ZRO DELTA CRITICAL CAPABILITIES LLC AR-15 LOWER PARTS KIT

this kit installed easy and a decent trigger for the price I wouldn't hesitate to buy again

I purchased 2 of these kits. One of the triggers gets hung up, and actually fired when I set the gun down. The trigger kept getting stuck and would not fire. I havnt checked what is going on with it yet. The other kit works fine, but is rough. Just spend a little more. It's worth it



Remember:

No trigger gaurd pin

No grip screw

I've used 6 or 7 of these kits for builds, one had the wrong takedown pin detent spring, no biggie, I had a spare, the thing is, every kit had an outstanding quality gi trigger group right out of the package. Far better than any other kit I've used, and I've built dozens. These guys got it right and a great price too, best lpk deal out there as far as I'm concerned.

I've used a few of these kits, they give a nice trigger pull as is. It doesn't take much polishing to make a super smooth and crisp pull. All the rest of the parts fit and function as they should. I use this kit for every build, the price is reasonable and quality is excellent, enough said.

This was my first AR build and I was working on a budget, so I decided to buy this on sale. What attracted me was the direction of grind on the trigger and hammer surfaces, and I'm quite pleased with this. Everything fit perfectly in my Anderson lower. I was surprised by how exact everything fit. It has a nice smooth pull that got even better after about 30 rounds and a really short reset. I also used an Anderson upper with a 16" barrel and a buffer tube/spring/weight from Brownells that was a Brownells brand and that worked perfectly too! The carbine has worked perfectly from the first shot. I couldn't be more pleased! I wouldn't hesitate to buy another one of these kits! At these prices the entire built was under $400.!

Poor quality finish. some parts had the be filed, sanded and hand fitted to work. Casting marks on most parts were still there. Seems like some of the parts have been painted black instead of the normal mil style finish. Like others have said the buffer retainer would not fit and needed the black paint sanded off of it before it would fit down into the receiver. The trigger and hammer pins needed to be ground down near the grooves because they had ridges of metal that had been pushed up on each side of the grooves that made them oversized in that area. The front of the hammer had casting marks in the front curve that would rub on the inside of the receiver causing it to hang, needed grinding to work. Mag release had burrs causing it to grind in its slot. Quite a bit of hand fitting needed. Trigger actually feels pretty good once I got everything fitted. Black paint style finish is weird though. I would recommend getting a slightly better quality LPK instead.

Most of the parts in this kit seems serviceable standard drop-in type parts. The hammer however, was incompletely cast. The hammer notch on the hammer looks like it was never fully cast. I have not tried yet , I may be able to save it with some careful Machining. There's a large blob of material that almost looks like surplus weld right on the end of the notch. It also dips significantly from side to side making the notch very shallow on one side and very deep on the other. The goal is to machine away the high side and the blob of stuff and hopefully end up with enough material left to provide engagement so that will be a functioning hammer.

This is the 3rd AR I have built and I loved the concept and the price point of this kit. However the quality did not live up to my expectations.

Pros-The small parts looked to be of good quality. Nice finish and nice machining work of MOST of the parts. Springs were correct length and spring rate.

Cons- QC on this kit leaves much to be desired. First issue was there was a large burr on each side of the channel that was machined into the front take down pin. I was able to make this fit with a file and diamond hone.

Then I tried installing the FCG and to my dismay I found one of the trigger pins had the large burrs around the channels for the hammer spring to lock into. I didn't even try to work this one in and I used a spare I had in the parts bin.

The trigger to me is nothing to brag about. The stock trigger in my M&P 15 Sport feels way better. I didn't measure the original pin compared to the spare I used so that may be throwing it off but I will most likely be replacing this with an ACT or PNT trigger in the future.

Giving it 3 stars because at the end of the day I have a working lower.



That said I have never experienced headache like this kit. The parts are such tight tolerance I almost thought they were off spec. If you can afford something else get that, if you really can't then this kit is passable, if a bit frustrating.

Ordered this parts kit to install in an Aero Precision lower receiver. All parts worked and fit perfectly with one exception. The bolt catch plunger was too big to fit inside of the receiver. Even minor filing could not reduce the size so it could fit. Found another plunger at a gun show and it fit perfectly.



The trigger seems crisper with less overall travel than my other AR. The takedown and pivot pins seem to be of higher quality than my other build as well.

Good smooth feeling trigger, clean brake. I didnt have any issues with the function of this kit. It was installed in an anderson lower and the fit of all the pieces was great, but it was missing my mag release button. No problem though as Brownells customer service is the best! I let them know of the issue and they sent me one right away.

Not only do the polished trigger pieces make for a great crisp break, the front and rear takedown pins are a good snug fit in my Spike's Tactical lower.



You can't beat this kit for the price it's at.

Ordered three of these, one kit did not have a safety selector detent. Haven't installed yet, but appears to be of good quality in my limited experience (will be my 5th through 8th build). Called Brownells and they are shipping the missing part within 2-3 days. Customer service has been excellent. One star off just for quality control in kit assembly (which isn't unique to this kit or this supplier). Will continue to order from them!

Upon opening up this kit and putting it into my lower I was excited and hopeful for good things. As the build moved into completion and a trip to the range I found trouble. The disconnector does not release the hammer back to the ready position causing the trigger to only "reset" if you push the trigger forward. I'm going to try some light polishing to see if that helps. I may also try a different discconector spring as this one seems to be too stiff.

Very nice parts kits at a great price! I purchased 4 of these and all were complete and had no issues. The fire control groups were better than most that I see in LPKs. Just ordered a few more!

Smooooth trigger pull as is, but a little polish with some 600 grit sand paper makes the take up travel glass smooth. The rest of the kit is perfectly serviceable.

Great deal on great parts. I've used these parts in over a dozen builds and have never had a problem with them. Look and work great in billet, or forged, receivers.



I think the original post was more about driving his own business than actual experience with the parts.



Recommend these parts for any builder looking to put together a quality rifle.

The trigger is smooth on this kit. Pic attached--the grind is definitely different. It's nothing crazy amazing, but it is does provide a nice pull. The hammer engagement area has a nice finish, too.



The small parts (pins and detents) were very well done. Sometimes they can be rough depending on the material and finish. For the money I'm happy and have always been happy with Brownell's products.



<img width="500" src='/userdocs/reviewimages/bfc1caa5-1b89-4bd0-bba2-301a95af8a5c.jpg' alt=''>

I've used these kits to build billet and forged receivers, and have had great results on each. No problems with fit, finish, function, or reliability.



Maybe the bad review is because he's trying to sell his own import parts...I can guarantee I've never had a problem.



Strongly recommend!

I've used this build kit repeatedly and have never had a problem installing them or with the function of the parts.



Great option to save money buy not paying for parts you don't need for a particular build!



If you know what you're doing, this is a great option.

Purchased three LPK's. The finish on all three kits was different. The grind on the triggers was rough. The threads on one mag release was no good. The disconnector springs were poor. I buy a lot of LPK's from Brownells in the hundreds a year range.