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benjamin np2 gone awry

May 28 2017 at 7:22 PM
Bill Rosin  (Login wildbill48)
YF12

have a Benjamin summit np2, same as trail but different stock. Was shooting very well, and if I remember over 800fps with 14.3 grainers. suddenly went sour, accuracy awful, and doesn't "sound" or feel right. and velocity 670. no tissue paper detected leak at breech seal. probably the piston seal? doesn't look too difficult to work on. would also like to put in the brass washers at bbl pivot pin...saw some info that there's an allen head lock screw for the pivot bolt, but don't see it. Is it there somewhere I've overlooked?
thanks!

 
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Quinton Lewis
(Login Domer_Pyle)
YF

I'd guess your gas piston needs to be replaced

May 28 2017, 8:14 PM 

Does only the shot cycle not feel right or does it feel different while cocking also? I'd think if your seal was bad it would be allowing the piston to slam harder than normal and would need to be pretty chewed up for that kind of power loss.

The lock screw you're looking for is on the front of the compression tube fork, stand up the compression tube vertically and it will be right on top

 
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BillE.
(Login garczar)
YF12

Re: benjamin np2 gone awry

May 28 2017, 9:00 PM 

I had one kill a gas-strut. Just my $.02 here but you're better-off just buying a new gun. The gas-spring alone is around 50-60bux plus a seal and then your time. I bought a conventional springer(RWS) that is a WAY nicer gun and much easier to get good groups with. I was not all that impressed with my particular NP2 gun or the scope it came with.
"\"\""

 
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Bill Rosin
(Login wildbill48)
YF12

benjamin np2 gone awry

May 28 2017, 10:04 PM 

thanks for the quick replies. the gun doesn't feel any different when cocking...indicating the gas strut is still ok?
in regards to fixing it...yes, I'm kinda tired of this gun...it's my 3rd in less than 2 yrs..the 1st one was a good shooter til the scope rail fell off. the replacement was not accurate...this one was, til yesterday. but yes, I've got a Diana 34, 460, and an hw97k...all much less trouble and very accurate. but I hate to just trash this benj. so may tear it down and see what's really wrong. thanks.

 
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Quinton Lewis
(Login Domer_Pyle)
YF

It's easy, there's not even a half inch of preload.

May 28 2017, 11:43 PM 

The first NPXL 1100 I had needed the gas spring replaced because velocity dropped a good 100 fps and it didn't feel any different either that I could tell but that may still be your issue. It just seems a little improbable that your piston seal suddenly deteriorated to the point it could cause the problems you describe, couldn't tell you for sure but that's my opinion anyway.

I must have gotten a gem because my Summit has been dime size group at 50 yards with CPHP since I got it and zero problems aside from my first gas spring shooting a little slow which Crosman replaced free as a warranty item. Barely registers on the hold sensitivity scale. Sorry to hear about your luck because mine quickly became my favorite springer, though I've shot a few higher end spring guns I've never owned any but this one feels like it requires the least work to hit what it points at and is stupid quiet

 
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Bill Rosin
(Login wildbill48)
YF12

benjamin np2 gone awry

May 28 2017, 11:53 PM 

thanks for the input...I just took it apart, and the piston seal did have a little chunk torn out of one edge. there was a burr in the compression tube slot. You'd think whoever puts these together could take 20 seconds to file/sand the slot before inserting the piston.
before this happened, I could also, if I did my part and the SD wind wasn't blowing, shoot dime sized groups out to 35 yds. hopefully I can, again.
thanks.

 
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Dan
(Login dan1358)
YF

Re: benjamin np2 gone awry

May 30 2017, 7:57 AM 

Good advise! Glad I read this. I had a Crosman Nitro Venom Dusk.22 with the first edition gas piston, not the NP2. It did the same thing soon after warranty ran out. Would not group any more,one shot sounded different from another.Got rid of it. Thought I might give the NP2 a second chance. Not after reading this. Crosman is becoming disappointing even with their pellets. I have a Hatsan with their gas piston and have had no problems so far and might give Gamo's inert gas technology a try in one of theirs., but done with the Crosman's version.

 
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