down the rabbit hole i go...hammerli 850 hpa conversion

[stevemag]

thanks, i can see how you can get sucked into this, i am enjoying it.

[stevemag]

I suggest to get some thin shims,say 0,2 or 0,25mm ,gaining 50-70psi don't require much shimming and you can stack multiple shims if needed.

ordered these,
316 Stainless Steel Round Shim, 0.025" Thick, 3/8" ID, packs of 10
316 Stainless Steel Round Shim, 0.02" Thick, 3/8" ID, packs of 10
watched a few videos on reg adjusting. . i'll keep ya posted

[stevemag]

some shim results
3x .025 shims =1400psi
1x .025 shim = 1000psi
1x .020 shim = 800psi
0 shims= 800psi
so it would seem that the first .02 does nothing? does this seem right?
in that case i will need to order .001 shims to get to 900psi?
seems wrong

[Tucobenedicto]

Can be the belleville stack was not preloaded in the starting configuration,so the .020 shim actually fill the gap without preloading the springs,why not testing the speed at 1000psi?
I don't think you can experience total valve lock at this pressure and you can do a simple test,check speed with a 1500-2000psi fill and record the numbers taking some shot below 1000psi.
If you notice a speed increase below 1000psi exceeding a 5% the hammer force is not enough for the pressure.

[stevemag]

Thank you, that makes sense. I started with the 3x025s  and worked down. I had assumed after 1x025 got me 1000psi that the 1x020 would put me at around 900psi that Roald said the hammer was tuned for.
I did this with a hand pump and double checked every thing to make sure I didn’t do something wrong.
Lots of pumping and dumping air. Took all day. Pump is making lots of grunting noises so I will take that apart today.
With a tank this would have been a pretty simple job.
I ordered some 001 and 002 shims. While I wait  for them I will test at 1000psi.
If you would like some shims send me your address, I have lots of them. 

[Tucobenedicto]

I hear you,testing a regulator hand pumping is a nightmare,making a few cc mini tank is a project i would to work in the future at the lathe.
Thank you for the offer,i have enough regulators parts around 

[stevemag]

That my friend, is a brilliant idea!

[Tucobenedicto]

Not mine,the idea is stolen from a few true experts here,great to avoid air and efforts wasting.

[stevemag]

went looking around the web, smallest tank i found was a 9ci.

[Tucobenedicto]

The small tanks i am talking about are made from steel rods,drilled,tapped and turned to obtain a proper o ring seat,not commercial ones.

[nervoustrigger]

Just an example, I made one with a piece of bar stock.  Managed it without the benefit of a lathe...
https://www.gatewaytoairguns.org/GTA/index.php?topic=73635

[Ribbonstone]

Certainly are hooked...which is what a hobby is supose to do. MAking tools (dead-head gauge is a help), modding the stock,  testing/adjusting/retesting.....it's all pretty much fun in retrospect (the bottle filling/dumping will take a while to fade into restrospective fun).

UNless you changed your first goal (70 shots at 700fps), think 1000fps output might do it...it'spartly a volume (plentium) issue, not just pressure.


Tried this on a QB, but getting to the threads was easier on those and by using a nearly full length tube, had a very large plentium.

Paintball type fill cap (made to plug into a paintball guns and use a remote line).

Something like this:



(been looking for the one I used some years back...haven't a clue where it got off to...so no personal picture).

Changed the simple nipple to a  PCP type fill nipple.

(Also useful to turn a big tube/big plentium back into a bulk fill co2 shooter).

Fill just the tube with air to a given pressure (hand pump) and take one shot. Refill whatever you used each shot.  NO freak-out here,were only testing co2-safe pressures.

As I was only looking for 12 foot pounds and was only looking to get the output in the ball park, figured it was easier to vary the little pump fill than to have to dump the tank/adjust the reg./ fill the tank (at least to a bit above regulation) for the pressure experiment.

Can't swear how well it would work with a small plentium or how well you could get it to the same pressure each test shot (or how accurate the pump's gauge), but figured out that I was probably good with about 850psi to get that 12 foot pounds.


Then I discovered gauged on/offs (which they may still make).  LIKIELY you'd not want the weight or to extend the tank out the distance of that brass on/off, but on the QB's it didn';t bother me (and they are still there).
DSCN1691 by Robert Dean, on Flickr
HAd one 1200psi tank.

By using the on off carefully, could just barely crack it open and watch the output pressure.

Turn the 1200psi tank off when the output side read right for your test.

Take one shot.

Get a pretty good idea of how much pressure that shot used (and if you know the volume, can rough estimate the actual amount of air used.)

Repeat the steps for the next shot (or vary the pressure to see what the best pressure would be for the way the rifle was tuned).


Just ideas....and trying to avoide too much testing that needed a tank-dump..reg. adjust...tank refill.  All I wanted was the feel (even one shot oat a time) of the bolt cycle (not real happy with stiff cocking bolts) and an idea of about what to expect for energy.

(Although, not being in a hurry, would usually shoot the rifle down rather than just dump the tank. I'd already "paid" (with effort) for the air, so may as well get some use out of it rather than just venting it.)

[stevemag]

very clever!

[Ribbonstone]

The gift of slackerism.

Figured I worked pumping that darn tank up, be darn if I would just vent it to work on the regulator rather than shoot it. May be the "wrong"speed,but prtetty much shot as wellno matter how air-wasteful/wrong speed it turned out to be.

So figured out a way to get the goal energy pressure with the least work...slackerism may not be such a bad thing.

Thinking about it...really can't remeber if that remote fill can was the tapered "English" thread of the stright American" thread....or if I just man handled it and jammed the wrong one into that cap (with sealant).  Eventually I'll find it (in some odd unexpected location) and find out.


The brass on/off did not look right sticking out of the 850,but I did use it for testing. I just removed it after the test. (for that matter,never bothered to put the scope back on or the stock back on during testing...doesn't make any difference if all you are looking for is a vel./energy level).

[stevemag]

Well I didnt expect this at all...
13ci tank regulated to 850
280 pumps to fill from 0 to2900psi
# of shots    140  !!!   WHAT?!  yup from 2900 down to 900ish
high 650fps
low 593fps
average 616fpe
13.5 foot pounds
I was hoping for 70 shots at 700fps.

for some reason today the .025 shim read at 950 psi so i just tested,
 tank filled to 1600
25 shots  with same 15.89 pellets
hi    691fps
low 646fps
av   669fps
fpe= 15.8
thats about a 10% increase, i assume 10% fewer shots per fill.
should put me around 125 shots.
i think i can tweek a little more.
still a pretty extreme spread, i don't know what i should have expected.
since i can screw the bottles on and off while filled, i think i 'll get a second bottle.
 

[Tucobenedicto]

Sometimes regulators needs some "cycles" to set,some short bleed during testing helps.
My 850 and my Prod,with the same regulators have a spread of about 10-15fps.They are china clones rebuilded using ninja pistons and industrial grade bellevilles,i polished the sharp edges of the springs and lubed the orings and the springs with silicone grease.
A proper hammer lubing can play a role in consistency too.

[Ribbonstone]

  Not as safe an assuption as you might expect...logical, but it often doesn't work out quite that neatly.Not a big jump in pressure/power, but could be using a different amount of air.NOrmally a little more,but it'spossible with the increased pressure you'd use a bit less.

Good news on HPA's is that you could just fill it to 1500psi, shoot it down to 1000psi, and be pretty sure (the gauges aren't the best/easiest to read...which is why I picked the "big lines") of the number of shots for 500psi of air use.If you ran that tank from 3000 to 1000 before a refill, would be pretty sure of 4X the shots of the 500psi test.

[stevemag]

time will tell, didn't have time to pump her all the way then shoot down today...but i like the direction i'm going in.

[Ribbonstone]

Isn't uniform pressure from a HPA tank what HPA is all about?


If you get 22 shots (or whatever you find) from 500psi (over reg. pressure 1000-1500) that shouldn't you get 4Xas many shots if filled to 3K?


Know that's an odd way of looking at it....but it's what regulation actually does.....provide the same amount of gas pressure, so  the same performance for whatever tune you settle on.Could be a real efficient tune...or a real gas-hog tune...but it will be the same until you shoot down to reg. output.

[stevemag]

Isn't uniform pressure from a HPA tank what HPA is all about?


If you get 22 shots (or whatever you find) from 500psi (over reg. pressure 1000-1500) that shouldn't you get 4Xas many shots if filled to 3K?


Know that's an odd way of looking at it....but it's what regulation actually does.....provide the same amount of gas pressure, so  the same performance for whatever tune you settle on.Could be a real efficient tune...or a real gas-hog tune...but it will be the same until you shoot down to reg. output.

i am pretty sure i agree with you, and you know 100 times more about this process then me. the 25 shots i did today(to noisy to do more) the gauge on the bottle went from about 1600 to about 1400. not sure if that sheds any more light.