GTA
Gateway To Product Reviews => Air Gun Mods and Tunes => : Sgt. Slaughter May 09, 2008, 03:09:38 PM
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I picked up a Crosman Quest(.177) as my first air rifle around Christmas time for some small game hunting and just for the pleasure of shooting at targets. I finally am able to spend some time shooting again since college is over for now, but while choreographing the rifle the other day, I found that the velocity was on average 640fps with a deviation of 20fps. From the large deviation and low velocity I believe the piston seal was at fault due to the rough inner walls of the receiver (less than 2000 rounds have been fired.) I've read about deburring the receiver and sanding the piston as well, but noticed that if using a brake hone it is recommended to use stones with a 240grit. My question is why is 240grit recommended rather than a finer grit such as 400 or higher? I assume that the reason is so that the lubricant used can latch onto the piston and inner receiver better opposed to a higher grit, but I just wanted someone to give me a definite answer (I also plan on using a flex-hone rather than a brake cylinder hone.) Since I will be replacing the seal, I've gotten very interested in tuning my Quest. I've read numerous sites and information(a large portion coming from here.) I have a Sherline lathe, and experience making custom parts for pneumatic applications so I'd really like to start designing a new top hat first. From what I've read though, some B-19s and other springers don't always have a top hat. Is there any purpose for a top hat other than as a minor spring guide? Would making a custom top hat out of a lighter/heavier material benefit the Quest in any way?
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Jason, I think you may find a broken spring, instead of a bad seal. Cause depending on the shot count, 20fps deviation is not as bad as 640fps average, that's too low for that rifle. As far as honing the cylinder I use a 3/8" wooden dowel, with a split in it, to accept a piece of 320-600grt paper, a homemade flapper wheel type. HTH some and Welcome to a wonderful forum.
Mike
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Thanks for the welcome Mike. I checked the spring but it seems fine. Thanks for the tip on the flapper wheel as well.