Build Started: Hammerli 850 Max Efficiency Tune @18-ish FPE?

[imadunatic]

Read through Bob's posts as well as many others on the Hammerli (yes I know it's fallen out of favor, but stumbled into a Refurb .22 for $180 shipped) and most of what I find is max FPE tunes. I don't use my airguns for hunting, but I do enjoy long range (NUAH) shooting every chance I get so the stock 12 FPE needs a boost, but I'd still like to be fairly easy on the bottle.

In bone stock form on this gun, 700 PSI air is slower than 700 psi  CO2, so I know this thing is not breathing well as is. I have collected all the information on porting, flow modding the valve and what not, and I'm not afraid to open things up, but I want to make sure I don't go too far.

So, Bob or anyone else listening, what would you recommend to get the most efficient tune at or near 16-20 FPE? I don't really need adjustability and I haven't bought the HPA bottle for it yet, the one caveat I'd like to maintain is being able to pull the bottle and install a 9 OZ CO2 for maximum summertime plinking fun, which means I really need to leave the pin in my Baker long adapter; if this is a major hang up in my quest, then I'll pull the pin, bore it out and install an extension on the regulator (tho I don't think I'll need that much volume for the power I'm looking to get).

Thanks in advance.
Kevin

[Tucobenedicto]

Common 850's tuning can reach about 32FPE with a 1900psi regulator and uses a 22ci bottle.A good tuning can give 60-70 shots.
If your goal is about 20 fpe,i think you can squeeze out 40-50 shots with a 13ci bottle around 1600psi.
A long adapter bored out without the rod is a great gain of regulated air and a big improvement in efficiency,but you can run bi fuel milling a flat on the adapter rod to allow better air flow.
If i am not wrong,Robert (rsterne) had a similar setup some years ago (without rod) and can give you more exact numbers.
Check for accuracy before touch the rifle,some bad .22 barrells around.
I am in the 850 resource too 

[imadunatic]

Common 850's tuning can reach about 32FPE with a 1900psi regulator and uses a 22ci bottle.A good tuning can give 60-70 shots.
If your goal is about 20 fpe,i think you can squeeze out 40-50 shots with a 13ci bottle around 1600psi.
A long adapter bored out without the rod is a great gain of regulated air and a big improvement in efficiency,but you can run bi fuel milling a flat on the adapter rod to allow better air flow.
If i am not wrong,Robert (rsterne) had a similar setup some years ago (without rod) and can give you more exact numbers.
Check for accuracy before touch the rifle,some bad .22 barrells around.
I am in the 850 resource too 

Accuracy is good at 15 meters, single hole groups out of JSB exact's and heavies (didn't like the monster's so much or the CPHP's though). It's almost dead of winter here, so I need a calm day for longer range testing; but it was very impressive at my indoor range.

Would it be more efficient to open up the valve and ports and run lower PSI or just leave it and crank the PSI? To be honest, I'd like to tune the gun for max efficiency on low pressure (under 1000 PSI) so that switching back and forth between HPA and CO2 is mostly painless. I was surprised when the HPA ran slower than the CO2 at the same pressure, but I have another rifle that does the same thing (the plastic M14 runs about 50% slower, it's just not designed for HPA flow).

I am in the 850 resource too 

I did notice you were a MOD over on the yellow, that is where I gathered all the info on flow modding the valve, barrel, etc. I will most likely still end up flow modding everything when I have it apart to smooth the barrel inlet (action is a little harsh right now, I'd like to smooth it out) and possibly add an extension just to increase my volume of regulated air, but I really don't want to hot rod this, I have other rifles for hunting, I don't need another! LOL

[Tucobenedicto]

Paintball regulators have a low flow rate compared with a 88grams CO2 bottle,this is the main reason you need around 1200psi on hpa to obtain the same performance.You can try a 1400psi setup without touching the valve and adapter and see the results.
Keep in mind you need a strongest hammer spring to run over 1100 psi,the 850 valve become very hard to open raising the work pressure.

[imadunatic]

Ok. Finally tore the 850 apart, lightened a few components to get the flow more in line with what HPA needs and gained almost 100 FPS at the same pressure.

Right up front, this is the last string I shot before I took it apart, regulator was set to 700 PSI, bone stock everything with Baker Long Adapter (also stock):

Description: Hammerli Tethered Hpa 700 psi
Notes 1: jsb exact heavy 18.13 gr
Bullet Weight (gr): 18.300
Temp: 7 (outside!!! Was 56 in the basement) °F
BP: 29.91 inHG
Shots

# FPS FT-LBS PF 8 566 13.02 10.36 7 566 13.02 10.36 6 565 12.97 10.34 5 551 12.34 10.08 4 553 12.43 10.12 3 563 12.88 10.30 2 562 12.84 10.28 1 570 13.20 10.43

Average: 562.00
StdDev: 6.63
Min: 551
Max: 570
Spread: 19

Was fairly anemic, and even slower than CO2.

Did lots of stuff, this is the result on the same air pressure:

Description: Hammerli 850 after flow mods. 700 psi JSB exact heavy 18 gr
Bullet Weight (gr): 18.130
Altitude (FT): 0.0
Temp: 34 °F
BP: 29.98 inHG
Shots

# FPS FT-LBS PF 8 ERROR 2 7 651 17.06 11.80 6 658 17.43 11.93 5 656 17.33 11.89 4 654 17.22 11.86 3 653 17.17 11.84 2 656 17.33 11.89 1 661 17.59 11.98

Average: 655.57
StdDev: 3.31
Min: 651
Max: 661
Spread: 10

Gained almost 100 FPS at the same pressure. Once I replace the coil spring in this regulator with a belleville stack and bump the pressure to 850-900, I should be right near the 18-20 FPE I want to be at with this set up. I'm still running the stock CO2 spring, so I'm guessing the air usage won't be much higher now than it was, I am trying to work out a way to incorporate a twin spring system like Travis has been playing with because there is no room for even one of my internal SSG's in this setup.

So, the list of mods is as follows:

Opened the throat (exhaust port on this design???) to .265"
Removed the screen and drilled 3 1/8" holes in the inlet side of the valve. Not sure why this doesn't respond well to a hogging like the QB or Crosman valves, but I'm guessing it has something to do with the design of the wide, flat poppet (Roald and others all recommended the 3 hole method, I am not one to argue).



Drilled a mini plenum into the adapter, .516" x 1.4" deep (I couldn't bring myself to bore it out as far as Bob did with his build years ago (2010 I think?) plus, this isn't a power build, it's a get the maximum power and efficiency out of 850-900 PSI build (I hope).



Opened the other end of the adapter to 21/64 and countersunk to help feed the 3 holes I machined into the valve:



Opened the bottom barrel port to 5/32 and touched up the leade on the back to try and smooth out the action. I kind of wish I would have knocked that corner off further, but I didn't want to go too far and risk a leak around the bolt:



I also wanted to maintain the option to run the airsource cylinders, as well as remove the HPA bottle and fit a 9oz CO2 bottle in the summer months when it's 80 degrees around here. In order to do that, and bore out the adapter, I needed another solution. That solution was an inline ASA that acts as a shutoff as well as a pin depressor for any attached tank. They work very smooth and this one popped up on ebay for $13 shipped:



Next step is to re-stack the regulator to bump the pressure about 150 lbs and retest. It may not even take that much to get where I want. If it ends up above 20 FPE at 900 PSI I'll back it off. This is strictly going to be a long range plinker (other than the occasional Starlings that show up in the spring).

I'll post back with what restacking brings when I get to it.

Many thanks to Tucobenedicto as well as Fivestar45 for the suggestions. I know that for many this gun is simply old news so they don't even bother reading the posts.... 

[anti-squirrel]

Ok. Finally tore the 850 apart, lightened a few components to get the flow more in line with what HPA needs and gained almost 100 FPS at the same pressure.

~[Did some awesome stuff]~

I know that for many this gun is simply old news so they don't even both reading the posts.... 

Hush.  This was a good "how-to", and if nothing a great refresher on tuning for a purpose.

[Horatio]

I know that for many this gun is simply old news so they don't even bother reading the posts.... 

Thanks for posting.
I've thought about getting one for a couple years, just haven't ponied up yet.

[Tucobenedicto]

It seems to me a perfect job Kevin,i doubt a twin spring system can be useful,but if you can fit it in the 850,i whant to see how 
With the standard  spring the 850 hammer is free flight,have you noticed hammer bounce on your setup?

[imadunatic]

It seems to me a perfect job Kevin,i doubt a twin spring system can be useful,but if you can fit it in the 850,i whant to see how 
With the standard  spring the 850 hammer is free flight,have you noticed hammer bounce on your setup?

I haven't noticed any hammer bounce, and some of the efficiency numbers others have posted at higher FPE leads me to believe it's a fairly efficient design to begin with. I'm glad you confirmed the negative preload on the hammer spring, I didn't have my valve complete when I reassembled the receiver the other night to confirm it, but it did seem to me that the spring was shorter than the stroke. It's easy to forget when you're working on this gun that it's a 10+ year old design. They really were ahead of their time, it's no wonder they were (are) so loved.

[imadunatic]

Thanks for posting.
I've thought about getting one for a couple years, just haven't ponied up yet.

If the build quality on the Gauntlet is anywhere near as nice as this 850, I think that is definitely going to be the way to go.... I wouldn't be surprised to see the 850 end production at some point, especially considering that the production costs on the 850 have to be driving the high normal price tag (so many little moving parts and pieces).

Oddly enough, I made my to do list on this rifle about a month ago, and then they announce the Gauntlet and it's almost a dead ringer for my plans on this rifle. Go figure. 

[imadunatic]

Hush.  This was a good "how-to", and if nothing a great refresher on tuning for a purpose.

Thanks Peter. Many of the builds you can find documented around the net are definitely aging and usually for max power; I figured it was time to document a different purpose build, might light a spark for someone else.

[Tucobenedicto]

I bought my 850 about eight years ago,this rifle was very popular for PCP conversions at that time.
Now there are many more options around,but is still an enjoyable rifle to shoot due to the accuracy of the barrells.
If Umarex will put on the Gauntlet a good barrell too at the price claimed we have a very interesting new option.

[imadunatic]

Well, as amazed as I was last night, I'm equally amazed tonight, but not in a good way. Restacked my reg so that it was putting out ~850 psi, hooked it up and lost about 10 FPS, which tells me the stock CO2 spring isn't strong enough to bump the valve even at 850 PSI (with the valve face opened up).

Created: 01-19-2017 07:57:53 PM
Description: Hammerli 850 after flow mods. 850 psi JSB EH
Bullet Weight (gr): 18.130
Shots

# FPS FT-LBS PF 7 636 16.29 11.53 6 645 16.75 11.69 5 649 16.96 11.77 4 639 16.44 11.59 3 641 16.54 11.62 2 634 16.18 11.49 1 653 17.17 11.84

Average: 642.43
StdDev: 6.92
Min: 634
Max: 653
Spread: 19
Shots/sec: 0.19


This leaves me at a bit of an impasse. I think the first thing I'm going to do is start shimming the spring to see how much it needs, and then I need to decide if I just want to leave well enough alone, buy another bottle and run it at 700 PSI. At 700 PSI, it's dangerously close to my target power (17.4ish foot pounds) and knowing that it's barely enough spring leads me to believe it's going to be fairly efficient at this pressure as well (thirdly, I fill from a standard SCUBA tank, so being able to shoot down to 650 PSI on the bottle is also nice).

I think I need to sleep on it for a day or 2 before I make any rash decisions. More than likely I'll be pulling it apart this weekend to shim the mainspring and see what I can do with the stock setup. I've set a goal for 18 FPE, and since I'm this close I'm likely going to see it through and decide what I want to do.

My wife and I are taking a class to get our concealed carry license this weekend, that will slow down my tinkering...

[Tucobenedicto]

You can shim the spring up to 1/4 without coil bind.
Another option is to shim hammer side with a little brass spacer like this.
http://i1379.photobucket.com/albums/ah127/Benedictoremirez/850/WP_20150206_002_zpso6b0d3tr.jpg
This add some weight to the hammer too,worked for me when i ran CO2.
The spring rate is about 10lb,but the 850 valve is hard to break open compared with common plastic poppett valves like crosman's.
Don't think the valve locks at your pressure,maybe you need simply a bit more dwell.

[imadunatic]

Thanks Tuco. I think for testing purposes I'm going to tether this so I can more closely monitor plenum/line pressures with my 2 1/2" gauge to make sure I'm not having another issue. It appears to me by nearly all accounts, this spring setup should be plenty up to 1000 PSI, so I'm wondering if I have another issue (like my inline ASA is causing issues...?)

In the meantime, I'm going to make a couple spacers like you mentioned, worst case I'll order a dominator spring and clip it to get where I want to be.

[Tucobenedicto]

The Dominator spring is very stiff and don't work well on the plastic guide,the dominator has a long metallic guide and a specific hammer drilled to accept the guide.
Thrust me,you don't need that spring,is designed to work about 1900psi.

[imadunatic]

You're right. That is exactly what I don't want. I do have some 14 lb spring stock in my stash, that might be pretty close (especially with negative preload) if the stock spring is 10 lbs. Just need some shop time now to work through it!! 

[Tucobenedicto]

You are so close to your target power i think the spacers are an option to try to keep low the cocking effort.

[imadunatic]

Rejoice! Rejoice! I had a few minutes after our class yesterday to play with this. I reshot a string tethered so I could monitor line pressure and sure enough it was slower on the 850 PSI than it was on 700 PSI, everything else being equal. So I pulled it apart, added .040" (1mm) of shim, reassembled and shot this string:

Created: 01-22-2017 04:23:22 PM
Description: Hammerli 850 850 psi JSB EH
Notes 1: .040" shim
Ballistic Coefficient: 1.000
Bullet Weight (gr): 18.130
Temp: 45 °F
BP: 29.62 inHG
Shots

# FPS FT-LBS PF 8 675 18.35 12.24 7 685 18.89 12.42 6 675 18.35 12.24 5 684 18.84 12.40 4 683 18.78 12.38 3 666 17.86 12.07 2 676 18.40 12.26 1 672 18.18 12.18

Average: 677.00
StdDev: 6.59
Min: 666
Max: 685
Spread: 19
Shots/sec: 0.16

That is pretty much spot on where I want to be with respect to power. I was able to get just over 14 clips (112 shots) from a 2000 psi fill before I had a substantial drop in POI. When the weather warms up this spring, I plan to do a full string through the Chrono so I can see exactly what it's doing and when it's doing it. But for now with our January thaw (it was almost 45 yesterday) I'm keeping it short.

[Tucobenedicto]

This mean a ton of shots at 3000psi fill.