RX2 Power

[PakProtector]

hey-Hey!!!,
I finally worked up the courage to let some air out of my 20 cal RX2's ram to bring it down to 19 FPE, or about 790 with Exacts. I had presence of mind to take a few shots across the chrony to baseline it. Last time I had the chrony out it was shooting 840 with same pellet. It was now shooting at my target speed.

How to determine if this is the ram leaking slowly, or if I have a bit of seal damage? It is consistent at 790 fps( maybe 7 fps ES ).
cheers,
Douglas

[tjk]

Has it been tuned or pure stock?

[PakProtector]

Has it been tuned or pure stock?

It is stock. Acquired new just shy of a year ago. It shot exacts at 890 when I first got it, and then settled down to 840 fairly quickly, and stayed there for a while. At least to mid-fall it was shooting around 840.

I guess I should have added the caveat, 'without tearing it down'...
cheers,
Douglas

[tjk]

How old is your rifle. Do you know the approximate date of manufacture? Some factory guns have lasted the test of many years without power decline while some have not. IMO, these guns shoot much better and a lot more consistantly with a Properly sized JM piston seal. A bad/damaged seal or a poorly seated seal installed can result in inconsistant velocities. If shooting farely consistant velocities, I would suspect the oring ram seals have dried some of even started to dry-rot if your rifle has some age on it. Easy fix with a JM moly and  clear tar/euro-grease. New orings and a seal are easy to come by too.

[itbvolks]

Good to hear. I pulled some air out of my setup as well. I noticed smoother cycling and reduced cooking effort and less hold sensitivity. Mines still shooting pretty hot so planning on pulling some more out.

Unfortunately my RX 2 took out my Leupold EFR so it's off for repair and probably M1 target turrets...

Tom ,

Curious what JM seal option you prefer? The parachute version or the newer 426 cupped face version? I think I'm going to try the new 426 version and bore mic the comp tube. Probably hit it with a flexible ball hone and clean her right up. Should give a nice uniform finish for lube to adhere too. Then I can properly size the tube/seal interface as well...

[PakProtector]

I have a 426 seal in hand. I tell you I don't like two of its features. One being the cup that will lower the compression ratio, and the other being the seal is what is going to get crashed up against the end of the compression chamber. I could bee missing something, but that's how it looks to me right now.
cheers,
Douglas

[itbvolks]

If I had to guess, the parachute seal has a pretty significant amount of volume tied up in the seal cup/lip of the parachute.the slightly cupped version of the 426 might not be as deep as you might think volume wise.

I think if the factory comp tube is quality and in good shape and the tolerances are good, I think it could make great power. I am concerned with a poor fit causing issues with quality of seal depending on fit. It's not terribly spent to try so I'll poorly order one to try. I've got baseline velocity numbers to compare too so I'll know pretty quick...

Anyone have any other tuning info for these gas ram guns? These are pretty simple compared to a springer from a shot cycle standpoint.

I would love a gun that likes FTTs at ~19-20 fpe (900 fps). To me that's, the ideal setup for .20 as it offers flat shooting and good energy.

[Nikoman]

I just checked my paperwork for my RX-1 and Beeman did a super gas charge to it many years ago. Among the paperwork I found a tag showing the Chrony results and a 5 shot group with the gun's serial number stamped on it.
In stock form, mine was shooting a harsh 21-22fpe. The shot cycle was harsh and the cocking effort was high. I sent it in because I thought it was ridiculous that my Crow Magnum was waaaay smoother and produced 12fpe more than the RX-1 at the muzzle.
After the super gas charge, the rifle came back transformed with upgraded stock screws (from Beeman) and the pressure was only slightly over 18fpe, knocking on the door of 19fpe with certain pellets. Anyways, the cocking effort is MUCH lighter and the shot cycle is basically R7'ish. The accuracy is ridiculous and the gun is so easy to shoot. It has not lost any pressure since the October 1997 super gas charge. I've taken thousands and thousands of shots with it over the years and it's still going strong. I just pulled the Leupold EFR off it last week to send back to service, the lubes basically dried out and the scope zoom and focus knobs need a little lubing but other than that there's no damage to the scope whatsoever. I could still use it with the tight zoom ring and the loose focus knob but why not take advantage of a lifetime warranty.
So what I'm trying to say is don't worry about removing even more gas out of your RX rifles, they only get smoother and more accurate - at least mine did.

It's pretty cool to find all my receipts and paperwork, here's the group shot by the Beeman techs after the tune:
Target is actual size.

[palonej]

My God Niko......that lady sounds like a keeper!!!!

[Nikoman]

My God Niko......that lady sounds like a keeper!!!!

Yeah she sure is, Joe.
I've been neglecting her lately but I plan on giving her some needed love and attention as soon as I get the Leupy back. I just checked my records and that Leupold is from 1994 so it's almost 20 years old!
As soon as I get the combo back together I'm taking this 'ol Fraulein for some real hunting like old times. Great rifle for coons and possums.

[itbvolks]

Has it been tuned or pure stock?

It is stock. Acquired new just shy of a year ago. It shot exacts at 890 when I first got it, and then settled down to 840 fairly quickly, and stayed there for a while. At least to mid-fall it was shooting around 840.

I guess I should have added the caveat, 'without tearing it down'...
cheers,
Douglas

Would be interesting to know if your having any issues with a ram seal...