Sometime around the beginning of 2020, Hiperfire contacted me about reviewing their new PDI drop in single stage trigger. Since I really like the other triggers I have from them, I suspected this one would be nice also. When it finally arrived in September, I was not disappointed.

The Hiperfire PDI is their latest “drop in trigger” system for AR15 style rifles. They even make one specifically for the Sig MCX platform also. Usually when I think of a “drop in trigger”, I think of the cartridge style, where all the parts are contained inside a cartridge, that just drops in where the trigger assembly goes. The PDI is slightly different. It is essentially a cartridge style, but with the hammer spring feet extending forward, like a standard GI trigger assembly. Installation is pretty straight forward for anyone used to dealing with AR triggers. It also comes supplied with an anti-walk pin set.

If you have ever seen a Hiperfire trigger, you know that they look a little different than a normal trigger. The PDI is no different. It uses a curved trigger with a “backbone”. The backbone consists of a toothed section on the back of the trigger shoe. One of the purposes of the backbone, is to install their “Hipershoe”. The Hipershoe is an adjustable finger pad that can be moved up or down, depending on user preference. Using the Hipershoe will also allow slight adjustments in trigger pull weight. If you move it down, it slightly lowers the trigger pull weight. Moving it up slightly increases the pull weight. The drawback to this is, may it be ever so slight, that more creep is added to the pull, when the pad is in the lower positions, and more trigger pull weight is added when in the upper positions. I only really noticed this when shooting slowly, as in precise aimed shots. The Hipershoe also helps individualize the trigger, by placing the shooter's finger in a better location for him or her.

One of my favorite aspects of the PDI trigger is it’s hammer energy. Lots of aftermarket triggers reduce the hammer strike energy to lower the trigger pull weight. Not the PDI trigger. It has Mil-strength hammer strike energy. What does that mean for you? Well, it means that you will probably never have a misfire because the hammer didn’t hit the primer hard enough. My sample PDI worked with every type of ammunition used, from steel cased .223 to 9mm and even .22LR.

My Second favorite aspect is the trigger pull weight. It comes in at a 2 lb fixed pull weight. Yes, 2 lbs. When I first installed the PDI, it measured 2-¼ lbs, but with some use, came down to the stated 2 lb weight. As mentioned earlier, the weight can be finely adjusted by moving the Hipershoe up or down the trigger face. When I say slightly, I get about ¼ lb difference in pull weight, from the top setting to the bottom setting. My least favorite aspect of the PDI, also includes trigger pull. There is quite a bit of initial creep in the trigger before it releases. When shooting fast, it is not really noticeable. But, when shooting slow, precise aimed shots, it is annoying. As the Hipershoe gets moved farther down, for the lightest pull available, this creep gets more noticeable. The trigger reset has to be mentioned. It is very positive, that trigger snaps back way better than I expected, basically like a standard mil-spec trigger.

The PDI trigger can also be used in Pistol Caliber Carbines (PCC’s). The design has a hammer collision bumper and disconnector crash protection. This allows the hammer to reset properly under the harsh direct blowback of most PCC’s. PCC’s tend to bounce hammers from their harsh recoil impulse, especially with lower trigger weights. Thankfully, Hiperfire has alleviated this with their PDI trigger. I ran the PDI in a 9mm PCC. I had zero times where the rifle went more than one round per trigger pull, something I can’t say about other PCC triggers I’ve used.

I used the PDI in just about every type of situation I could think of. It ran flawlessly in all of them and was a joy to use. Since I don’t use this trigger for slow fire, the creep was not an issue. The trigger pull weight is just awesome. I am able to shoot super fast double and triple taps, thanks to the PDI. This applies to 9mm, .223, and .22LR. I even use it with the “Blackbeard” system from MantisX. I really do think this trigger improved my speed on follow up shots. I even dropped the rifle with the PDI in it, and it still works as if it were brand new.

The Hiperfire PDI drop in trigger is everything they say it is. I just can’t get over the 2 lb pull weight in a drop in trigger system. Yes, it might be $180, but it’s not the highest priced drop in out there. If you are looking for a good AR15 trigger, for PCC or anything else, definitely go check out Hiperfire and the PDI.

Firearms Insider Reviews - 8 Key Points

Claim to Fame:

Smooth, light, drop in trigger for AR15”s

Target Market:

Those wanting a nice drop in trigger that will work in just about any AR configuration

FNBs (Features & Benefits of this product):

MIL-Grade Hammer Strike
H&M BLACKNITRIDE Finish
Hammer Collision Bumper
Disconnector Crash Protection
Disconnector Spring Crush Protection
Curved Trigger Bow with a Backbone
HIPERSHOE
Drop in assembly
2 lb trigger pull weight

What other aesthetic options or finishes are available?

SIG MCX, Titanium-Nitride or Titanium-Carbon-Nitride coatings

What others are saying?:

5/5 stars on Brownells

WELL DESIGNED

I installed the trigger in a Quarter Circle 10 PCC and would comment the second trigger pin was a little tight to get through the hole. Not saying this is a problem just an observation. The trigger breaks between 2.5 and 3 pounds and has a nice feel. The reset is short and is very audible. No failures or problems after 500 rounds (practice and 2 gun match). I feel the trigger is a good value, appears to be well made, and should hold up to the demands a blow-back bolt places on a trigger.