The Benjamin 250 is one of three pistols that make up the 250 line of air guns. Here is how they break down: 250 is a .175 BB pistol 252 is a .22 caliber pellet pistol 257 is a .177 caliber pistol. The problem is finding .175 BB's today most all BB are .177 caliber. I've heard that BB are still .175 only the caliber of the barrel has moved up to .177 to accommodate pellets. I suggest you just try one.
Find a good gun smith.
What Model 51 pistol or a rifle and what model?
H&K USP45, hands down. Imo its the best designed pistol in the market 2day. Great looking, reliable and accurate. My cousin has one as service pistol and it has never jammed.
Yes.
Follow the instructions in the owner's manual
Find a gunsmith and ask for help
Best left to a gunsmith.
The link at the bottom of this page will take you to the Ruger website for your pistol. You can download the owner's manual for your pistol, which includes instructions on assembly and maintenance.
Ask a gunsmith for help
I THINK you mean Ortgies. No manual available, would ask a gunsmith for instructions on this one.
if a pistol, tnen the same way as the military 45 cal pistol