9mm AR Upgrades Part 2

While I recently spent a lot of time and money upgrading my multi-gun competition rifle to a high standard, I didn’t forget about my competition PCC. Whenever I go out and shoot Steel Challenge, I like to do the “two guns” thing and shoot both a PCC and a pistol. I figure most of my investment is time, and I may as well shoot as much as possible while I’m at the match.

The experience with my competition PCC hasn’t been smooth. In fact, I’d probably say it has been the most finicky ARs I’ve ever built. I spent a lot of time just getting my basic functionality working, and then I later had a very unfortunate catastrophic failure when a bullet got stuck in the rifling during manual extraction. But I persevered through those problems, and wound up with a reliable, accurate PCC. Now I’m on the next step: increasing performance.

When Taccom announced their Delayed Blowback Recoil System (DBRS) a couple years ago, I was intrigued, and to be honest, a little skeptical. Using magnets to delay bolt movement sounded hard to believe. But I saw some positive reviews of it, and decided to give it a try, in conjunction with Taccom’s Extreme Short Stroke Bolt (ESSB).

Disclaimers: I paid full price for the ESSB+DBRS. In fact, as you can see from the article, I actually probably overpaid given that I swapped a $160 part for a $95 part in the end and never received a refund for the difference. So, if anything, expect me to be a little tough on Taccom.

Before I go further, I just want to do terminology clarification. Traditional blowback 9mm ARs (“AR-9”) don’t have a “bolt carrier group” – they have a bolt. There’s no bolt carrier for unlocking the bolt, they’re a single piece. Traditional AR-15s have the bolt carrier group, because the bolt carrier and bolt are separate pieces.

My starting platform was my competition AR-9 with a DDLES 9mm Glock mag lower, an ALG Defense ACT trigger group, an upper receiver of some make I forget, and a 14.5″ JP Supermatch barrel w/ JP tactical comp/brake.

I started off by installing a Hiperfire Hipertouch “Blue Line” trigger, which is their Hipertouch Competition trigger with a blue shoe. Dvor had these on sale at a considerable discount over the street price of a regular Hipertouch Competition trigger. I really liked the Hipertouch ECL in my multi-gun rifle, so I figured that something very similar but a bit cheaper would be just what I was looking for for a PCC.

My order came pretty quickly. Taccom packages their stuff austerely; the ESSB and DBRS came in simple clear bags with instructions.

I started installation with the DBRS. The DBRS requires you to remove your buffer detent pin and spring, so you’re going to be removing the entire buffer tube assembly, at least partially. I took advantage of that to put in a different buffer plate (Magpul ASAP), so there was a little bit of upside to me personally. However, if you staked your buffer tube assembly, you could find this whole process to be a bit annoying. YMMV, etc.

Picture stolen from Taccom. You can see the brass sleeve on the right hand side; this faces the bolt carrier.

Once you’ve gotten the detent and spring out of your lower, you just put the DBRS into the tube, like any other captured spring buffer system. There is a bit of an art to how far you screw in the tube; you want a little bit of the brass section up front showing so that you know the DBRS is making full constant contact with your bolt, but if you screw it too far in, your receivers won’t fit together. Luckily, this happened for me naturally, so I didn’t have to do any further fitting.

The first thing you notice with the DBRS in your gun is that racking the charging handle becomes MUCH more difficult. Unlike a standard AR-15 where pulling the charging handle pulls the bolt carrier back and naturally unlocks the bolt, you are fighting that magnetic delay system to open the action up when you’ve got the DBRS installed. I would recommend a stout charging handle to put up with the extra resistance from racking it back forcefully.

The DBRS works by incorporating rare earth magnets into the recoil system. When you fire a round, the action stays closed (mostly) until it can overcome the force of the magnets, instead of trying to overcome the additional inertia of a heavy bolt and buffer in most straight blowback AR-9s. This gives you a lighter gun that has less moving mass during recoil, which means less sight picture bounce.

In order for the system to work correctly, you need to lighten your 9mm bolt. AR-9 bolts typically have a weight pinned into the back with a roll pin. You have to get that weight out. Since I wanted to have a fallback plan in case this setup didn’t work out, I ordered Taccom’s ESSB and used that for my bolt.

The ESSB is similar, but different, to your usual AR-9 bolt. It has the following features that differentiate it:

  • Milled cross slot for bolt hold open functionality (which most short stroke systems don’t provide)
  • AR-15 style extractor instead of the 1911 style. (Taccom’s not the only one with this feature, but if you have an older AR-9 that does not have it, I’d suggest a bolt upgrade. It’s awesome.)
  • Orientation key instead of a gas key (less weight, more reliability)
  • Nickel boron coating.
  • More dwell time on the disconnector (which reduces doubling from hammer fall problems)

Just to be clear, if you have a newer high quality bolt with a removable weight and AR-15-style extractor, you probably don’t need Taccom’s bolt. But Taccom does seem to have produced a genuinely good bolt with a lot of features, and it’s not horribly expensive for what you get.

As noted above, the pinned weight in the bolt had to come out. Removing it took a surprising amount of pounding on the roll pin. It came out eventually. I had no other issues with the bolt installation. You do have to be careful when handling your upper, since the bolt likes to fall out (there’s no gas key to be retained by the charging handle). I would recommend that maybe Taccom offer a version of the ESSB without the weight installed specifically for use with the DBRS.

The ESSB comes with the short stroke extensions you put in the back of the bolt, but I was informed that those are not necessary with the DBRS (which naturally short strokes by total limiting bolt travel), so I left them out. Short-stroke operation is the current hotness with competition PCC shooters, since it reduces recoil slightly by limiting bolt travel. (Your bolt/BCG does not need to travel as far since the 9mm round is so much shorter than a 5.56 round!) This has all sorts of fun knock-on effects that the ESSB is designed to mitigate.

With my rifle upgraded, I took it out to the range for a test fire!

The recoil was MUCH different from the usual straight blowback AR-9 recoil. Straight blowback gives you a very heavy, “slow” recoil. The DBRS transforms that into a much faster, more AR-15-like recoil impulse, but one that moves the gun less than straight blowback. This feels counter-intuitive, until you realize that by subtracting all that weight out of the bolt, you will naturally have it move faster even after overcoming the initial magnetic resistance.

Unfortunately, not all was well, and I experienced a few instances of burst fire followed by a “high” misfeed. This was presumably due to a real short-stroke, causing the hammer to not be reset and the magazine not getting the round up in time. (I know the usual assumption is a bump-fire, but I feel confident that was not the case here.) Burst fire is great when you’re expecting it to happen, but not so great when you’re not expecting it. Notably, the gun was very controllable during burst fire, so that also further sold me on the recoil system.

I got in contact with Taccom, and was able to talk to the owner. We chatted for a bit, and suggested I change out the green springs on my Hiperfire trigger to the red springs. This seems counter-intuitive, but it turns out that the “lighter” springs actually increase the hammer power on the trigger, which means more resistance to the bolt resetting the trigger. This isn’t a fun process (those springs are the toughest part of the trigger install), but I managed it.

While my gun not functioning correctly wasn’t a great experience, I was very impressed with the customer service I got. Not a lot of companies have the owner calling you to help troubleshoot your gun, especially with interactions with components that are not made by them. The AR-9 platform is really the wild west of AR derivatives, with not a lot of standardization.

After doing all this, I took my PCC out for another test fire at an action shooting training session, with the hopes that the problem would not repeat. Unfortunately, the problem was still there; I was having a lot of doubles and associated misfeeds with my 147gr reloads, which work just fine in every other gun I’ve used them in. Basically, if it won’t run those, I don’t care if it’ll run anything else, it’s not going to work for me.

I also noticed what seemed to be some sort of break-in with the DBRS. It seemed smoother and easier to pull by the end of the range session. Not “lighter” necessarily, just not as much of a chore, like it had worn in. The DBRS has a lot of moving parts (including two springs), so it’s not necessarily surprising that some parts might have been rubbing together initially.

However, I was able to focus more on what was going on with the sights, I was very impressed by the difference. The sight rise was very consistent, and very minimal, even blasting it at 25yds (3″ up and right on the target, like clockwork). This is counter-intuitive from the first impression I got, which was that the recoil had increased. It feels sharper, but the overall movement effect is genuinely less than with those heavy bolt/buffer weights bouncing around.

I took one more stab at it, and swapped out the Hiperfire for an ALG Defense ACT trigger that I had laying around from another upgrade. If that wouldn’t work, I’m not really sure what would. The ACT isn’t my favorite trigger in the world, but it’s smooth and has an acceptable midweight trigger press… in the end, it’s a rifle, I just need something in the 4.5lb range so I’m not moving the gun around. when pulling the trigger. Super fast splits aren’t a Steel Challenge thing.

In the end, I gave up. Taccom was very nice about this, and traded me their 3 stage buffer to see if that would work better. The 3 stage buffer is an interesting setup – it consists of a normal buffer spring, a hollow buffer with a secondary buffer in it (not too dissimilar in concept to a hydraulic buffer), pre-load rings, and a short stroke plug at the back of the buffer tube. This buffer system assumes a full-weight bolt, so I reinstalled the weight into my ESSB. You also use a buffer detent to retain it, so I reinstalled that and since I had my lower in a block, put the Hiperfire trigger back in, too. I’m getting pretty good at this… too much practice.

Picture stolen from Taccom. The layout shows you how the 2 stage buffer all fits together. Wish the inner stage was captured in the outer buffer shell, but the manufacturing efficiency is hard to deny

Thankfully, this new setup worked considerably better. The 3-stage buffer has a secondary buffer that not only lessens initial impact jolt, but also cushions the return blow of the buffer against the bolt. A little more dot rise than the DBRS gave me, but also much more reliable and still tamped back the recoil substantially over a normal 9mm buffer setup. It was unclear to me whether I needed the pre-load ring or not, but leaving it in didn’t seem to affect anything. Short stroke was noticeable; the ESSB left my BHO intact, but my LRBHO didn’t seem to want to work in most of the mags I tested. I think an extra power spring might have restored it to functionality.

While I did have the sense that I was beta-testing the DBRS, I was impressed with Taccom’s customer service. I had a problem, and the owner of the company made sure I got my PCC running again. I also realize that 9mm AR-15s are just not standardized enough to assure compatibility, and ammo choice can make a huge difference in reliability. I was also not necessarily thrilled that I had functionally spent $160 and a bunch of my time/ammo on what ended up being a $95 buffer, however.

The test for this new, hopefully-reliable setup was the AGC outlaw steel challenge match in September. I had some brief problems with ammo and an extended magazine at the beginning of the match… and then this happened a few stages in:

I know this isn’t blazing fast shooting by a lot of standards, but it was enough to net me my first overall stage win at a match. The new trigger and the enhanced buffer system made a substantial difference in my ability to transition and shoot accurately at speed. I wound up coming in 7/78 with my PCC, and easily saw how a more reliable mag and ammo could genuinely have put me in a position to come in on the winner’s podium.

Thus concludes the new round of upgrades… new trigger, new buffer system, and new bolt. I think I’m pretty close to done at this point. The barrel may need a bump to 16″ to comply with SASP PCC rules, but I suspect I’ve taken this gun as far as it’s going to go otherwise; if I decide to bump up my PCC game any further, it’ll be with a Sig MPX or CMMG MkG. From a price-performance standpoint, though, I’m happy where I am for now.

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