Beeman P1

Unbelievable,I just got off the phone, I just bought a P1. I was going to ask a similar question. You’re going to love your P1, I know because I have a P 17 as well. I think these models will soon be extinct with this name.

Odoyle thanks for sharing your library of information, can’t wait to watch those videos when I get time. While I am on it I’m going to thank you for telling everybody how accurate the 54 is, so I bought 54 pro lam. .22, and now looking for a 56th. Know where the stories going! It’s a fun ride. Crow 

wrote this post this afternoon didn’t push the button
 
Just pulled my .177 P1 out of storage. I'm wondering how to tell if the seal needs replacement. I when I bought it in the 80s I had originally heard the seals could "dry out" and because of that I assumed they were leather for some reason, but in watching strip down videos of the HW45 I see that the seal is plastic of some sort.

Is there a way to evaluate the function of the P1 and the seal without a chrono or dismantling the spring chamber? I haven't decided if I'm going to keep it or not and I'm a bit reluctant to take a pin punch and a hammer to it if I don't need to...

 
Seal is Teflon and as such, none drying. Use a touch of SM50 through your TP to waken it back up.

There is a cheap and cheerful way to test your .177 for power without a chrony. I have found typically 500 fps will send a pellet clean through both sides of a beans, or soup can (household tin can not a beer tinny) at usual pistol range of 10 yards. The P1 (Typ expected 550fps) will do the same at 18 to 20 yards...Its crude but should give you a ball park idea if its running as it should. For the record, a Tempest will do one side leaving the pellet inside and a P17 just about similar, sometimes not quite penetrating the one side at 10 yards.

The P1/45 benefits from a piston weight Top hat, which can be done DIY by fitting the mainspring guide rod the wrong way around, down inside the piston, but even better having a solid steel Top hat made up, with shorter guide rod at the usual end....so the mainspring is guided properly at both ends.. The TBT kit guides the mainspring at both ends, but spoils the power as the piston guide is in Delrin, which is way too light for the balance of this guns long TP...

I have tuned very many HW45 with the method i describe above for even greater performance and accuracy, discussed in the pistol threads with Johnny Piston on here..(worth a look) I did tell him that i was going to come up with an answer for the home meddler to perform such a tune without a lathe and have come up with a method if anyone is interested. (PM only)
 
I would defer to an expert tuner like Steveoo on this one, but I've read the piston seal on the P1 may work better if you occasionally dry-fire the gun ( ! ). Now before you head my way with torches and pitchforks, note that the Teflon (aka PTFE) piston seal is a very tough solid chunk without a "parachute" edge. The material can expand slightly and take a "set" under stress. (The Webley Hurricane / Tempest pistols have a very similar seal, and IIRC the instructions that originally came with these instructed you to dry fire it a couple times when setting up the gun, and from time to time thereafter.)

Now one wouldn't make a daily habit of dry-firing any springer of course! By "occasionally" I mean maybe one time, once a year, at the low power setting. And yes I have done this to my gun with apparent good effect.

It's been so long that I don't remember details, and I am definitely NOT an expert mechanic. But I successfully re-built my P1 with just a simple bar clamp as a spring compressor, and a piece of PVC pipe to help keep the spring from wandering off.

Last but not least, there was a gent named Todd Cooper who was the true Sensei for the P1, and had many good posts on using, testing, and servicing the gun. It would be worthwhile to google up a few of his old posts, and here's an archive synopsis to get you started.

http://www.eddiecolwell.tzo.com/HW45/HW45_-_Todd_Cooper.pdf


 
Fair comments from MD here....but if i can explain..

I really put the SM50 idea here for the novice, or non tuner... Teflon is not the best seal for the 45 as it can take a set and is a touch temp sensitive. You are better off with an Aussie red seal, but this not much use for a novice tuner. Regardless of seal type you should run the gun relatively dry due to the long TP restriction causing flash over heat if any lube in the gun....so whats the deal with the SM50..

My suggestion in reg a drop of SM50 is to restore a spent seal, in attempt to save the novice the expense of a rebuild and get the gun back to working with good power. It will diesel mildly for a dozen shots until the SM50 is burnt off, and without the need to dry fire (risking over expansion) it is enough to re-size the seal....then from there running the gun dry... I simply find it a less viscous method than dry firing, especially with the powerful spring of the 45...

The real improvement with a 45 is arresting that spring at its muzzle end, as it cants over and scrapes the side of the piston, reducing its life, and creating noise. Its ok, but if you want perfection, it needs arresting, with a small guide ...

Hobby pellets work great and can hit 600 fps if you know what you are doing....


 
A few notes on the Teflon (PTFE) seal.

Arriving in guns in the early 80s it was something of a new wonder material compared to the leather seals of the time. Lowest known coefficient of friction even to this day...non drying and machined up in 5 minutes....it seemed ideal and advocated by Beeman and Bowkett.

However, its not so great in the UK, with our vastly fluctuating temperature between a few degrees, 20 degrees and - degrees...because PTFE is temp sensitive. That bad that i often ran with 2 separate zeros. One for an average 15 degree day and one when freezing....It maybe worth noting at this point that you may not have this problem depending where you are State side, and where I cannot imagine anywhere would be as bad as here....Also, we are talking pistol here, where differences will be in the range 20 to 30 fps difference, not 60 fps as with the FWB sport rifle.

Notes for improvement...One thing that improves this issue, is polishing the seal face down until the barest of slip fit. This way any increase in diameter due to temp expansion, slows the gun much less than it might, while shrinkage, has the lesser impact....(this is noted by any seals in any guns which have worn to the point that they barely seal, but still make surprisingly good power but a tight seal can play real havoc with the guns power) ...nice slip fit then...

Notes on piston weighting. The OEM guide turned the wrong around to be inside the piston can give you 25 grams added weight to the piston, and send the Hobby pellet into 570 fps territory... Placed in at the opposite end (no weight in piston) loses 40 fps as the piston weight fights the long TP on its own.....its not the heaviest piston, being relieved for the duel cocking arm slots.....it needs the weight..

Finally, polish your barrels. HW in their wisdom put a lot of lube into the 45 and a used purchase can have loads added by uniformed shooters....It eventually gets up the barrel and plays havoc with accuracy. Use some proprietary firearm bore cleaner like Youngs 303, or a Napier bore cleaning kit and keep going until it comes up mirror finish..It pays big dividends..
 
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The piston showing the unusual double cocking slot grooves which adds strength to the cocking by using 2 cocking arms, but relieves the piston of a bit too much weight...and showing the guide rod which we can place down inside the piston to help with this weight reduction..

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Finally, a shorter but solid Top hat, giving us the same weight as the hollow OEM guide, but allowing room to fit the chopped down guide rod at the other end....We are now talking 20 yard rat buster...