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Fenman power issue

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Rog1415

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So I've decided that i either need to reduce the power on my late model Fenman profile or sell it, after a 3 hour session down the range I looked like i'd just walked out of the gym. The guns sub 12 ft lbs and very accurate but i've got to the age where its just not that much fun to shoot anymore. It also feels like its under loads of stress.

Is it something that's easy to do and if so how?
 
Rog1415 said:
So I've decided that i either need to reduce the power on my late model Fenman profile or sell it, after a 3 hour session down the range I looked like i'd just walked out of the gym. The guns sub 12 ft lbs and very accurate but i've got to the age where its just not that much fun to shoot anymore. It also feels like its under loads of stress.

Is it something that's easy to do and if so how?
Click to expand...
Don't you give a tap to the schrader valve stem @ rear of cylinder , letting out a bit of air from the ram, thus reducing power ? Kinda like letting air out of a tyre.
 
Rog1415 said:
So I've decided that i either need to reduce the power on my late model Fenman profile or sell it, after a 3 hour session down the range I looked like i'd just walked out of the gym. The guns sub 12 ft lbs and very accurate but i've got to the age where its just not that much fun to shoot anymore. It also feels like its under loads of stress.

Is it something that's easy to do and if so how?
Click to expand...
As Chris says above, lightest prod of the modified schrader to reduce the ram pressure ... you will need an adaptor and Slim Jim / stirrup pump to top it up if you go too far.
 
chouchin66 said:
Don't you give a tap to the schrader valve stem @ rear of cylinder , letting out a bit of air from the ram, thus reducing power ? Kinda like letting air out of a tyre.
Click to expand...
You do but very gentle taps & it often causes the valve seal to fail on older guns like the HW 90 I restored for a mate. New high pressure schrader valves are not very expensive though but you should have a pump & adapter on hand to repressurise the gun as its really easy to let too much air out untill you get the hang of it. I used a pcp stirrup pump, it only takes a few strokes so go easy if you use one.
 
As above, often when disturbing the schrader after a long time untouched, you can almost expect it to fail, as it also did on one of my 90's

I'd advise having the correct replacement valve to hand (early ones are a 2BA (I think) thread, along with the correct torque tool to remove and refit, as well as means of recharging the ram, before getting your tools out

A 3mm punch and a very light "toffee hammer" is all you need. Use swift, very light taps to relieve pressure. You don't need any more pressure to open the valve than you'd use to flick a crystal glass with your finger, to make it ring.
 
Rog1415 said:
So I've decided that i either need to reduce the power on my late model Fenman profile or sell it, after a 3 hour session down the range I looked like i'd just walked out of the gym. The guns sub 12 ft lbs and very accurate but i've got to the age where its just not that much fun to shoot anymore. It also feels like its under loads of stress.

Is it something that's easy to do and if so how?
Click to expand...
Can you say muzzle energy please? Noted 'sub 12' but not sure if that's spec. or performance.
Interested 'cos if cocking effort is high and energy low then sealing may be an issue.
 
It could be a worn seal hence more pressure needed if you have had to pump it up in your ownership or before you got it. @Brit Seals is doing seals for Theobens and may have one for your rifle unless its one of the Theoben experiments they often did . Some have said they have had to use less pressure in the ram with the Brit Seals seal.

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If Brit Seals don't have one to fit your Rifle ,Impact Airguns may have them. https://www.impactairguns.co.uk/about-us/airgun-repairs

My Evolution was hard to cock after a long session as it was the H.E system compared to the non H.E system in my Countryman Carbine. The countryman is a lot easier to cock even if i hold it where I would if cocking the Evolution.
 
Guns fine as had a service less than a year ago as the pressure/seals were gone. It shoots lovely, the cocking effort on the later guns like this however is ok for a short session but after 3 to 4 hours for me its too much. I've tried an earlier one and that seemed much easier for the same sort of power.
 
Rog1415 said:
Guns fine as had a service less than a year ago as the pressure/seals were gone. It shoots lovely, the cocking effort on the later guns like this however is ok for a short session but after 3 to 4 hours for me its too much. I've tried an earlier one and that seemed much easier for the same sort of power.
Click to expand...
What pressure has it been set to and what is the FPE ?
 
So finally got to play, checked the power and only doing 9.3-9.8ftlbs so i won't be reducing the pressure any. As i said it was supposed to have had a full service (cost enough!) at the begining of the year so will have to think on what to do next as still a bugger to cock. May strip and rebuild myself now the seals are available or just move it on will have to see.
 
Rog1415 said:
It also feels like its under loads of stress
Click to expand...

Having acquired a .22 HE Fennan quite recently, i can understand exactly what you are trying to say here, but IMO the "stress" that you are referring to, is totally down to the impeccable design & build quality around the barrel/breech, the massively strong detent, cross bolt, and "over engineered" lock up in general, they are in another league in this area, and bank vault lock up is 100% guaranteed every time.
Mine runs over the chrono with PCP like consistency at around 620 fps with 13.43 grain RS for a healthy 11.4 fpe, and i would imagine that a .177 model running at the same power could become a bit of a workout over a long plinking session 😱
It would be a real shame to get rid of such an iconic piece of British airgun history that you enjoy shooting, when dropping the power down to around 8fpe may solve any issues.
 
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We had our Fenman converted some time ago to a serviceable piston head crown seal (Aussie seal) after the original Theoben seal disintegrated and original replacements just weren’t available

Now the cocking action is effortless and silky smooth
once it was reassembled it took around a third less pressure in the ram to achieve a very consistent 11.5 ftlbs it also lost it’s snappy firing stroke Fenman’s and most rammers are renowned for worth considering if you’re able to find someone capable of carrying out this type of modification 🤘🏻

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