I have a Colt SP-1 conversion waiting on a stamp.  Which nowadays could be anywhere from 1 day to ?? who knows.

I've looked into 22 uppers on the various websites and this is my shopping list so far:

Upper receiver and bolt group   from right to bear??

Barrel - probably go with 10" to 12"   not sure where to get that, borebuddy site has them

Magazines - S&W 15-22

Magazine well adapter

Adjustable trip kit from borebuddy

Adjustable bolt weight from borebuddy

Pressure plug from borebuddy

Front lower to upper takedown pin size conversion.


I don't really like the space gun skeletonized foregrip look, I would prefer if it looked like a Colt Commando.  So I guess I need CAR15 handguards and the hardware to mount them.

Any advice that you could offer on what to get exactly, and from whom, or any tips or tricks would be very appreciated.  I'm starting out at ground zero.

I looked the internet over and there are lots of threads about this, but most of them are pretty old.

Thanks

This is the look I'm going for:

Go the "AR15 forum", then the "Rimfire and Pistol Caliber" subforum.
At the top you will see "Important Rimfire Threads", click on it.
Then click on the "How to make your AR22 run smother" thread.

https://www.ar15.com/forums/ar-15/How_to_make_your_AR_22_run_smoother_NOW_with_pictures/15-526872/

You will see lots of tips and techniques on how to tune a 22 upper to run full auto.
Remember that a M16 was not designed to run full auto in .22lr so you will likely have to do some or all of the mods to make it do so reliably.
Most of the mods are done to reduce friction, which is the enemy in a .22lr blowback system.
Personally, I have found that if I load more than 22-23 rounds in a magazine I can have trouble as the rate of fire can be such that it can outrun the single stack/single position feed magazines ability to present rounds.
i also have the best luck with Black Dog Gen 3 magazines, the ones with the loading button and metal feed lips.
Once you get it running well, it is a joy to shoot.

RCA

I pieced together a bunch of different shit on an SP1 upper to get away from the adapter pin.  I used a CMMG conversion &  sear trip/ABW, RTB 16” barrel and misc. parts from Bore Buddy to get it running properly.

The SP1 upper will need the relief cut for the sear if you go that route.  The S&W mid length handguards are the way to go if you can’t get a barrel that uses carbine length pieces.  I think the FSB was from RTB, but is F marked and advertised otherwise, still works fine.  The recoil spring assortment, replacement extractor and firing pin, both with springs, are what I used to tune it all to run.

BDM mags with plastic feed lips seem to work the best with mine.  The metal ones, not so much.  Haven’t worn out the plastic ones that I’ve owned for 20 years yet.  Not concerned about it either.  HTH!

CMMG.

3k rounds, almost all F/A dumps. Zero hiccups.

I run the CMMG M4 .22lr upper with the trip, weight, and most of the mods in the thread I referenced in my earlier post.
Runs as close to 100% as is possible in this platform.

RCA

I've got an older Ciener kit with the chamber adapter which I use in a couple different 5.56 caliber uppers on a SP1 RR. The bolt & carrier have the ball / detent mod. Both uppers have the gas tube removed or the gas port in the front sight base plugged. Both are Colt large hole uppers that have the sear relief machined into them.

I do not run the ABW or any type of spacer between the buffer and carrier. I stuck a couple O rings inside the barrel extension which helps to hold the chamber adapter in place. I polished the feed ramp on the chamber adapter, the guide rails and the guide rod. Recoil spring free length of a new Ciener spring is 9 3/8” I cut a Lakeside spring to 9 1/4” and installed it. If you cut a recoil spring remember to anneal the cut end so it closes up.

This setup has a high cyclic rate and functions near 100% when clean & lubricated with HV ammo. After 300 rds or more the bolt face & adapter benefit from a wipe down and more lube on the rails. Doesn't seem to care about mags - runs well with the metal Ciener or CMMG style plastic mags. FYI - Arms Unlimited has their 25 rd CMMG style mags for $9.99 right now. I prefer the CMMG style mags since they hold the bolt open when empty and being plastic don't scratch the magwell like the steel mags but you give up 5 rds.

I also have a CMMG style barrel collar and a compatible barrel with the proper 1:16 twist rate, these are RTB parts. My plan was to replace the chamber adapter with the collar on the conversion carrier (with ball detent mod) and run this upper on my DIAS lower but it hasn't worked out too well. I clearly have a timing issue but decided not to waste time fussing with it since the chamber adapter version runs great on the SP1 lower. That said the accuracy of the RTB barrel is outstanding so I play around with it on a semi SBR lower.

Sure the 5.56 barrels aren't as accurate as the RTB but nobody has ever complained after shooting it, you can still hit steel or tear up cans with ease. Remember the machinegunner moto: accuracy through volume!

I have a CMMG setup that I put together using their barrel and bolt group. It runs great but can be picky with fcg (Geissele SSF runs great, LMT 2-stage FA does not) and you need to find what ammo yours likes then stick with that.

https://cmmg.com/barrel-and-bolt-group-kit-9-mc-22lr

You’ll need the anti bounce weight and autosear trip too.

I use Black Dog mags.

What barrel lengths are you guys using?

Thanks for the info provided so far, BTW

One of my 5.56 barrels is 20", the other is an old barrel that is cut down to somewhere between 9" and 10".

The RTB CMMG style barrel is 9".

9”

I'm running a CMMG 16" M4 style with front sight base, flat top with carry handle sight.
Went with 16" as I can run it on other non-nfa lowers.

RCA

16” here.

What rimfire ammo is preferred and what is to be avoided?

I haven’t yet tried my CCMG 4.5” upper on my M-16.  I usually shoot that upper semi with a suppressor and CCI SV but it seems like I’ve had trouble with bulk pack (Federal maybe) feeding.  Have plastic CMMG mags.

I have the best luck with 40gr. CCI AR Tactical and 40gr. CCI mini-mag.
But I'm not shooting suppressed or short barrel.

RCA

Get a bunch of different brands and see what it likes.

Over the years Aguila copper plated 40 grain RN has been a favorite. Prior to that I shot a bunch of Winchester Super X.

I swore off all things from the Remington rimfire catalog 20 years ago but their current production Thunderbolt ammo has worked very well.

The past couple years Fiocchi has been in stock at a LGS and their Field Dynamics HV stuff runs okay for me.