22LR AR-15 conversion legal w/evil features?

[B yond]

I'm looking into building a CA-legal AR. I'm wondering If I can build it for 5.56 and use one of the conversion kits to convert it to 22LR, then put a pistol grip on it legally.

Will that pass muster or does it need to be a dedicated 22LR upper?

[Arteel]

When you have the conversion kit in the upper, you can have all the evil features with no bullet button.

When you switch back to centerfire, make sure you put the bullet button back on FIRST. Otherwise, you will create an AW if you still have evil featurs on the rifle.

[resident-shooter]

Rimfire weapons are not restricted from not having bullet button.

[B yond]

Thanks guys, you're awesome!

Now my next question... 1:7 or 1:9 twist for a 5.56 barrel with a 22LR conversion? I've heard that the 1:7 twist patterns more than it groups, so is the 1:9 significantly better?

[Seesm]

No BB needed on the rifle when the .22 kit is installed... Makes most sense to have all your rifles configured this way for ease of use.

[NeoWeird]

Thanks guys, you're awesome!

Now my next question... 1:7 or 1:9 twist for a 5.56 barrel with a 22LR conversion? I've heard that the 1:7 twist patterns more than it groups, so is the 1:9 significantly better?

Standard .22 LR ammo uses a 1:16 twist rate for proper bullet trajectory. You can use a faster twist rate, but it can be detrimental to accuracy or even damage the weapon (not really an issue in this case). If this is going to be SOLELY a rimfire gun, I'd go for a dedicated barrel. If it's going to be a plinker that you use factory ammo that you switch back and forth between, I'd lean towards a 1:9 barrel. If you're going to use the 5.56 barrel for heavy bullets, I'd suggest going the two barrel route as well.

[Variable2147]

Standard .22 LR ammo uses a 1:16 twist rate for proper bullet trajectory. You can use a faster twist rate, but it can be detrimental to accuracy or even damage the weapon (not really an issue in this case). If this is going to be SOLELY a rimfire gun, I'd go for a dedicated barrel. If it's going to be a plinker that you use factory ammo that you switch back and forth between, I'd lean towards a 1:9 barrel. If you're going to use the 5.56 barrel for heavy bullets, I'd suggest going the two barrel route as well.

what are your manufacture/model recommendations for "Dedicated barrels"?

[Josh3239]

Spikes's has a couple uppers and barrels stripped in .22LR. They are made by Green Mountain.

[Variable2147]

Spikes's has a couple uppers and barrels stripped in .22LR. They are made by Green Mountain.

dang you! you got my hopes up...those barrels say specifically "will not work with 22lr conversion kit." you have to have the dedicated bolt.

[Josh3239]

I was under the impression it was for a dedicated .22LR, meaning the upper would only shoot .22LR. If so you would want the .22LR bolt and barrel. If your going for a conversion to my knowledge you would need the 5.56mm barrel and a conversion bolt.

[NeoWeird]

The difference between the dedicated bolt and the drop in unit is the collar at the end of the unit. On the drop in unit it is the chamber adapter that fits in the chamber, on the dedicated unit the portion that looks like the cartridge is milled off and the result is a collar that slides over the .22 barrel to locate the bolt properly. Other than that, all parts are the same. You could PROBABLY even contact the manufacturer of your drop in unit to buy the collar or you could just modify your unit. I personally don't like destroying parts if I don't have to and I would either buy one direct from the manufacturer or have one custom built by someone.

As for barrels, there are three major options.

1. Use the drop in unit with regular ammo. The lighter bullets will be adversely effected by the faster twist rate, but they should function more than adequately for general plinking.

2. Dedicated barrel. In this regard, I think any of the companies that make conversions will be fine - even M1S should be fine. Keep in mind that .22 LRs are... picky to begin with. All dedicated barrels will probably require slight modification or a good wear in period at the very least. I am NOT an advocate of barrel break in with regards to cleaning. Just shoot the hell out of it and it should be fine. Spikes, CMMG, Model1Sales, etc should all be fine. If you NEED one for supreme accuracy, such as a target rifle, I'd opt and spend the extra $100-200 to have a quality barrel, like a Shilen or Lilja, made and custom fitted to your rifle. Other than that, regular dedicated barrels will be fine.

3. The last major option is a compromise between the two. Use the drop in unit with Aguila's Subsonic Super Sniper ammo (frequently abbreviated SSS). The Aguila SSS fires a 60 gr bullet using an elongated bullet in a .22 short case as opposed to a ~38 gr bullet from a .22 LR case. The result is the same overall length and function as regular .22 LR ammo but with a heavier bullet. The bullet is best stabilized in a 1:9 twist barrel which is what most AR manufacturers make. The bullet should be stabilized relatively well, is a heavy bullet which makes it good for hunting, and it fires at subsonic speeds which is both optimum for target shooting and those lucky enough to run suppressors. It's also Aguila so it's relatively cheap but dirty.

Personally, I find dedicated barrels more more appealing which is why I switched from a drop in unit to a dedicated upper. Other than personal prefence, for general plinking, I'd say just shoot it and go to town. If you got the money, go for the dedicated unit, if not the drop in unit is fine. If you are just plinking, shoot whatever. If you want to shoot varmints or have something a bit more stable, use Agula SSS ammo.

[5150bronco]

so heavier bullet in 1:9 barrel than, right? thanks.

[B yond]

Well guys, thanks for all your advice and help. After much reading on this site and much research into the legal mess that is CA's gun laws I've purchased my parts am almost done building my rifle.

Stag OLL - 175
Blackthorne dedicated 22LR (1:16) flat top M4-style upper w/ quad-rail gas block - 350
DPMS parts kit - 50ish
6-position collapsible stock - 60ish

Also slapping on a bipod and cheapo scope I had laying around...

Once I get it finished I'll post pics.

All-in-all it's costing about what the colt 22LR M4gery would've cost from Big 5, but I'll be able to swap the upper and evil features to make a centerfire rifle down the road if I choose to, so I think I'm better off.

[B yond]

m4gery-1.jpg

m4gery-2.jpg

[Droppin Deuces]

Beautiful looking gun. I'm about to start putting something similar together myself.

If you don't mind my asking, what made you decide to go with the Blackthorne upper?