Hop-up Bucking

I just opened up my M4 to try and put in the small metal ring (a barrel spacer?) that I didn't put in when I installed my TBB. When I pulled out the TBB, my bucking came off kind of weird, and that little piece that is why hop up works fell out (b/c I forgot to lower my hop up setting before taking off the barrel). Now I need new bucking (the TBB goes through the bucking), and the little ring I wanted to put on doesn't fit on my new barrel (it is REALLY thick for some reason, my SPR flash hider doesn't fit over it...). So:

I need new bucking, and have no idea what is good kind/manufacturer. Are they all the same, and recommendations if not?

Thanks.

I've heard good things about Systema buckings. I think they're also one of the cheaper quality buckings on the market.

Cheaper quality? That was the first kind I looked at on AGI...

Go with Systema always....all my buckings ive changed out are from them and they work great.

Ah bad wording, sorry. I meant it's one of the cheaper (price wise) high quality buckings.

Oh, okay! I'll probably buy one this week.