. 20 caliber / 5mm beeman rx1 (weihrauch model 90)
. . excellent quality. excellent power. but very heavy - 10-11 lbs. it's an older model, so i attributed the lesser than expected velocity to worn parts. the hole in the back of the tube allows for a hand-held pump which one can fasten to add pressure into the gas ram. it was chronographing 800 fps w/ 12.8 grain crow magnums. strangely enough, this gun loved those huge hollow points. it would cloverleaf at 50 yards from bench rest w/ crowmags. it liked the crosman premiers too, but shot much slower w/ those. these are great airguns, but you'd need to be arnold swartzenegger to hunt with it in the field. i took a photo of the theoben engraving on the breech block. theoben gas rams are the best i have used. - raneman. - 11-20-13.