Tuning Hw45 tuning results

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vmaxpro

vmaxpro

Member
Sep 11, 2019
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Virginia, United States
Pretty happy with these results overall. Heres what i did, its not much

honed the compression tube to roundness of .0002

polished piston

made new teflon piston head and hand fit to bore

ground flat and polished spring ends

made 2 spring guides from tool steel and polished

better chamfer on barrel so pellets seat flush

Combat grips

ok so this is with little to no detonation over 10 shots

6.79 gr GTO 625fps es4

7.0gr rws hobby 555fps es 8

8.3gr rws dome 525fps es 2

I dont understand why the gto is so much faster. Now these are not ground breaking speeds but this is running dry. Accuracy has been great!


 
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Its because you have sensibly chosen steel guides....even better....tool steel. Plus guiding at both ends to keep the mainspring straight.

To hit 600 fps in the P1/45 you require weight in the piston as the main requirement....but not exceeding 30 grams. At which, velocity starts dropping and the clunk becomes more difficult. I usually worked on 20 grams. The forward guide at the muzzle end can be Delrin if you do not like the weight and and want a bit lower friction that end, but you must have steel in the piston, or drop to 500 fps....well done.
 
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 Cheers buddy...Yeah I am trying to put it out there to not waste money on the TBT kit for this. Putting a piddling bit of plastic down in the piston of one of these loses a good ftlb, or more and even brings in a bit of secondary piston bounce. Its dumbing down spring twang sure enough, but wrecking the potential of the gun.

Trouble is, anyone gives his kits a bit of bad press and you are banned off the forums he supports....and thus only the positive feedback remains...

The positive feedback for the TBT kit is coming from the fact that the guide at the muzzle end of the gun, is indeed killing twang, but you can kill the twang and still have the weight in the piston. The kit was made down to a price therefore, with both ends being made in plastic. 

This gun needs weight in the piston (Bowkett and Pope) and the distal end of the spring arresting with a small guide, which could be Delrin if wanted, at least if you want to make 550 fps plus. You have just proved it!


 
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Well yep you are correct I get zero twang! Whats great is I maintained factory velocity, with no detonation. Not even a little smoke in the bore. Velocity is nice and tight now. Its a pretty impressive little gun. Offhand I have no problems hitting the small end of soda cans out to 45 yards. Dropped a few birds, and some rats. Thanks for tip again!
 
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Steveoo said:
Its because you have sensibly chosen steel guides....even better....tool steel. Plus guiding at both ends to keep the mainspring straight.

To hit 600 fps in the P1/45 you require weight in the piston as the main requirement....but not exceeding 30 grams. At which, velocity starts dropping and the clunk becomes more difficult. I usually worked on 20 grams. The forward guide at the muzzle end can be Delrin if you do not like the weight and and want a bit lower friction that end, but you must have steel in the piston, or drop to 500 fps....well done.
Click to expand...
Thanks for sharing your knowledge. But do you mean 30g total weight of piston/TopHat or just for the TopHat?
 
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Just the top hat but do not exceed much above 20 grams as i mentioned power starts going in the wrong direction at much above 20 grams…
My own experiments seemed to hit a wall at approx 17 grams (with decent 8.4 grain pellets) with no gain at up to 20 grams and then starting to drop off as weight approached 25 grams.
Without weight however (a plastic top hat) you lose a good 40 fps
 
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Always go OEM spring when anything HW….they make lasting quality springs that have stood the test of time….most of the top tuners running with their springs.

The key with the 45 is guiding at the opposite end to the piston with some sort of guide, or the spring wants to cant over, causing wall friction and a bent spring in quite a short time. Anything to arrest the spring at that end is fine…(A short top hat at the opposite end that you would normally add in a rifle)
Then forget the Tinbum kit or Eagle kit as it will turn the gun into a benign 4.5ftlbs …..damping it sure, but destroying the reason for the design or the gun in the first place…Why do that when you can get a Tempest instead, it will not need tuning for a soft 4ftlbs.
Finally get a good 15 -20 grams of weight down inside the piston…to get the pellets up above 550fps..
JSB domes…
 
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Yep, all previous springs have been bent! Had this gun since 1989. Although I can't really agree with the "getting a Tempest" part. It's a fine plinker but very hard to shoot. Without adding an over travel screw it's kinda hopeless in fact! I think I'd rather have a demasculated HW45 if accuracy would be a priority. I love my Tempest, and have had 3 or 4 in the past. The one I kept was bought used at Scotty's gunshop in downtown Denver in the early 1990s. He was quite a character, no idea if that shop is still around?
 
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I would not suggest getting a Tempest if the 45 is performing properly, because i have proved time and time again that the 45 outguns it. At the approach to 570 fps, the pellets are getting out of the gun before the comical recoil starts…Thus its velocity that counts far more than damped feel.
However, if tuned down to 4ftlbs territory with the use of damping kits any such advantage is lost….I then do not see much point of having it over a Tempest…a more compact gun which feels nicer in the hand than a 45 and much more easily serviced. We would buy the bigger, bulkier gun for its power, potential for longer range shooting, possible short range pests etc..
If its purely accuracy and nice soft cycle you wanting ….you could go a 75.
 
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I have had all these guns. The P2 was a disappointment of sorts. Very well built Weihrauch quality of course. But the hammer jars the sight picture when it smacks the valve. I have a Tau-7 that does everything I did with it better, except accepting optics, which the trap door action on the Tau-7 pretty much precludes entirely. The Tempest is a well proven pesting gun all over the world, and it would be hard to argue against all the dead rats and sparrows these guns have killed over the last century! Here's a picture of my .22 Tempest, with added over travel screw, which helps a lot! The holster was a Beeman special made by Biachi:
IMG_0486.jpeg
 
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Thats a nice Tempest and like the over travel screw. I think its great when guys engineer in an improvement …or at least try to.
One thing you can try is meddling with the TP screw at the top of the rear sight block…
You can make the screw slightly longer and add a ball nose end to it by filing it round when spun in a battery drill
The idea is to minimise the lost volume in the TP and by being round the air flows around it more efficiently..
I have tried sleeving the entire port but is a bit of a challenge for the novice..
 
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Steveoo said:
Thats a nice Tempest and like the over travel screw. Also looks like you have removed the safety and added a steel Trigger blade?..I think its great when guys engineer in an improvement …or at least try to.
One thing you can try is meddling with the TP screw at the top of the rear sight block…
You can make the screw slightly longer and add a ball nose end to it by filing it round when spun in a battery drill
The idea is to minimise the lost volume in the TP and by being round the air flows around it more efficiently..
I have tried sleeving the entire port but is a bit of a challenge for the novice….Done correctly you can pick up 15 fps with most pellet types…
Click to expand...
 
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I finished making a new spring guide today. I went with brass since I forgot to order bronze. I made it the same weigh as the original (29g), and it ended up a little shorter thant the POS steel they put in at the factory (it was only tight on half its length!). I also made a spring guide for the other end. It is fixed in place with the cross pin for the compression tube end. There is a hole though the compression tube end, I used that. I removed all the burrs in the cocking slots, using various needle files and bent rifflers, to avoid messing up the sharp corner on the Aussie seal I put in. O'boy did that make the gun nicer to cock! I did some polishing on various portions, making shure there are nothing to drag or bind. Put Maccari tar on the guides, and some regular moly on the spring and piston. I have not had time to chrony, since day light is short now. But it feels faster. First shot was on an empty breach, giving a sharp crack. Somehow the pellet must have fallen out when loading. I then tried it on an old tin can, a little bigger than a soda can, 25m out. Hit it on the first try, felt great! After dinner I sat town on my weight bench, that I use solely for testing airguns! ;) I gives a perfect rest for my arms. Good investment! And shot this group, using shoting glasses with an adjustable iris (I'm over 50), and regular open sights:
IMG_0488.jpeg
 
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