AR conversion kit vs dedicated .22 upper

[Glocker619]

Quick question about .22 AR's. Why buy a dedicated upper when there are conversion kits out there that can convert a 5.56 rifle to .22LR? I like the option of being able to shoot both types of ammo. What are the pros and cons of each option?

I wanted to build a lightweight AR for the wife and she shoots a lot of .22, but would like to be able to have her shoot .223 once she gets confortable with it.

[rjf]

The dedicated upper barrel has the correct slower twist rate for accuracy with the .22 LR.

[Glocker619]

The dedicated upper barrel has the correct slower twist rate for accuracy with the .22 LR.

Is that the only advantage? what is the correct twist rate and does it really effect accuracy that much?

[ejhc11]

The dedicated upper barrel has the correct slower twist rate for accuracy with the .22 LR.

+1

If you can afford it get a dedicated rimfire upper, you can get by with the conversion kit but remember your sights and optics were sighted in for the centerfire also. Yes, accuracy will be great almost twice of what a dedicated rimfire upper can do and it won't be consistent groups.

[NorCalDustin]

Is that the only advantage? what is the correct twist rate and does it really effect accuracy that much?

Yeah... It does have a big impact on accuracy... But the question is, how accurate is accurate enough for you?

[shadow65]

Depends on your barrel.
In general, as stated, a dedicated upper will cut your groups by half over a conversion.
Conversion in a 1/9 barrel will give you about 2-2.5" at 50 yards.
A dedicated upper will give you 1-1.5 at 50 yards

Some worry about the effects of shooting .22 through a gas system. I've never had an issue. But the common sense rule applies. Don't shoot 3000 rounds of .22 through a 5.56 gas operated system without cleaning it and expecting everything to be fine.
I pull a bore snake through my barrel after 300-500 rounds of .22, then shoot 3-5 rounds of 5.56 to blow out the gas system. Clean as usual when I get home.
Dave N