[Calvin]

The Czechs adopted the roller block system from the German MG42. Logansdad, you are correct in that H&K uses a similar concept in the USP-series pistols and SMG's.

I didn't know H&K used that in their pistols..I thought it was their rifles, carbines & SMGs

[Big Dog]

NRAJoe, check out this site - they talk about the need for the hard steel rollers. It seems some 9mm barrels come with less rugged rollers, which need to be replaced.

http://makarov.com/cz52/

[NRAJOE]

Thanks Big Dog, cool site, lots of goodies for the CZ and Yugo I bought out there. Can't wait to start playing!

[Klaus]

Calvin, I am fairly sure the USP uses a Browning type lockup. The HK P9s used the roller delayed blowback.

I forgot about the P9s...