22 ARC Kits and 22lr Dedicated Upper Builds

[GarandTd]

I have been obtaining the parts to build a dedicated 22lr upper. I've run into a bit of a roadblock in that I cant find a barrel. I currently have a stripped upper receiver, RTB bolt assembly including the barrel collar, and 2 25 round mags. Since I can't find the barrel, I ordered a CMMG chamber insert to use in the meantime. I still want to build the dedicated upper, but I don't know when a barrel will be available again and I want to be able to use the bolt with 22lr in the meantime.

Tell me about your experiences with 22 ARC Kits and or building a dedicated 22lr upper.

[zukiphile]

Tell me about your experiences with 22 ARC Kits and or building a dedicated 22lr upper.

I spent a decent bit of time and money horsing around with 10/22s before I realized that I was looking to fix accuracy problems that the 10/22 isn't well positioned to overcome. I had assembled ARs, and took the next foreseeable step.

I had read about poor reliability in 22lr ARs and braced myself for problems that never came. My very first attempt functioned with every time of ammunition I had. The free floated barrel was cheaper than most 10/22 barrels and didn't need pressure pads or specialty v-blocks to print good groups. The Geissele I used was half the price of my old Kidd trigger.

Problems I hadn't foreseen include firing pins breaking and my favorite magazines, ten rounders made by S&W for their 15-22, having a life span of only several thousand rounds as a result of feedlip wear.

The bolt doesn't weigh as much as it should; it's a couple of ounces lighter than a 10/22 bolt. Bore Buddy makes bolt weights and improved firing pins to address those problems.

People make a big deal about a specific kind of malfunction in which extracted brass gets caught in the hollow of the charge handle. In 25,000+ I've never had that happen, though I did once have an emptied case find its way into the receiver port for the gas tube.


Barrels at a price I wanted to pay were hard to find even back when the market was swimming in lots of parts and ammunition.

[GarandTd]

I understand the accuracy limitations of the conversion combined with an insert in a 5.56 barrel. That's why I still ultimately would like the dedicated upper with proper bore and twist rate for 22lr. I also could have saved a lot of time, money, and hassle by just buying a 10/22, but I'm more interested in the build.

I've seen some of the bore buddy accessories available for use with these bolts. Do you have the piece that compresses the buffer spring and puts forward pressure on the bolt group? I think that may be intended for the chamber insert set-up as opposed to the dedicated upper.

[zukiphile]

You aren't likely to save money just buying a 10/22, because it's unlikely that's all you'll buy.

I've seen some of the bore buddy accessories available for use with these bolts. Do you have the piece that compresses the buffer spring and puts forward pressure on the bolt group? I think that may be intended for the chamber insert set-up as opposed to the dedicated upper.

I do not have that piece, and I agree that it may serve a purpose where a chamber insert and centerfire barrel are present. I have an insert, but I've never used the insert.

I purchased a prototype brass bolt weight. The center strut broke pretty quickly. He sent a stainless weight; that same strut part broke after a few hundred rounds, but it still works well. He offered to sent a replacement, but I declined since the stainless one still works.

I'm a fan of his bore guide for cleaning, and his polymer buffers last longer than the rubber grommets some people use to dampen the metallic clack of the action. I have his extractor springs, and one of these days I'll place another order that will include his improved firing pin.

He's an engineer of some sort, and his pieces feature improvements worth having.

[GarandTd]

I ordered the basic reliability kit from BoreBuddy. It includes the buffer tube plug, bolt buffer, charging handle insert and increased power extractor springs. I also ordered extra bolt buffers and the delrin forward assist plug.

zuki, tell me about the broken firing pins. How many times did you experience that? How many rounds when it happened?

[MarkCO]

I used to actually sell complete AR dedicated uppers. They were high end and while mine, and most of them ran perfect, it was 1. A small market and 2. Folks wanted to run cheap ammo in them.

I used Velocity bolt carrier groups, Nordic CH and upper receivers, my own handguards and barrels were from Beyer, which I found to be the best in terms of chamber, accuracy and reliability. http://beyerbarrels.com/barrels/ar15_barrels With match grade ammo, under 1 inch at 100 yards was routine. I did a few things to tune the complete uppers, but with Black Dog magazines in a standard AR15 lower, they were very good.

[GarandTd]

I've checked out the beyer site. I was hoping to be able to find a barrel for under $200, but I don't think I'm going to have much luck there. I will be putting strong consideration into Beyer. I've seen them recommended multiple times and I have no reason to doubt the value.

[zukiphile]

zuki, tell me about the broken firing pins. How many times did you experience that? How many rounds when it happened?

I broke three pins. Rounds counts were 4,000, 400 and 3000. A contributing factor imo was my use of a Larue two stage trigger, which has a very heavy hammer spring. I was also using five Taccom shims to limit the depth of the pin strike. CMMG has sent me a couple of new pins whenever I needed them and without charge.

I've had no breaks since switching to reduced power hammer springs and taking off all the FP shims.

At the same time I rounded the head of my firing pins so the hammer can only strike the center of the pin. Since making those two changes, I've put 13,000 rounds on a pin.

The Bore Buddy pin has a rounded head and the steps in the pin are radiused to decrease the probability of snapping.

[GarandTd]

A barrel became available at a price I was a little more comfortable with. It's a 16" 1:16 twist light weight pencil profile with a nitride finish. I ordered it this morning. I am going to return the chamber insert since I do not need both.

[9x19]

Check your collar and barrel stub length, before you assemble the upper.

CMMG made a quiet change some time back from .672" to .700" (recently discovered by some folks while building .17HM2 uppers with custom barrels from Lothar Walther)

If you have the long collar and short stub, you can correct the collar length with a flat surface and some sand-paper... or contact CMMG and they may be able to swap.

Good luck

[GarandTd]

Thanks, 9x19. The bolt assembly, collar, and barrel are all from RightToBear. I believe CMMG is the maker of RTB branded products. All of these parts were acquired this year. I'm hoping continuity of manufacturer will help this build be a success. I'm planning to return it, but the chamber adapter is also CMMG.