Originally Posted by
flatrajectory
So, first co2 bulb in yesterday. In a cool workshop ( 9 deg.c ).
First few 6 yard groups were pretty poor 2.5" -3" and velocity all over the place . First 6 shots went from 425 fps down to 382 fps. Several groups later......much the same. However...... I knew I would have problems from the off.
I had great difficulty piercing the co2 bulb, so much so that I was worried I might strip the thread I had to tighten it so much. I knew from the velocity figures that the bulb had barely pierced, which always shows up with a rapid velocity drop between shots. In the end I unwound the bulb and dumped the remaining gas. Sure enough the hole in the bulb was the size of a needle tip. I was using Crosman co2 bulb.
Fresh start today. Umarex bulb in and pierced straight away no problem. Freezing cold and foggy outside, inside my workshop only 7 deg.c.
First 6 yard group l.5" that's more like it. Second group 1.25"....... even better. Third and fourth group all about the 1.5" mark.
Fps around the 395 - 405 fps mark in the cold atmosphere. It should see 425 fps on a warm day.
At 10 yards ( I was standing outside shooting in to the workshop) I shot two groups of 2" -2.5" .
Am I happy with my mk.6........oh yes.
I will probably convert it to 6mm though in the near future as I much prefer that calibre for informal can bashing.
Pete.