Beeman Sportsman Problem(?)

[Old Bill]

Stopped by a local pawn shop the other day. He had a Beeman Sportsman RS2 Series with only the .177 barrel. Spring break-barrels are not my favorite AG but it was in nice shape with few blems on the wood stock. Asking $65...offered all the cash I had in my wallet, $47, and brought it home. Missing a breech O-ring, so ordered a set of 3 from Amazon. New O-ring installed, test fired and pleased with grouping with both open and scoped sights. BUT, noticed after about 25 shots, the O-ring was shredding a little. Glad I got extra O-rings. Does anyone know if this is indicative of a problem or normal wear and tear? Would appreciate any comments from those in the know. Thanks.

[lizzie]

Certainly does NOT sound like normal wear and tear to me. It's hard to say if it's the O-ring itself, or an issue with the breech and/or mechanics. It could just be that you got cheapie or defective o-rings. Have you changed it out yet to see if another one does the same?

[Old Bill]

Hey, Lizzie, thanks for commenting. Haven't swapped the seal out yet. Will give it more time to see if it gets worse or affects the accuracy. Might have something to do with it not having a seal in when I bought it...like former owner couldn't keep rings in. Anyway, I'm just a plinker and it's a nice rifle; the trigger is smooth with a sharp break and I like the automatic safety. 

[SagaciousKJB]

Did you have to take the barrel out and put it back in at any point? I've shreded one of the rings on my Silver Kodiak X2 ( same basic model ) when changing the barrels because the O-Ring stays in place down there.

Sounds like it's hitting the outer wall of the compression tube too hard to me.  Mine wore out but not until after a few thousand shots and I can see where the rubber slide down the wall.  Maybe check for burrs or something there.

[Old Bill]

Actually I did have the barrel out but that was before I put in the new seal. I'll check for burrs at some point...thanks.

[SagaciousKJB]

This is what mine looks like at about 4-5k shots, but this isn't the original seal.  I think you can see on it where the friction marks are though.




Also that top lip is a pretty hard edge if there's a burr there, or the seal is a little oversized, I could definitely see that tearing it up.

Luckily that spot seems pretty easy to sand with a little emery board or needle file.

Edit:

Looking at your picture again, it might just be the lighting, but I think I can see a burr on your transfer port.

[avator]

Some seals need sized.... If it protrudes too much if will "drag" on closing the barrel. If it sticks out too far you might take a bit off the bottom with some sand paper. While you have it out, make sure someone hasn't shimmed an old one. Anything down in the groove?
Mike Mellick at Flying Dragon enlightened me on sizing breech seals.

[mobilehomer]

I had the same problem on a NP2. I fixed mine by carefully deburring the edges of the o-ring groove. I used the corner of a square stone and worked it on both inner and outer edges at the same time.

[Old Bill]

Thanks KJB, Bill & Ken. I appreciate your comments and suggestions. Will have to do a better inspection of mine and some tweaking. The seals came from airgunorings.com specifically for the Beeman Sportsman, which got me thinking, "Are airgun o-rings a priority item or do most hardware stores carry generic ones?"

[Artie]

I've got a couple of Beeman's, an RS2 & Quiet Tek Ram, both are TF89 clone derivative's of a Spanish Norica Air rifle , the model Marvic Gold I think. Both are fairly accurate and hard hitting, the QTek being a ram version. Yours is pretty much a twin brother.
I did not have an issue with torn/damaged breech seals but they were too hard and compressed, needing relacement. I'm sure my replacement seals (o'rings) came from the local hardware store, though don't specifically recall which one or what size. Either way, hardware or factory version, at some point or even initially, may benefit from shimming to improve sealing. Dental floss or twisted Teflon tape is the field expediant remedy.
POI (point of impact) may be affected by this mod. If the gun's specs are close to where they ought to be, the seal only needs to protrude from the breech block a slight amount, what I call "a little proud". A small machinist straightedge with the breech block held to a back light can verify this. Too proud and you will have inconsistent barrel lock up. Not proud enough and you lose speed.
Often a breech o'ring can be replaced with a not so exact fitting hardware store o'ring and seal just fine with shimming or if your lucky, without modification. Most h/w off the shelf o'rings are 70 Duro, soft enough to expand or contract enough to make do. They may require replacement more often however.
Hope this helps..

[Old Bill]

Thanks, Richard...appreciate the good info. Three seals for $4 plus $3.50 s&h could get old real quick. Think I'll shop the local hardwares.

[Hoosier Daddy]

I found it interesting that my silver RX2 came with a second o-ring. Wondered if that was a sign of common issues. So fay the original is sealing. But it does look like it's got slight shredding similar to yours

[Old Bill]

Seems like if it was an issue (hope not), we'd be hearing more about it, Daddy. Thanks for the reply.

[avator]

I eluded to Mike Mellick earlier... let me elaborate a little..
I traded him a pair of Air Hawks ones for a pair of XS-12. The XS-12 has the o-ring style breech seal. We were talking on the phone sometime later and I mentioned that the seal in one of the XS-12s was beginning to show signs of wear. he sent me a couple replacements, even though I could have used standard O-rings, and told me I may need to adjust them either by shimming or taking a bit off the backs with sand paper. You can do this by making a step in a wood dowel for the o-ring and using sand paper. Maybe 400 or so. same way I do it if fine tuning the BStaley o-ring buffer.

[Old Bill]

Thanks, Bill. Appreciate the follow up and info.

[SagaciousKJB]

So I decided to give this shimming a try since I've had some gremlins on mine that's keeping it from shooting as fast as it should be.  I used dental floss.  I could see it sitting a little more protruded, and when closing the gun I can definitely feel it closing on the spongy seal rather than there being slight metal-to-metal contact.

Gun went from shooting 7.4 gn @ 852 average fps to 877 average fps.

Just to give an idea of how much difference there could be.

[Old Bill]

Thanks, KJB. Good to know. Haven't gotten around to the knitty-gritty yet, but it appears to have good protrusion. My range is typically set up for a max of 50' so excessive velocity isn't that important to me and it seems to do well for my type of plinking. 

[Hoosier Daddy]

Drape a tissue across the breech and see it you have leakage when shot.

[Old Bill]

Good test...will do. Thanks.

[avator]

A small pile of baby powder works pretty good too.