I had bad accuracy,only thing i did was replace the nitro piston, and now 30 yard pester all day long, don't think I adjusted or modified anything else , on purpose any how here is the listing for the piston I used.http://www.airgunwarehouseinc.com/py-a-3830.html I even re-used the original piston seal, hmmm speaking of seals how does the breach seal look? I hope things work out there Manny
I've never owned one of Crosman's NP offerings but if the barrels are of similar origin as their B-19 clones, you could try touching up the crown.Every one of the Crosman break barrels I've owned became much better after giving their crowns a little attention.Blue
Yeah, no problem, it's pretty easy once you get a feel for it.I use a brass round read bolt with a slot. You want brass because it's soft. Pick a round head that will give you the profile of your crown, and you need the slot to hold a little of your lapping compound. I've used everything from 120 grit carbide lapping compound to toothpaste to red and white jewelers rouge. Sometimes I use progressive grits of wet/dry paper just held onto the bolt head and worked by hand. In fact, now that I'm thinking about it, I usually finish my crown this way. I'll hold a piece of 600 to 1000 grit paper over the bolt for the final polishing round.Stick a q-tip or a pellet or something in the barrel just past the crown to keep grit from getting down into the barrel/action, push it out with a dowel or rod when you're done or checking progress.I usually just chuck the brass screw/bolt into my cordless drill, smear some lapping compound on the bolt head, then work the drill with one hand while holding the barrel with the other (I think slower is better than fast). The key is to "wobble" the drill around as you're lapping. I forget why but if you don't wobble the drill, you'll get an uneven crown. I'll alternate between a small wobble and a large wobble then reverse the drill and do the same thing just don't try to hold the drill straight down the bore the whole time.Repeat.If you want a super polished crown just keep going with increasing grits. I tend to use a different bolt for each grit and replace the bolts frequently. The bolt heat profile will wear down and if you're using different bolts for different grits the profile's eventually won't match up when you change for the next grit.I usually work the crown spending a few minutes with each grit before moving up then I check progress. I'll clean out the end of the barrel, check for burrs with a q-tip then inspect with a light and magnifying glass. If I can see something that needs attention I go back to the screws and repeat the process. If everything looks good, I shoot a few groups to see if there's improvement. If it's good enough, I'm done. If it's better but still not where I want it, I'll go back to the screws repeat the process and test again until it's where I want it or I know it'll never get there.You can REALLY get into it and completely re-do to crown or you can just give it a light touch up with the finer grits. The process is pretty easy so even if you REALLY get into it it doesn't take that long.Bottom pic is the bolts I use for my .22 barrels, I have the same setup for my .177 barrels.Blue
Oh man, screw sizes sometimes mess with my head and I always end up having to bring a "representative" to the hardware store with me for reference. I think I use brass round head slotted machine bolts so poke around in that section. I measured the diameter of the heads of the bolts in my .177 tin and it looks like they're 1/4" wide so look for something around that and it should work. The thread doesn't matter it gets chucked in the collet.The larger the head, the greater the radius and the further you'll have to grind out the meat of the barrel until you reach the edge of the rifling. Kind of like resetting a knifes edge to a shallower angle, you have to grind away the hump from the previously steeper angle before you actually get the the edge.White toothpaste usually has a grit like aluminum oxide so it can work for polishing. You might try an auto store and ask what they have for valve lapping/grinding and other rubbing compounds. They should at least have a course and fine offering. The 120 grit carbide compound I had was for lapping lawnmower blades, not sure where I got it. I found that unless the hardware store had an automotive section they didn't have much. I ended up at an auto store anyway because they were the only ones who carried the high grit wet/dry papers that I wanted for polishing metal (I think they were around the paint and finish supplies).Somebody mentioned the pivot bushings which could also be part of the problem. I remember people would experience them wearing out over time and replacing them with metal. I think people were recommending getting (bronze maybe?) washers and having to sand and size them to get them to fit, but I also thought they stopped using the ones that were wearing out. I could be wrong. Either way make sure the stock screws are tight and the pivot bolt is tight enough to hold the barrel at any angle without it falling but not so tight it's binding up. I know, I hate those vague "just Goldilocks it" directions too.Blue
Hey thanks,so a screw that is in between a .22 and .25 cal head should do.my Ace has an auto section and also there's a Napa in town too thanks again, much appreciate it.........doesn't the Charlie Da Tuna site sell bushings for Crosman rifles ?
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