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 Post subject: Brocock tuning
PostPosted: Sun Feb 23, 2014 11:36 pm 
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Joined: Sun Jul 28, 2013 8:34 pm
Posts: 1155
Location: Vernon BC
Hey guys, I just wanted to make post about my Brocock Concept super six .22 tuning so far. As I can't find anything like it.

My intention for tuning this gun is for power. If a disco at 2000 psi can put out 30 fpe (.22) with a respectable shot number for hunting, then maybe this gun can too? And my particular gun came underpowered.

After dissassembly, I quickly found out the barrel port was actually smaller than the other ports :? The transfer and valve port both measured roughly 3.5 mm while the barrel port was only 2 mm or 2.5 mm, I forgot :oops: . Before drilling out the barrel port, chrony testing revealed the gun averaged 677 fps with JSB Jumbo Heavy at 18.13 gr for an extreme spread of 13 fps in 18 shots.

After drilling the barrel port to 3.5 mm AND 2 turns CCW on the hammer screw, the gun might be breathing better? With H&N Barracuda Match 5.53 mm 21.14 gr, it averages 662.2 fps with an extreme spread of 18.8 fps for 24 shots! Thats a nice 2 ft lb boost plus nicer shot consistency. I did note though it seemed around the 13-14th shot it was peaking, from a 200 bar fill.

Also for a more comparative look at what the 3.5 mm barrel port and 2 turns did, the JSB's Heavies 18.13 gr average 706.9 fps with es of 19.8. But due to chrony issues while snowing (:roll:) , couldn't get a full string. Though during the 15 shots, it never fell below 700 fps and peaked at 719 fps.

A reason I'm happy with this very mild boost is, adjusting just the hammer spring had no effects, negative. Until I seeked help from someone! Thanks Bob for your very detailed and informative help! He gave me a nice low down on ways pcp can gain power.

I am going to continue the tuning. My goal is to try to squeeze a bit more power. My next steps are to look into opening up the ports a tad more. 4 mm. They are all 3.5 mm right now. One thing that is preventing me is I don't know how to get the valve out :?


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 Post subject: Re: Brocock tuning
PostPosted: Tue Mar 25, 2014 2:37 pm 
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Joined: Sun Jul 28, 2013 8:34 pm
Posts: 1155
Location: Vernon BC
Well I opened up all ports to 4mm. But unfortunately damaged my hammer spring at the 2 end coils :oops: . So I clipped the 2 coils and replaced with a nylon spacer approximately the same length of cut spring. And a wall thickness with enough clearance for the hammer to engage and cock.

The gun absolutely stock was shooting JSB Heavies 18.13gr at an average of 677 fps. Drilling ports to 3.5mm through and I adjusted the hammer bolt to 4.5mm which gave me 662 fps average (roughly 20-21 FPE) with 21.14gr Cuda's. A nice increase. And I only use 18 shots regardless of anything to save on pumping and I saw a small increase of Extreme Spread of about 3 fps for my 18 shots after finding that sweet spot.

After opening the ports to 4mm, I set the hammer bolt to a conservative 8.5mm to see how the tune went. I like the results and will play with different fills and shorter hammer bolt settings to try to get what I want. Higher FPE and 12-18 (2-3 clips) good shots. Btw also tried, at my own risk, cut a coil off the valve and replaced with a smaller length spacer, to lessen the tension. Don't ask what I was thinking. Can't turn back now.

190 BAR, 21.14gr Cuda's, 8.5mm hammer bolt, ports 4mm through, hammer/valve spring mods
719.3 fps
717.7
714.4
717.2
719.3
715.8 ~ 1 clip
719.4
711 (bad pellet, didn't fully debur barrel port)
721.9
733.3
731.8
731.5~ 2nd clip
ERROR- Double loaded pellet
ERROR- Double loaded pellet
721.9
724.5
721.2
720.9~ 3rd clip
722.5
726.1
717.7
725.3
717.8
718.9

So results look great to me. Peaking at 26 FPE with a conservative hammer setting. With the right fill pressure and fine tune the hammer bolt, I am hoping to achieve 12-18 shots all averaging above 25 FPE. Which I think is achievable. The hammer bolt tuning alone has increased the average fps by 40-50 fps higher before all mods. I hope it can do the same.

The affects of mods so far
Absolutely stock 3.5-2.5mm port- 640's average fps 21.14gr Cuda's Match 5.52mm for 18-19 FPE
Hammer bolt to 4.5mm protude and 3.5mm ports- 662 fps average fps 21.14gr Cuda's Match 5.52mm for 20-21 FPE
Hammer bolt to 8.5mm protude and 4.0mm ports- See above all shots above 714 fps and peaking at 733 fps for 26 FPE.

Congratulations if you made it this far. It's a pain to fully disassemble and reasemble. And I'm refinish the stock atm. I chose a black stain that I really layered on. And a satin water-based oil to coat it. After the stock is done and I adjusted the hammer for more power, I will report the final numbers.

Then I'm done tinkering with this gun! I've invested in a .25 AF Condor. So if I want/need the power, I'll use that :D


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 Post subject: Re: Brocock tuning
PostPosted: Fri Apr 11, 2014 12:33 pm 
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Joined: Sun Jul 28, 2013 8:34 pm
Posts: 1155
Location: Vernon BC
Success. I tuned the gun for more power and better efficiency and am happy with the results. I found numbers from the gun bone stock, out-the-box...

JSB Jumbo Heavy 18.13gr, 190 BAR, 18 shots, stock
High- 683.3 fps
Low- 670.3 fps
Average- 677.26 fps/ 18.46 FPE
Extreme Spread- 13 fps

Here are the numbers after hours of frustration and tinkering...

H&N Barracuda Match 5.53mm 21.14gr, 200 BAR, 24 shots, heavily modded
High- 731.2 fps
Low- 719.7 fps
Average- 724.72 fps/ 24.66 FPE
Extreme Spread- 11.5 fps


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 Post subject: Re: Brocock tuning
PostPosted: Fri Apr 11, 2014 5:55 pm 
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Joined: Tue Jan 29, 2013 6:54 pm
Posts: 2411
Location: Northeastern Ontario
That's quite an increase. Sounds like your effort has paid off.


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 Post subject: Re: Brocock tuning
PostPosted: Fri Apr 11, 2014 6:11 pm 
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Joined: Sun Jul 28, 2013 8:34 pm
Posts: 1155
Location: Vernon BC
Yes thanks! A lot of frustration and leaks were dealt with. Just got my Barska Ridgeline to put on it. Will do a review/comparison of it. Similar/clone specs to the Hawke Varmint line, but at 70ish percent the cost.


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