Author Topic: down the rabbit hole i go...hammerli 850 hpa conversion (Read 8261 times))

stevemag · « **Reply #60 on:** February 16, 2019, 04:57:08 PM »

Quote from: Ribbonstone on February 16, 2019, 01:27:19 PM

Give the whole back-story,.,,,right about now would consider it "done" for what you use it for.

If you really have to have 700fps from 16gr, you might ask yourself "why?". Same question about 140 shots...why more?

For the first...run though some ballistic programs over the max range actually used (lets say 100 feet/33 yards for back yard playing/pesting). Given that the sight line and bore line are already out sysc. by the scope height, are always going to be in a rise/peak/fall situation. If you balance the max. rise of each velocity (614 vs 700fps) over that short range (so that the max rise at the peak and the fall at the 33 yard mark are the same distance)...pretty much come up with "ratsarse" of real difference in inches of rise and fall.

(right about here I give myseklf a lecture. "Come on Mr.Dumas (misspornouced to dumbass), if you are shooting at the home range, where you know the yardage to the foot, what is the real difference in a fraction of an inch rise and fall when the range is known?)

For the second...other than the rabbit hole effect...if you aren't shooting more than 140 shots per sitting, then it doesn't make any difference to the shooting session....can always refill in the "off hours".

right now the gun is about 50-75 fps shy of where roald tuned it on co2, this is my most accurate air rifle. and i would like to venture into the world of field target. pretty sure i need 60 shots for that. thats why 70 was my goal. besides...everybody likes a little more power.

stevemag · « **Reply #61 on:** February 16, 2019, 05:00:18 PM »

Quote from: Tucobenedicto on February 16, 2019, 12:48:22 PM

A 50psi raise in regulator pressure is a small amount,can be achieved by shimming the spring pack in the reg with very thin shims,probably 0,15-0,25mm but every regulator is different from another.I suggest to start with very thin shims (even 0,1mm) and test speed,unless you want to build a regulator tester.
If you open the regulator,be careful to not fall the belleville springs and take note of the actual arrangement of the springs refferred to each other.
An 850psi regulator can use a classic spiral spring instead of bellevilles,but the concept remain the same.

i was just looking up how to make a regulator tester. seems simple nuff. also found some videos on adjusting regs. the biggest pain will be pumping and dumping air. maybe i will get lucky and nail it on the first try. reg tester first though.

Nvreloader · « **Reply #62 on:** February 16, 2019, 07:46:02 PM »

Steve

If you don't know, you use the reg tester, to find the set point pressure, etc.

When you build it, keep the internal hole/depth as small as possible volume wise,
you are only testing the output of the reg, less pumping.

Tia,
Don

Ribbonstone · « **Reply #63 on:** February 16, 2019, 07:52:06 PM »

Did try to get 850 HPA and tanker co2 to work out to to some compromise setting that would allow me to use both depending on the temperturewith just a change in strier spring tension (a little restgrictive for one/ a little gas hogish for the other...somthing that kind of met in the middle).

Worked the hardest on a Crosman 2250 conversion...and got close enough that it (in the words of my Uncle Harry) "make no never mind".

WOW..thinging back, that was one deep rabbit hole...took a whole lot of pharting around getting it to kind of meet in the middle

Wuld use HPA air (with the hammer spring backed out a little) during the short cold winter here (actually, about 3-4 months down here) and small paintball tanks of co2 in the warm months (with the striker spring screwed in a little).

Really wasn't great at gas use for either, but it was a useful critter.

But unlike you, was not trying for 16gr. at 700 fps...more like a two-gas-ballance with 13.6gr. at 580 in the little carbine to get the the short little SOB "dual gas".

(NOPE...wouldn't even try that again...either co2 or air, not going to try for a true dual gas/dual use/same speed rifle again.Make it one or the other, and lit it live to it's true potential.)

stevemag · « **Reply #64 on:** February 16, 2019, 07:53:28 PM »

i figured i only need to pump to 1000psi right?

stevemag · « **Reply #65 on:** February 16, 2019, 07:57:59 PM »

Quote from: Ribbonstone on February 16, 2019, 07:52:06 PM

Did try to get 850 HPA and tanker co2 to work out to to some compromise setting that would allow me to use both depending on the temperturewith just a change in strier spring tension (a little restgrictive for one/ a little gas hogish for the other...somthing that kind of met in the middle).

Worked the hardest on a Crosman 2250 conversion...and got close enough that it (in the words of my Uncle Harry) "make no never mind".

WOW..thinging back, that was one deep rabbit hole...took a whole lot of pharting around getting it to kind of meet in the middle

Wuld use HPA air (with the hammer spring backed out a little) during the short cold winter here (actually, about 3-4 months down here) and small paintball tanks of co2 in the warm months (with the striker spring screwed in a little).

Really wasn't great at gas use for either, but it was a useful critter.

But unlike you, was not trying for 16gr. at 700 fps...more like a two-gas-ballance with 13.6gr. at 580 in the little carbine to get the the short little SOB "dual gas".

(NOPE...wouldn't even try that again...either co2 or air, not going to try for a true dual gas/dual use/same speed rifle again.Make it one or the other, and lit it live to it's true potential.)

thats a fine looking airgun.
i'm just gonna tinker a little bit more, if it proves to be more trouble than its worth i'll be ok with what i have, but..just little more tinkering...

Ribbonstone · « **Reply #66 on:** February 16, 2019, 08:11:14 PM »

With thr 850 regged HPA tanks, I did try to sneak up on a full fill.

BUT you know it doesn't make a differnece...it's all prtty much effort in vs. energy out.

IF you start at 800psi (where the reg fell off regulation) and put in 1000psi, you get the tank up ato 1800psi. Lets say you shoot a quick session of 18-25 shots. That leaves you at about 1000psi. Put in another 1000 PSI during a pump session, have another quick shooting session, and the tank is left at something like 1200 PSi.

You keep gaining pressure after each shooting session utnil you finally get to 2900-3000 fill pressure.

Which from there, got me the same number of short shooting sessions in declining pressure.

So over all, it was the same effort in vs. shots out...but as a hand pump filler, always felt the decling pressuier shots were "pre-paid".

stevemag · « **Reply #67 on:** February 18, 2019, 07:42:00 PM »

still waiting for parts, meanwhile heres a few pics

stevemag · « **Reply #68 on:** February 18, 2019, 07:46:40 PM »

i also made a cover for it out of kydex, snaps on pretty solid. not terrible. figured while i was at it i'd make a cheek riser. attached with velcro. seems to work ok.

Nvreloader · « **Reply #69 on:** February 18, 2019, 08:38:02 PM »

Steve

I am very interested in your cheek riser, as I need 3 of them for my 850's.

How hard is the Kydex to work with, never used it before, any info pointers to pass along?

Thanks,
Don

stevemag · « **Reply #70 on:** February 18, 2019, 09:05:14 PM »

Quote from: Nvreloader on February 18, 2019, 08:38:02 PM

Steve

I am very interested in your cheek riser, as I need 3 of them for my 850's.

How hard is the Kydex to work with, never used it before, any info pointers to pass along?

Thanks,
Don

really easy , even for me.
got the kydex on eBay. wrapped a piece of paper over the stock and traced it. cut it out. traced on kydex. cut the kydex with heavy duty scissors. sanded edges smooth . if i had a ban saw i could have lots more fun with it.
heat it in the oven on a cookie sheet @ 350 for about 5-10 minutes. i used some parchment paper but i don't think you need to.
it cools pretty quick so you gotta move pretty fast. wrapped around the stock and secured it with an elastic elbow brace really tight. 10 minutes later all done.
the best part is if you screw up you can re heat it and do it again.
i attached mine with velcro but I'm sure there are better ways.

Tucobenedicto · « **Reply #71 on:** February 19, 2019, 01:45:36 AM »

Quote from: stevemag on February 18, 2019, 07:46:40 PM

i also made a cover for it out of kydex, snaps on pretty solid. not terrible. figured while i was at it i'd make a cheek riser. attached with velcro. seems to work ok.

Very creative

Nvreloader · « **Reply #72 on:** February 19, 2019, 01:22:49 PM »

Thanks Steve

I'll try that on the 79 first, because of the high mounting of the scope,
I have a very hard time getting a good stock weld, and I am know that it affects the accuracy etc.

Tia,
Don

stevemag · « **Reply #73 on:** February 19, 2019, 02:30:58 PM »

i put this on my qb78 years ago.

stevemag · « **Reply #74 on:** February 19, 2019, 10:54:41 PM »

Don, here is a very cheap and very comfortable version i did a few years back. i did the kydex one just because i had the material. i may switch back to the elbow brace

Ribbonstone · « **Reply #75 on:** February 19, 2019, 11:41:11 PM »

Kept in a peak summer temp car trunk(or a house'sattic) don't; know for sure what co2 pressuremight reach as it usually blows the burst disk at somewhere between 12800 and 2000psi.

Kept in the refridgerator(and not even the freezer),same tank will likely go about 500-525 psi.

So to take advanage of hot weather co2 temps,would have to crank a co2's striker tesnion way up to match,woich wouldmake even 85F tempertures a noticably drop in velocity.

OR

You could set up a co2 rifle to run real well at 65F,but it'sgoing to get slower and slower as the temp.rises to 90F(or even valve lock).

Not to get me wrong here...I actually like co2....but from under 55Fand over 95F, I leave it in the house and shoot somthing else.

stevemag · « **Reply #76 on:** February 20, 2019, 04:15:53 PM »

made a output test, seems Roald was right on the money when he said it seemed more like 820psi , he knows his stuff.

Tucobenedicto · « **Reply #77 on:** February 20, 2019, 04:23:18 PM »

Quote from: stevemag on February 20, 2019, 04:15:53 PM

made a output test, seems Roald was right on the money when he said it seemed more like 820psi , he knows his stuff.

No doubt about this,he tuned and converted many of this rifles in all calibers.

stevemag · « **Reply #78 on:** February 20, 2019, 04:27:35 PM »

i will order some shims and see if it makes a difference.

Tucobenedicto · « **Reply #79 on:** February 20, 2019, 04:37:43 PM »

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.

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

Author Topic: down the rabbit hole i go...hammerli 850 hpa conversion (Read 8261 times))