Canadian Airgun Forum

I thought I would be better off to ask first before ordering. I have a early '90s Webley Vulcan that was not used very much until this past winter. I recently chronographed the gun to see how consistent the velocity was and to confirm my belief that it was definitely sub 12 fpe. I shot 50 pellets over the chrony and found that the velocity started at 786 fps with JSB Express (7.9 gr) and then started to fall, slowly over the first 15 shots, and then consistently down to 725 fps by the time I shot the fiftieth. I was not expecting the power/velocity to drop so much.

I have an HW77k that is shooting with less velocity than it should (it is a full power rifle that is now shooting at about 12fpe) and the good folks here at CAF have suggested that the gun probably needs a new breech seal, which I've ordered and should be replacing in time to try out the 77 on the weekend. I am therefore thinking that the problem with the Webley's power/velocity loss is also due to the breech seal.

So my question is does it sound like a breech seal problem? I'm going to order a new seal (or two or three) from the U.K. Should I be thinking about ordering something else, like a piston seal, perhaps?