.22 LR adapter for a 5.45 Upper

[zeus45c]

Does anyone know if a Spike's or CMMG rim fire adapter can be modded to work in a 5.45 x 39 AR Upper? I am looking to build the ultimate cheap ammo upper and this would fit the bill. I already found one that is based on the M261 GI unit but I would prefer something patterned after the more popular ciener kit.

[Quiet]

Don't do it.
.22LR bullets have a bigger diameter than 5.45x39mm bullets.

[CSACANNONEER]

"The ultimate cheap ammo upper" would be a dedicated .22lr upper.

[zeus45c]

There was a discussion about this on another forum and they quoted the 5.45 barrel as being an even better fit for a .22 than a 5.56. IIRC, they said the size was actually .221.

I just did the conversion and 5.45 mm is .214 inches. Quiet, do you know if the size is dead on or the Soviets decided to round down the nomenclature for some arbitrary communist reason.

CSA, I like the idea of being able to shoot both out of the same upper. Plus, even with the cost of the RFA assembly and the 5.45 setup I am looking at, the $$$$$ would be the same as a dedicated upper.

[Variable2147]

from wikipedia: 5.45 - Bullet diameter 5.60 mm (0.220 in)

5.56 nato - Bullet diameter 5.70 mm (0.224 in)

.22 long rifle - Bullet diameter .223 in (5.7 mm)

i don't trust this data if i can look at a reloading manual, but it looks like a no-no like "Quiet" said.

[zeus45c]

Thanks for the responses. I did find one place and will give them a ring. I'll post back what I find for anyone else that is interested or looking to do some tinkering.