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Wanting to change a few parts

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Re: Wanting to change a few parts

Postby alex2865 » Thu May 11, 2017 10:50 am

I'm using the jsbs heavies.mk1...i have a good barrel.its not pellet fussy.
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Re: Wanting to change a few parts

Postby alex2865 » Thu May 11, 2017 10:52 am

I was pushing the long as to fast.not acurite.so I tried the heavies.they seem to work better.alex
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Re: Wanting to change a few parts

Postby mann » Sat May 13, 2017 5:09 pm

Hi I took apart my 25 removed the hammer spring and adjuster was trying to figure out what moved because the power fell off both the hammer and the spring appeared to have stayed put so I don't know why power dropped polished where the hammer rides and decided to pull out the valve . Took it out opened the port to .154 or .153 also did the same to tp and opened up the front of it to the size of the new bigger lighter weight spring in the font of the vavle waiting on the new mds war hammer and 17 lb spring thinking trying the jsb heavies to see what I can push them to with a decent string and velocity what are
People's thoughts
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Re: Wanting to change a few parts

Postby ackuric » Sun May 14, 2017 7:03 pm

That port size should work great for ya if you're unregulated.
.25 M-rod

.04" Valve Stem / .212" Ports / Lane Reg / LW Valve Spring
Custom SSG's / 25gr Hammer / Peek Poppet @ .25" / 25cc Plenum Ext.

88 Shots 20.8 FPE
40 Shots 53.2 FPE
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Re: Wanting to change a few parts

Postby mann » Sun May 14, 2017 8:05 pm

My gun is unregulated also opened the barrel up to .153 and modded the bolt to about .116 . I'm hoping I will still get a decent amount of shots with a slight power gain don't know what to expect though for sure
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Re: Wanting to change a few parts

Postby ackuric » Mon May 15, 2017 6:45 am

IMHO with .153 ports, you are looking at an 'ideal' tune of around 50 fpe with jsb 34 gr. You should also be able to tune to do 60+ FPE for a few shots, but as psi drops below 2500 you will struggle to keep power above 60 FPE hence why I suggest a 50 FPE tune will be great, you could shoot from say 3K down to 2.1K, and with the right amount of work I don't see why you wouldn't get 24 shots or so at that power level. That would be my goal.

If you are willing to sacrafice Extreme Spread (vertical stringing) then you could even go crazy and shoot down to 1900 psi from 3k at around 40 FPE and should have a decent 3% or better bell curve / es
.25 M-rod

.04" Valve Stem / .212" Ports / Lane Reg / LW Valve Spring
Custom SSG's / 25gr Hammer / Peek Poppet @ .25" / 25cc Plenum Ext.

88 Shots 20.8 FPE
40 Shots 53.2 FPE
ackuric
 
Posts: 62
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Re: Wanting to change a few parts

Postby 22synrodn » Mon May 15, 2017 11:36 am

mann wrote:My gun is unregulated also opened the barrel up to .153 and modded the bolt to about .116 . I'm hoping I will still get a decent amount of shots with a slight power gain don't know what to expect though for sure


You can expect more power with a higher ES. By opening up the ports more you essentially created a sharper bell curve. The faster you push them, the lower the ES will be to a point. If the ES is too much for you, you can install regulator or a smaller TP ID to fix.
John 3:18

22 Synrod Unregulated. Tuned using JSB 18.13gr:
31 Shots @ 30.43 FPE, ES 1.60% (14 FPS)


25 Synrod Regulated. Tuned using JSB MKIIs 33.95gr:
32 Shots @ 51.57 FPE, ES 1.91% (16 FPS)
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Re: Wanting to change a few parts

Postby mann » Mon May 15, 2017 5:07 pm

I got my parts today installed the mds hammer and shortened the 17 lb spring filled the gun to 3000 psi and shot a pellet without any preload and the hammer floating into the valve got 641turned the hammer spring till it touched and added 2 turns to up the velocity took 16 shots and started at 754 ended at 800 and topped off the gun to see that the gun was at 2500 psi yet. turned the spring in all the way until it disengaged the threads filled to 2500 psi shot 16 more went from 811 to 825 back down to 814 at shot 16 which wasn't to bad of a string buwanted to get into the 900s removed the shorter spring install the full 17 lb spring backed off the spring adjuster to 0 again and ran a string with vms wide open ht 0 and hs 0 got decending string of 8 shots 868 down to 831 with 2500 fill .was going to try 3000 psi but tank was low and got 2700 psi fill ran 8 shots and got 870 to 847decending also dont know what to change to get to 900s if I should switch out to the stock heavier hammer or turn the spring up and try to balance it out with the hammer adjuster any thoughts would be great thanks
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Re: Wanting to change a few parts

Postby mann » Mon May 15, 2017 7:08 pm

The only tune I have ever done was the bstaley tune and was trying to tune that way but with out the o-rings and now a lighter mds hammer so I think I'm going about it the wrong way will have to some more reading in the tuning section I open to any ideas too thanks
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Re: Wanting to change a few parts

Postby ackuric » Fri May 19, 2017 7:33 am

mann wrote:The only tune I have ever done was the bstaley tune and was trying to tune that way but with out the o-rings and now a lighter mds hammer so I think I'm going about it the wrong way will have to some more reading in the tuning section I open to any ideas too thanks


Trying to get 900 FPS AND a Bell curve when unregulated is really not an easy task...certainly with .153 ports...what is happening is the port size is BARELY able to flow enough for your desired fps, so you're having to hit the valve stem so hard to create excessive lift + dwell which ultimately creates power shots / wastes air / has a huge cliff as a string...With the .153" porting, your IDEAL/EFFICIENT velocity would likely be around 840-860 FPS if you decide to stay at that port size.

I would do the following if I were you...

-open up the throat in the valve to .2188 (best done with a reamer, although I have done it with drill bits and dremel..)

-OR instead of the above, reduce poppet stem from .125" to .95"...you want to get as close to the poppet sealing surface as possible (without touching it, I used paper washers to protect it as they were very thin and allowed me to get really close) and only reduce the tiny bit of stem that is in the throat not the entire stem, this process is very simple imo and easier than drilling the throat when you're unequipped...as I have done both.

-open valve exit port, transfer port, barrel port to 11/64 / .1719" (I like to drill out in steps, from .153 > .160 > .1719...)

The above modifications will allow more air flow, will require less hammer strike too obtain the 900+ fps you're seeking, and should produce somewhat of a bell curve when tuned appropriately. Your bolt turned down to .116 is plenty to flow up to any port size up to .221" so you are plenty fine there. GL.

I would deeply consider a regulator if you're into modding this much, as there is no comparison and they are hands down much more enjoyable to tune than an unregulated rifle...at least imo..but going regulated means operating at even lower pressures and require generally even BIGGER ports than what I mentioned above for high power.
.25 M-rod

.04" Valve Stem / .212" Ports / Lane Reg / LW Valve Spring
Custom SSG's / 25gr Hammer / Peek Poppet @ .25" / 25cc Plenum Ext.

88 Shots 20.8 FPE
40 Shots 53.2 FPE
ackuric
 
Posts: 62
Joined: Mon Aug 22, 2016 11:43 pm

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