So far, I've only seen one sportline with the same internals as the proline, that's the ICS mp5's. However, Ive seen several players with CA and G&G sportline m4's, and they've all really liked them, for the most part. I got a CA proline m4 back in '05. Did a few basic upgrades, (spring, inner barrel, piston & piston head) and ran a 30amp 10.8x3000 nunchuck in it. One moose of a battery, I only burned up one trigger in the 3 years I owned it. Also, G&G's sportline mp5 is a very good value for the price. When we first started playing, UTG had an mp5 on the market that was only $120, came with two super high cap mags, a nice 3 point sling, and a double railed riser mount. Internals were nothing to shout about, but they took a fair amount of the abuse we gave 'em, and they were marui compatible. Put this alongside the $40-50 in accessories that came with it, and it was the best bang for your buck deal I've seen. I can't imagine why they didn't stick around.
