform, in my limited experience, compared to an AR-15 in 5.56×45.

      Divemedic · July 8, 2021 at 9:10 am

      A big part of it for me is that the first version of this build only weighs 8 pounds. As a 308, this lightweight of a rifle and a day at the range leaves me with visible bruises on my right shoulder. I am trying to minimize recoil and maintain a lightweight rifle.

Ben · July 8, 2021 at 11:03 am

Another endorsement for the LaRue MBT trigger. I love mine and the value can’t be beat.

They were over $200 when they first came out and over the years LaRue has improved the quality and reduced the price to well under $100.

Big Country Expat · July 8, 2021 at 9:23 pm

Yeah bro… that BCG… Holy Hells that is insanely light. STILL Blows my mind how light it is/was.

Now, FYI: The Kyntec hydro-buffer.

Two words: Buy. It.

If you followed the build I did for my reader, he reported back that his ole Lady (whom the rifle was built for) positively LOVES the thing. The Hydraulic Buffer is purely da bomb.

Cuts the felt recoil by at least 40%. His wife who I designed it for, is an ‘itty bitty’ gurlie-gurl. 5 foot nuthin’, small chicka… she has NO Issue throwing through with the Kyntec I installed. WISH I could get an endorsement deal with them, but no luck so far.

10/10, buy it. shoot it. love it.

Nice Buck · July 8, 2021 at 10:03 pm

Bought Larue MBT2 2 stage trigger on Kenny Lanes recommendation. 2.5 pound take up pull to stop, then 2 pound pull to fire. It will fit LR-308 or AR-15. It is a nice trigger.

D.C. · July 10, 2021 at 10:50 am

These guys, https://www.sprinco.com/index.html are buffer spring specialists. They produced a fantastic tuning guide here: https://www.sprinco.com/SPRINCO-DOCS/Horizontal%20Case%20Ejection%20Trajectory%20Chart.pdf
It is off this page: https://www.sprinco.com/ar-buffer.html

I can tell you my results are very well worth the work, which is pretty simple once you grasp the nuts & bolts of their recommendations for tuning based on the way the impingement system functions. RTalk about variables and technical unknown unknowns!
I learned a great deal about my AR platforms and can not state enough how much improved my weapons are going this route.
It stands to reason once I had lovingly invested so much is such a fine small unit infantry combat rifle, refining, then capitalizing on Stoner’s genius and all the awesome proven combat grade accruements to the max. Seems my 300BLK rifles especially require this fine tuning. I have managed to get a 10.5 inch bbl AR15 in 300BLK to function with both super 110 gran and 190-200 grain subs, sans a can. You can balance out the spring/gas/mass ratio that fine, its in the AR gas impingement design, just have to go in after it.
Oh yeah, using JP Rifles spiral lock gas ring, helped considerably in the refinement/balance regardless of caliber or which AR, 15 or 10. I think it is due to their low friction and improved gas sealing, eliminates another variable.
Tried out Sprinco’s machine gunner lube, it’s an improvement over my previous preferred lubes, now I’m using it on everything, even my dryer and out in the shop. Its really effective on my EDC XDe .45 pistola, which I had to strip and completely clean the persperation on it from ITW carry, which was just beginning to produce signs of corrosion from the constant moisture. Thats no longer a problem it was. I the slides and bolts have this nice slick glide feel to them, especially right at the last lock-unlock points in the lock up sequence.
That seems highly critical on the XDe and XDA 45’s. The XD Service I got in 2004 when they first came out has over 3000 rds thru it at Max Velocitiy’s combat handgun courses, I thought it was nicely broke in, till putting the MGL on it, now its lock/unlock transitions seem seamless, like hot butter on a teflon pan. Slickety slick man!
All in all these Sprinco guys offer a superlative group of bits and methods, for such an inexpensive upgrading of my weapons. The AR’s shoot so much smoother, its like another realm, subtle, but the diff’s are amazing.
Did a similar DPMS in .308, used a Green Mountain Rifle Barrel chambered blank, in fact all my AR’s have them, in 300, 556 and 7.62, it’s pretty basic gun smithing machining, and they give you the ability to configure all of the external aspects of the barrels way you like. Here is their page: https://www.gmriflebarrel.com/ar15-barrel-blanks/
Been producing my own TC Contender barrels using GMRB blanks, and I have to say they got some kind of accuracy process in their shop, thats enabling me to make barrels with accuracy thats so far past my shooting skills I have no words to define it. On the 308 DPMS, I was totally nonplussed when I first tested it. I did not know what an accurate rifle was before that, my old welder eyes limit my potential, but this instance is a game changer over anything previous.
I think a lot of whats going on is due to tuning the buffer/gas system via this Sprinco tuning process on the 308, maybe because everything has considerably more mass and forces than the little brother AR. Not running any muzzle device on it, a thread protector, and an as machined 11 degree muzzle crown, the recoil impulse is a long shove, gentle. I built a Saiga 308, 16 inch barrel, its what I gauge all other 308’s by, because its got a very gentle recoil, probably it’s due to the lock/unlock sequence time in the bolt and the long stroke piston to bolt carrier mass. The DPMS is even gentler. Not that SAMMI .308 ammo is a recoil beast. But the sight recovery sequence is non existent with basic firm rifle handling.
Every bit helps, and its the little things sometimes which really do add up, and if one is going to the effort to build in the best features and customization, refining things is not much more work or expense, is what I’m saying I have experienced.
I lurked for a couple years before trying out Sprinco’s system of tuning. To me, now its what I do regardless, as a matter of course.

Oh, I should mention I am partial to an A1 Rifle length stock and buffer setup, all AR’s set up the same, same pull, stock, grip, and trigger on all.
After all, my mindset is these are life protecting weapons, combat weapons first.

I chose, after going thru MV combat courses, and becoming wiser from all the great people out there with their phenomenal efforts of helping us “every citizen a soldier”, in the small unit infantry combat tactics for the citizen cannon, to simply go the best of mil spec with the ingenious M4 combat carbine survival kit/upgrade stuff resulting from the last 30 or so years, like GMRB’s high vanadium alloy, developed to rectify the barrel bursting issue at the gas block section from over heating during necessary high rates of semi auto fire in extreme combat conditions, and their development of 9130 for the bolt head, which the dot mil PTB rejected, but went on to eventually be a high standard for those in the know. Things like this became my philosophy, particularly after seeing how others rifles stood up in live sustained fire combat courses, and listening to what Max shared from his personal observations. I chose to take these elements to heart and apply them to my weapons, and I am entirely happy with the outcome.

I believe also we all when feasible, must become our own fabricators of rifles, it is the holistic thing, just as combat training in SUT and the mindset is, it completes the every citizen a soldier, a warrior, circle, it is to a nth degree the virtue of prudence lived, it is the sustainable warrior thing to I believe.
After everything, at the crux, there is a center to our great history as Freemen armed to the fucking teeth, and it is the Rifle.

So pieces like your post here DM are part of a renaissance. Our colonial era brothers in arms, they where remarkable makers, take a gander at these dudes on this blog, great photography, these folks are revining that industrial artistry and creativity from that era, the arms and other art and the craftsmanship these people are producing are stunning. Inspiring is an understatement.

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