Beeman Rx1 piston seal

[Bayman]

I think my recently acquired 20 cal Beeman RX1 has burned up the piston seal. It was putting out 22-23fpe and now it's lost 30 fps from the average and the extreme Spread jumped from 15 to 50. Does this seem plausible?

[DRose]

Quite possible. You are shooting at the high end of what the rifle was specked for. I had an HW-90 that failed. It was the rear Schrader valve. Bought a seal kit and piston seal just in case. Good thing I did, piston seal was cooked with melted marks on the face of it. I am running it .22 at 20 fpe for now. Very consistent. Dave

[Bayman]

Quite possible. You are shooting at the high end of what the rifle was specked for. I had an HW-90 that failed. It was the rear Schrader valve. Bought a seal kit and piston seal just in case. Good thing I did, piston seal was cooked with melted marks on the face of it. I am running it .22 at 20 fpe for now. Very consistent. Dave

Thanks Dave. Besides the piston seal how was the rest of the seals? Not sure if if I'm going to need the gas ram seals.

[DRose]

The rest of the seals were fine, didn't touch them.

[Bayman]

The rest of the seals were fine, didn't touch them.

Thank you.

[DRose]

Forgot to mention, an adaptor to refill the gas spring to chang out the piston seal.
https://www.bestfittings.co.uk/shop/airgun-charging-equipment/charging-pumps/theoben-weihrauch-hw90-gas-ram-charging-pump-kit/
I used my pcp pump with a quick fill adaptor to recharge. No gauge so I used the chrony to determine how much flbs it was putting out.
No pump no chrony or adaptors could get expensive very quick. The RX is a top of the line springer. Good luck. Dave

[Bayman]

Forgot to mention, an adaptor to refill the gas spring to chang out the piston seal.
https://www.bestfittings.co.uk/shop/airgun-charging-equipment/charging-pumps/theoben-weihrauch-hw90-gas-ram-charging-pump-kit/
I used my pcp pump with a quick fill adaptor to recharge. No gauge so I used the chrony to determine how much flbs it was putting out.
No pump no chrony or adaptors could get expensive very quick. The RX is a top of the line springer. Good luck. Dave

Thanks. I'm wrestling with the buying the whole pump set up. Its a hundred dollars plus shipping from the UK. I have have a freind with a marauder pump and l might just buy the fitting and an adapter if I can figure out which one. There's another gentleman on here that used to have a rx2 and lives locally. I'm hoping he may have something for me. My third option is to have Tom Gore (Vortek) build me a custom spring conversion. It's more money than the other options. All my other Weihrauchs have his kits in them and I love them. Any other tips from your experience with this gun. Would be greatly appreciated. Like which adapter you used.
Thanks again, I really appreciate your help

[Bayman]

My suspicions were right.. Now to. Figure out if I should convert it to spring power.

[DRose]

This was the part needed to hookup to a hp pump with quick fill
https://www.pyramydair.com/product/air-venturi-male-quick-disconnect-1-8-bspp-female-threads-steel-rated?a=3550
You got it apart so you probably can reassemble. YouTube offers a few videos for reassembly. Dave

[Bayman]

This was the part needed to hookup to a hp pump with quick fill
https://www.pyramydair.com/product/air-venturi-male-quick-disconnect-1-8-bspp-female-threads-steel-rated?a=3550
You got it apart so you probably can reassemble. YouTube offers a few videos for reassembly. Dave

Thank you

[tjk]

My suspicions were right.. Now to. Figure out if I should convert it to spring power.

I wouldn’t recommend converting it to spring/strut power. The theoben design is a very efficient power plant and when rebuilt correctly becomes a fantastic shooter. Those groove in your seal are normal. When i had my RX’s i would use jm clear on the orings and the internal inertia slide, and a blend of jm moly and eurotar on the piston itself. Jm used to mak a slightly oversized piston seal that can be fitted to your gun and what application and power you set it ip with. My general rule (rather loosely) with piston guns is ‘the higher the power, the heavier the pellet. If you plan to max out the power with the rx, then dont be too surprised if you fry the seal with lightweight (14 grains or less) pellets. Assuming yours is in .22. The beauty if the rx is that you have alot more freedom of pellet choices and weights without the fear of spring breakage and or premature spring weakening. Power and the seal is really your only major concern!!!

[Bayman]

My suspicions were right.. Now to. Figure out if I should convert it to spring power.

I wouldn’t recommend converting it to spring/strut power. The theoben design is a very efficient power plant and when rebuilt correctly becomes a fantastic shooter. Those groove in your seal are normal. When i had my RX’s i would use jm clear on the orings and the internal inertia slide, and a blend of jm moly and eurotar on the piston itself. Jm used to mak a slightly oversized piston seal that can be fitted to your gun and what application and power you set it ip with. My general rule (rather loosely) with piston guns is ‘the higher the power, the heavier the pellet. If you plan to max out the power with the rx, then dont be too surprised if you fry the seal with lightweight (14 grains or less) pellets. Assuming yours is in .22. The beauty if the rx is that you have alot more freedom of pellet choices and weights without the fear of spring breakage and or premature spring weakening. Power and the seal is really your only major concern!!!

Thanks for the good information. I've nixed the spring conversion idea. I found a bike shock pump and fitting that works for a very reasonable price. I'm in the middle of putting it back together. I removed the stuck inertia weight and honed the inside of the piston. The inertia weight moves now albeit with some drag. I'm reusing all the O-ring seals as they're in good shape. I put a little bit of synthetic oil in the piston. I'm lubing the rest of the gun with Krytox to prevent dieseling. I'm waiting on the piston seals, they should be here mid week. I'm looking forward to get this back together. The gun is a 20 cal. It was shooting about 23 fpe and the first pellets I ran through it were only 10gr. They were Beeman silver bears that the original owner bought with the rifle in 2000. Supporting your too light pellets damage the seal. There's not a lot of choices of pellets in 20 cal. Most of them hang around 14 grains. I'll try running the gun around 20fpe first.