GTA
All Springer/NP/PCP Air Gun Discussion General => Machine Shop Talk & AG Parts Machining => Topic started by: robertr on May 03, 2019, 09:35:06 PM
-
I thought I would post my results using nevoustrigger's DIY Crowning Guide found in this thread. https://www.gatewaytoairguns.org/GTA/index.php?topic=130555 (https://www.gatewaytoairguns.org/GTA/index.php?topic=130555)
Accuracy was not very good with any pellets I used, around an inch at 10 yards, some pellets worse.
Funny thing is it used to shoot AA 16's pretty good but after ordering a new batch of pellets it no longer shoots them well at all. Turns out the new AA's measured at 5.45 mm when they should measure 5.52mm. So much for quality control.
I also used Motorhead's suggestion on inserting a 7/32 drill bit into the choke and found I have what appears to be an oversize barrel, the bit can be inserted without any resistance.
Looking closely I could see what looks like damage to the rifling about 1/4 inch from the end of the barrel and could also feel a bump at that spot when pushing a pellet through the barrel.
So before ordering a new barrel I figured I would give nervousetrigger's method a shot, slightly modified the setup though but followed the directions pretty close. I used an angle grinder with a thin cutoff wheel to slowly chop the barrel.
Sorry for the not so great pics. I think you can see the damage to the rifling in the first pics. The rest are from the start of the process to the end.
My results are encouraging, I can now hit 20 out of 20 paintballs at 25 yards, I would have been lucky to hit one before ;D I am happy with the results, my brother is even happier, he does not have to buy a new barrel.
First time for me working on a barrel, scary at first but was pretty easy in the end or I was just lucky.
-
8) 8) 8)... feels good when ya can get things workin right...
-
8) 8) 8)... feels good when ya can get things workin right...
No kidding Kirby, what a difference a day makes.
-
I really like your lathe. 😉
-
Simple, cheap and creative!!! I give your Idea and execution an A+
Steve
-
I really like your lathe. 😉
As do I.
Simple, cheap and creative!!! I give your Idea and execution an A+
Steve
Thanks, I would have to give nervousetrigger credit for the idea, turned out nice though.
-
Robert, great job sir! I like how you adapted the benchtop drill press and your results speak for themselves.
The closeup picture of the rifling damage is a textbook example of the infamous piloted crowning tool damage. I agree, the hardest part about taking a cutting tool to a barrel is the anxiety of possibly making it worse so the nice thing about Crosman handing you garbage like that is that there’s nothing to lose :) And now you’re ready to take on the next one that comes your way!
-
Thanks Jason, it is a small drill press but a handy tool.
I am lucky I found your thread, that is where I found out about the crowning tool damage, I actually had to chop it twice, I left about 1/16" of bad material the fist time around, after the second chop total amount of barrel removed was 1/4" so still about 1" of choke left.
A new barrel here costs around $80 Canadian so I am very happy it worked. Thanks again.
-
Yep really like the redneck lathe you have there. ;D ;D ;)
Mike
-
Yeah Mike it matches nicely with my Redneck compressor.
-
You know what they say necessity is the mother of all inventions. ;) ;D ;D
Mike