AR Conversion

[Tatershooter]

A friend of mine has a 7.5" 300 BO pistol and is wondering if he can switch the upper to a 9mm and use a mag adapter, then he would have basicly two caliburs. Is it possible or is there more that needs to be changed? I am very knew to the ar pattern rifles myself so I can not advise him. Thanks for any help.

 

[ES44AC]

Probably be better off to build a proper 9mm AR really. PSA has some great deals from time to time. CMMG's 9mm platform looks to be very reliable, but if course it big $$$$.

 

[BigWaylon]

He can use Endomags and not have to install/remove adapter.

With I different upper, I’m assuming he’ll have a 9mm BCG already installed.

Only thing on the lower than should need to be changed is the buffer. Or he could possibly get away with stacking quarters in the buffer tube.

 

[Tucci454]

Apparently you need a heavier buffer though. 5.5 oz minimum is what everyone says... I haven't weighed mine, but its a good deal heavier than the 223/5.56 buffer I pulled out. There's a ton of threads on this around the interwebs. Just dont expect last round bolt hold open to work!

Also, the Mean Arms Endomags seem to work fine as far as feeding goes. I had one failure to feed out of ~200.

 

[Tatershooter]

Thanks guys, will forward this info to him.