Beeman Beeman R-7 .20 cal rebuild….. results….?

You should notice and increase in velocity as the piston seal wears in. Did you verify that all original parts and pieces are accounted for with the new install? You didn't forget the top hat, power spacer or any other part going to the front or back side of the spring?

joeayv said:

So I have an R-7 .20 cal from 1993. I bought it used a few years ago. Smooth as glass cocking it. It shoots well. But I wanted to rebuild it like many of my other springers.
I got a Vortek pg-4 kit about 2 years ago. but never got around to doing the job.
as I’m home sick as a dog. I decided to do the test. I was and am a little dumbfounded with the results. as I know all spring guns are different,some better then others etc.etc….
but I actually lost power. although I’ve only put around 50 shots through it. I don’t expect any major improvement in velocity. The gun is quieter for sure and the shot cycle is better. I put pg-4 kit in my r-10 and I gained over 110 fps on that gun. I honestly expected to gain about 75 fps. All the internals are original and stock. 32 years old…
anyway… here are some pictures and results.just an FYI for my fellow airgunners.

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Wow! About 35 fps with the 11.42's, but not to bad with the 13.73's. It may come around during break in, but you may not even notice any loss while shooting.

How did you fit the new seal? I feel too tight a seal will bog things down .

Too loose ( and loose / undersize pellets) can slam . Notice the transfer port marks in your old seal.

Too tight or too loose but feel of jusssssstttt right .

If this helps any


Maybe some breakin will do the trick not like your 100fps low depending of your chrony is at the muzzle or 10 yards away ..

joeayv said:

Thank you for the info. I’m going to mount up the scope and shoot it for a while. I’ll do another reading after a tin or 2…

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Do at least 10 shot string . Sometimes as the shot count increases the seal could bog more or show things slowing down as your shot count goes up .

That chart kinda gives you a ball park figure to gauge by +/- . Not solid gospel..lol

I’ve got a R-7 .20 with a Vortek pg4 and it’s a hammer. Seal sizing is key with them as well as lube removal in the inner springs. That being said it is a tad snappy , there is immediate pre load at barrel break when loading.
550 fps with 11.4 Ftt.

joeayv said:

Well there is the 70+ fps I was looking for. I didn’t size the seal. But the cocking effort feels tha same from the old spring to the new vortek spring. Maybe after 500-1000 shots it will pick up a few fps. But I’m not sure it will.

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It may get 10 fps. But it sure is hell is not gonna get 70. If the seals snug. Was the Vac seal snug?
It needs to be on the fine line to get the most of the tiny 25 mm short stroke.

No , my tube was actually on the larger side of 25 mm .. That being said Tom changes the kits so often that the spring you have may not be the same. Coil count and such

Like I said, they have such a short stroke and small tube you need to make sure to get all you can out of them.
Snug is having to push with some effort. The old adage of it should fall down by the weight of the piston may work with thin lined parachutes but not cup seals..

It should slide easy with smooth feel and build immediate pressure on port plug.
Breech seal may need checking. If it’s flat. should at least see 500to 510. Min ..

joeayv said:

Did you ever crony your .20 cal hw-30.

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I have lost count of shots fired in this HW30. At one time it was at 11 tins, likely 15 or more tins with no internal maintenance.

Dont think i never took one back apart a few times to take that little bit more off the seal after testing .

But remember ... You can take a little off as you go but you cant put it back on if you go too far . I usually throw at min 2 seals in the order .

One to use anf one as a just in case oops seal.

That fit can be explained a lot but it comes down to a personal experience " feel" , but a good chrony at the muzzle tell all in the end

Hateful McNasty said:

Dont think i never took one back apart a few times to take that little bit more off the seal after testing .

But remember ... You can take a little off as you go but you cant put it back on if you go too far . I usually throw at min 2 seals in the order .

One to use anf one as a just in case oops seal

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Sizing Vac seals is tricky as the material is odd and Tom puts a small leading edge of them ( something I’ve never been a fan of ) size them from the face for better results. Without a lathe it’s a tough job. Can it be done ,Yes .. some had worth with a flat surface and 180aluminum oxide paper and keep it flat to the face.

A.G.R said:

Sizing Vac seals is tricky as the material is odd and Tom puts a small leading edge of them ( something I’ve never been a fan of ) size them from the face for better results. Without a lathe it’s a tough job. Can it be done ,Yes .. some had worth with a flat surface and 180aluminum oxide paper and keep it flat to the face.

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Maybe that leading edge is ehat you got to ware in for that usage sizing ?

I use ARH stuff for the all in one order thing . Lol ..

Hateful McNasty said:

Maybe that leading edge is ehat you got to ware in for that usage sizing ?

I use ARH stuff for the all in one order thing . Lol ..

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Nope it’s a los of tiny volume.. albeit tiny it’s not the loss issue. it’s the seal sizing. They are designed to fit snugger and burn in. It’s a manufacture % game as every tube is different and if thats Built in leeway. That and they have no sharp edges to grab threads and holes for The average Joe installer. The more powerful guns like R1/ R9 that have the spring power to heat them , compression size them in. Smaller guns won’t generate the needed heat and friction to size down. Macarri just plain out builds what he wants and tells you strait out. YOU NEED TO SIZE THEM. (Which I have no issue with)
I make 90% of my seals for my big power guns and all 27 mm Tommy /Longbow guns.

I can not take any credit as it’s a direct copy of the Venom power pulse seal. They are a different breed for the leading edge is sharp and the way it fits is much different. when done right they act More like a O ring with out the O ring shot cycle.

The VAC SEAL MAY LOOK ALIKE ,BUT IT SEALS MUCH DIFFERENTLY..
Air is pushed against the lip and the micro gap forces the seal to expand. (it’s why after break in some Vac seals will not test positive for psi at the port yet shoot fantastic as they need constant psi to open.
At the end of the stroke you get a pulse blast from the gap.

Power pulse Venom seals were sharp to the end and sealed with a snug er fit that had a 1 mm contact point ,( you can see the smoother area in the pics on the edge) they build immediate psi at moving. (Just like a O ring ) , the angle onnthe cup is steeper and its a tad deeper for a bigger pulse. (Yes I’ve tested them deeper and it’s a down hill loss). F
They are no longer made as ,well there is no more Venom/V-Mach. So I make my own , then again I make my own guns too.

joeayv said:

So I have an R-7 .20 cal from 1993. I bought it used a few years ago. Smooth as glass cocking it. It shoots well. But I wanted to rebuild it like many of my other springers.
I got a Vortek pg-4 kit about 2 years ago. but never got around to doing the job.
as I’m home sick as a dog. I decided to do the test. I was and am a little dumbfounded with the results. as I know all spring guns are different,some better then others etc.etc….
but I actually lost power. although I’ve only put around 50 shots through it. I don’t expect any major improvement in velocity. The gun is quieter for sure and the shot cycle is better. I put pg-4 kit in my r-10 and I gained over 110 fps on that gun. I honestly expected to gain about 75 fps. All the internals are original and stock. 32 years old…
anyway… here are some pictures and results.just an FYI for my fellow airgunners.

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I will take smoother cycle over FPS any day .

beerthief said:

I will take smoother cycle over FPS any day .

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Agreed. But it’s a R7. You don’t want to beat the pellet to the target while checking ..

That being said , power with out a racy is a faster miss

When I was building big guns for people they insisted this amount of power .. I said WHY?
down range 750fps is all you need to 40 yards with it sighted in at 25.