GTA
Airguns by Make and Model => Benjamin Airguns => Topic started by: RGTools on September 03, 2015, 07:25:07 PM
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Hello. I got this gun for ground-squirrels, a pernicious problem on my farm and I have noticed a few issues that perhaps you can help with.
1. I did remove the paint from the barrel using all finish stripper. This did improve the 12yrd group from 1.5" to 5/8" (pretty big improvement). not an issue but worth mentioning now so it's not rehashed. P.S. it offends my very soul that Crosman has not corrected this on the manufacturing side.
2. After 12 yards, even from a rest, I am having trouble making decent 1" groups. I need 20yrds, but would prefer 35yrds. I have a Straight Shooters Pellet pack on the way to see if this is a "right pellet" issue, but my question is this: what distance should I really expect this gun to punch a quarter?
3. After a long shooting session trying to sight in my iron sights (my first set of scope rings were too low and being replaced by the seller) the gun started venting air on the 3rd pump or so. I let the gun cool off and the problem went away, only to return sooner next time I shot more than a few rounds. I am thinking I warped a seal with heat...would you agree, and where to I get replacement parts?
Thanks for the input.
2 squirrels taken out this week, but half of those were in a trap.
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Also how do I post pics on this forum?
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5/8 groups ain't bad, but compared to mine not great. So I'm gonna say you haven't found the right pellet yet. I'm gonna go out on a limb and say you are using the Crosman HP? They are known to loose stability once you get out pass 15 yards. Try a good domed pellet CPUM, JSB 15.89, H&N FTT 14.66 etc. Now, look up (North Country Girl) something like that and she does some shots on paper from as far as 50yards. For the 392 for ground squirrels I'd keep it inside 30 yards.
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She doesn't do the 392. She uses a 397 and a blue streak she did 50 yards groups at. They are impressive!!!
http://www.gatewaytoairguns.org/GTA/index.php?action=profile;area=showposts;sa=topics;u=17580 (http://www.gatewaytoairguns.org/GTA/index.php?action=profile;area=showposts;sa=topics;u=17580)
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She doesn't do the 392. She uses a 397 and a blue streak she did 50 yards groups at. They are impressive!!!
http://www.gatewaytoairguns.org/GTA/index.php?action=profile;area=showposts;sa=topics;u=17580 (http://www.gatewaytoairguns.org/GTA/index.php?action=profile;area=showposts;sa=topics;u=17580)
Holy cow those are some good groups!!! That is about what I am looking for. You were correct about the Crosman HP's by the way. I can't seem to find the domed premiers in my area. So I will report on my results on thePellet Pack when it get here.
Unfortunately the leak is now there to stay. So I assume I will have to do a re-seal before shooting again. Tell me I am not the only guy to burn out this gun in less that 150 rounds.
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Try cocking it first. Then start pumping, you shouldn't be having venting air during pumping. When you saying "venting" where are u hearing the air, out the barrel?
Now will it continue to hiss air out until it's out of air? Does it only hiss a breath of air in the process of each pump?
Is this a brand new rifle? If so u should send it back. By the size of your groups it sounds like you have a good one accuracy wise. So u risk a chance of getting a bad accuracy one. That u will have to return too. So your choice if you have a choice.
Now when you used the stripper for the paint. Did you make sure it didn't go down the barrel to the TP? You should have either stuffed a ball of paper beyond the paint at the muzzle to prevent this or you could have rolled up a shirt or towel and left it under the shoulder stock to keep stripper from traveling down the barrel to TP.
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Unfortunately the leak is now there to stay. So I assume I will have to do a re-seal before shooting again. Tell me I am not the only guy to burn out this gun in less that 150 rounds.
I think the only part you can 'burn up' is the pump cup, and that should not happen if you are oiling the rifle like you're supposed to.
You did not mention when you bought the rifle. But if it was a year or two back, or if it was old stock, it may have the aluminum valve cartridge. Even if it has a brass valve, best thing would be to just order a new valve assembly and a pump cup directly from Crosman for like 5 or 6 bucks.
If your rifle has the aluminum, just toss it 'cause it's not worth rebuilding. But if it has brass then you can open it up and see what went wrong. If you hear hissing from the breech, most likely the outlet valve is the one not sealing.
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Try cocking it first. Then start pumping, you shouldn't be having venting air during pumping. When you saying "venting" where are u hearing the air, out the barrel?
Now will it continue to hiss air out until it's out of air? Does it only hiss a breath of air in the process of each pump?
Is this a brand new rifle? If so u should send it back. By the size of your groups it sounds like you have a good one accuracy wise. So u risk a chance of getting a bad accuracy one. That u will have to return too. So your choice if you have a choice.
Now when you used the stripper for the paint. Did you make sure it didn't go down the barrel to the TP? You should have either stuffed a ball of paper beyond the paint at the muzzle to prevent this or you could have rolled up a shirt or towel and left it under the shoulder stock to keep stripper from traveling down the barrel to TP.
I was careful not to get any of the gunk in the chamber (I stuffed a few cotton balls in the barrel to be sure). The cocking trick did not work.
In answer to a few other questions. I got it new from Baker Airguns...I spoke to Dennis there and we are swapping out the seals. I have been impressed with the way he handles business so far. I will let you know how that goes.
And yes the air is coming from the barrel.
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Keep us updated. I'm guessing it's the valve stem o-ring
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What do you mean "venting air"?
Reason I ask is I got a new 392 last fall and it starting leaking around the outer valve o-ring after about 50 or so shots.
It would usually pump fine until around pump 3, then it would leak the 4th pump around that outer o-ring and work its way between the valve and
breech exhaust hole and leak. Crazy thing is, if you had a pellet in the breech and the bolt closed, it would actually FIRE the pellet out the barrel.
This was really surprising if your not ready for it!!
I took out the valve and replaced the outer o-ring with a new one and its worked great ever since.
Just to be on the safe side, It taught me to "load" the pellet and close the bolt last, after you've pumped the gun.
Thanks
Ray
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Keep us updated. I'm guessing it's the valve stem o-ring
I have it ripped apart on my work bench right now. I am more impressed with this gun having seen the guts of it, it's a simple, robust design. You are correct about the valve stem, it was blown out on one side, so now I am waiting for the replacement. Also had a ring in the back of the valve on the outside chipped too, I figure this could account for a small loss in fps.
Slashed my thumb trying to get the rubber out of the valve stem in the hopes that I could replace that and have a spare, I will let you know if that works or not...oh and my thumb is fine, because I am a first aid pro.
I would love to show pictures (of the valve not my thumb) but I have not figured out how to do so with success on this site. Normally I try and it eats my post. What am I doing wrong?
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What do you mean "venting air"?
Reason I ask is I got a new 392 last fall and it starting leaking around the outer valve o-ring after about 50 or so shots.
It would usually pump fine until around pump 3, then it would leak the 4th pump around that outer o-ring and work its way between the valve and
breech exhaust hole and leak. Crazy thing is, if you had a pellet in the breech and the bolt closed, it would actually FIRE the pellet out the barrel.
This was really surprising if your not ready for it!!
I took out the valve and replaced the outer o-ring with a new one and its worked great ever since.
Just to be on the safe side, It taught me to "load" the pellet and close the bolt last, after you've pumped the gun.
Thanks
Ray
I could not agree more with that last part Ray. When pumping the gun it is near impossible to point in a "surely safe" direction.
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RGTools, I think you need 15 posts or something like that before you can put up pics. Good luck with your rifle.
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Sounds like you're on your way, just make sure to keep her well lubed after the reseal and you should be good to go.
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Make a small investment & buy a bottle of Secret Sauce to keep your pumper lubed & healthy.
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In the mean time until parts come in you can get a replacement o-ring on that valve stem from the hardware store. I did for my 76 Dan yours blew out so u don't need to cut that out. Just bring the stem and find one that fits. I think I picked the 3rd smallest one they had. Here is my thread little down further u can see my valve stem minus the oring: http://www.gatewaytoairguns.org/GTA/index.php?topic=95021.msg889161#msg889161 (http://www.gatewaytoairguns.org/GTA/index.php?topic=95021.msg889161#msg889161)
Oh and forgetting pictures up. I take a picture of something, edit out background some, then take a screen shot of it. The screen shot picture is generally under the 200kb limit
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Make a small investment & buy a bottle of Secret Sauce to keep your pumper lubed & healthy.
Actually I had a question or two relating to this.
1. I was planning on using MolyKote 111, or Pure Divers Silicone for the O-Rings. Any preference out of the two? Cautions against? Reasons for going to Mac1...
2. I see some Kits on Mac1's website This one in particular caught my eye...mac1airgunshop.com/sheridan-rocker-bolt-lug-p/m1bilevki.htm (I would have linked it but I am not allowed to yet)
but I don't see anything to do with the valve. Is this a steroid kit, part of a steroid kit, or does the gun have to be sent to Mac1 to be "steroided"? I figure since I have the gun in pieces it may be nice to do this myself if possible.
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That tool is for removing the bolt. The little hex head screw that goes into the bolt, needs to be removed so you can slide out bolt from back of breech.
I have no clue about the things u listed. Use what u wanna use. I've only used Pellgunoil, ND motor oil, and SS.
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Forgot I had the pic of my bolt tool. Hardware store nut, wing nut, threaded bolt with (1/8?)?hex end.
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Have used many different oils/lubes on older Sheridans and Benjamins, including but not limited to those mentioned here, and find that the Secret Sauce is 'slipperier' than all the rest.
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Have used many different oils/lubes on older Sheridans and Benjamins, including but not limited to those mentioned here, and find that the Secret Sauce is 'slipperier' than all the rest.
Good to know, I will probably get some.
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Got my seal kit yesterday. Swapped out the valve stem and the rearmost o-ring. I used pellgun oil since it came with the kit. Seems to be working fine. Now I just have to sight the thing back in (had to swap out the scope rings because the initial ones I got were the wrong height and rubbed on both the bolt and the front sight).
First time in my life, I couldn't get on the paper at 12yrds. I reset the scope near factory zero and did a "redneck boresight" last night. I'll let you know if it worked later.
Here is a picture of my rig before repair. Sorry for the terrible cropping job-pre coffee is not the time to teach yourself photoshop.
(http://IMG1110Edited4.jpg)
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OH HECK YEAH!!!!!!!!!!!!!!!!!!!!!!!!
Got the repairs done and the gun sighted in. I will do a more detailed post in the hunting gate, but this gun is slinging lead right where I want it.
Here is a pic of the redone mount and a target shot I took freehand at a random range (~18yrds) to see if I'd actually gotten the scope dialed in right for my quarry...I would say yes.