Best mounting method for aftermarket barrel for PP700?
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Best mounting method for aftermarket barrel for PP700?
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Topic: Best mounting method for aftermarket barrel for PP700? (Read 6082 times))
darkcharisma
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Real Name: duy
Re: Best mounting method for aftermarket barrel for PP700?
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Reply #60 on:
May 12, 2021, 05:36:55 PM »
cool place to mount one. i got one mounted on the side. m8x1 gauge.
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freddich
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Re: Best mounting method for aftermarket barrel for PP700?
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Reply #61 on:
May 13, 2021, 02:45:13 AM »
Hmm that's interesting.. May I ask why the 3 gauges? Does it have two regulators?
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darkcharisma
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Real Name: duy
Re: Best mounting method for aftermarket barrel for PP700?
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Reply #62 on:
May 13, 2021, 06:25:25 PM »
one gauge from the bottle, another gauge in the drop block and one on the receiver on the other side. this left side has a plenum. The Oem regulator has creep i threw it away. running off bottle reg.
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freddich
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Re: Best mounting method for aftermarket barrel for PP700?
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Reply #63 on:
May 15, 2021, 09:43:23 AM »
Ah right I think I saw your added plenum in another pp700 thread a while back? What kind of performance gains did you get from adding it along with the longer barrel? I'm thinking of adding one myself as I feel it might be needed for 25 cal on this gun, as well as expanding the hole in the valve that leads to the breech block.
Impressive work!
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darkcharisma
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Real Name: duy
Re: Best mounting method for aftermarket barrel for PP700?
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Reply #64 on:
May 15, 2021, 02:00:09 PM »
The 25 cal 600mm fx slug liner does 770fps with 34 NSA at 1800psi. it does 835fps with 34jsb pellets at 2100psi. i detuned it to 750fps with 34nsa.
i am thinking of putting a 22 back and shoot 15nsa slugs at 1000fps. the 25 cal is a 50 yard gun. it has a big rainbow flight.
I made a bigger valve and bigger swing gate, it helps with power along with the plenum.
-----
When i have time. i will replace the receiver with a bigger plenum built i to it and a balaced valve so i dont have to crank the hammer all the way up.
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Last Edit: May 15, 2021, 02:10:15 PM by darkcharisma
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freddich
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Re: Best mounting method for aftermarket barrel for PP700?
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Reply #65 on:
June 04, 2021, 06:16:21 PM »
Here are some results with the regulator installed. In order to test performance on a lot of different pressures, I simply adjusted the reg to max pressure and shot the gun until empty. Thus, the results you're seeing are "unregulated", but with the reg installed because I need to test it with the proper plenum volume.
It seems to work best at around 120-140bar, and then pretty heavily drops off towards 150bar. I'd like to tune it to work somewhat efficiently at the maximum regulated pressure the reg will handle, between 150 and 160bar, so I'll be putting in a heavier hammer spring first and see what happens.
For those wondering, the highest velocity of 244m/s equates to about 35 joules, or 25Ft/Lbs, and that's with an unmodified valve and not much plenum at all.
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freddich
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Re: Best mounting method for aftermarket barrel for PP700?
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Reply #66 on:
June 06, 2021, 04:55:52 PM »
Tried tightening the hammer spring as tight as it'll get and it actually made a slight difference, increasing the velocity by about 7-10 m/s or so. Only problem with that is I feel like A LOT of efficiency was lost, judging by the noise it makes. Seems like the fact that the spring is still compressed when the valve is open is making it stay open until the pellet has left the barrel which (I think) is why it got so loud.
Does anyone know what difference it would make is I were to remove the "valve return spring" (and perhaps more importantly the restrictive nut it rests on) now that I have a quality regulator in the gun?
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nervoustrigger
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Real Name: Jason
Re: Best mounting method for aftermarket barrel for PP700?
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Reply #67 on:
June 06, 2021, 05:52:32 PM »
The valve spring isn't strictly required for basic operation but it plays a role in the self-regulation characteristics of the valve. Keeping it is beneficial to holding a tight extreme spread. To what extent? Well, it depends on how closely the regulator approaches being a perfect regulator...always producing exactly the same output pressure.
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MS
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freddich
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Posts: 75
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Re: Best mounting method for aftermarket barrel for PP700?
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Reply #68 on:
June 06, 2021, 06:14:46 PM »
Guess I'll have to try it... As I don't have a super accurate gauge to measure the plenum pressure with I can's tell how close to perfect the reg is, but it's at least within 5 bar for the whole pressure range. While I have it apart I'll expand the transfer port through the breech block to 5.5mm and the valve as big as possible without leaking as well.
After that, the only modifications I have left to make will be a bigger plenum and a weight adjustable hammer.
For this project, power+accuracy>shot count. I don't really need shot count beyond say 3-5 shots for my purposes, though 10-15 would be nice.
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darkcharisma
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Real Name: duy
Re: Best mounting method for aftermarket barrel for PP700?
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Reply #69 on:
June 06, 2021, 08:35:57 PM »
Oh man, I have been spoiled by that bottle reg and the shot count is +30 at + 40fpe in 25 cal. Currently my dual hammer springs almost maxed out, it performs well at 1600 psi as it gave the most FPE, but it occasionally dumps air so I run the reg at 1800psi. And I don't have the nut that secures the valve spring, my valve spring is resting against the back of the offset 9mm plenum hole. really consistent from shot to shot although my valve ID is a bit bigger compared to the poem valve, so we can't really compare that.
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freddich
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Re: Best mounting method for aftermarket barrel for PP700?
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Reply #70 on:
June 07, 2021, 06:22:59 AM »
I was actually really happy with the performance and shot count I got when I tested it Yesterday. With a reg pressure of 120bar (1750psi) I got around 30 shots on a fill at ~240 m/s (787fps). Quite efficient for having not tuned it at all (and such a small tank) IMO!
I'm hoping to improve performance by 30% for a loss in shot count of 50%, giving me 15 shots at say 35 ft/lbs.
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freddich
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Posts: 75
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Re: Best mounting method for aftermarket barrel for PP700?
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Reply #71 on:
June 07, 2021, 05:16:43 PM »
Update again: As I don't have a heavier spring at the moment and wanted to test performance at 150bar somewhat properly, I just removed the little silver trigger piece that keeps the hammer from travelling further back than it's supposed to, and pulled it back until it had a travel of almost 90 degrees (almost double what you're supposed to have) and let go manually. Results are very promising; the velocity jumped from 787 to 917fps, giving me 34ft/lbs, and it sounded a lot less wasteful to me as well. It probably consumes more air than before given the high pressure, but it seems like the valve also closed faster.
Overall I'm happier and happier the more I fiddle with it.. I was aiming at high 20s ft/lbs with the new barrel but it looks like I'll probably get to 40.
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freddich
Shooter
Posts: 75
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Re: Best mounting method for aftermarket barrel for PP700?
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Reply #72 on:
June 09, 2021, 03:09:37 PM »
I modified the valve and breech block quite a bit by first expanding the transfer port to 6mm (Eventually I will get a 25cal barrel for t, thus the bigger-than-bore tansfer port) all the way through the block. I then took out the valve and milled a slightly elongated 4.5mm hole equal in cross sectional area to the 6mm hole it lines up with for optimal flow. I also plugged all the holes that I don't need with epoxy, leaving only the bigger hole I made which lines up perfectly with the transfer port.
What you see in the photo is the valve stem from all the way above the gun. Obviously the hole in the top will be plugged with a small piece rod and some epoxy.
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freddich
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Re: Best mounting method for aftermarket barrel for PP700?
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Reply #73 on:
June 11, 2021, 02:40:22 PM »
I made a little steel cap to put on the breech block, and fired the first shot string through the crony. Results are pretty decent. For some reason there is a pretty significant dip in performance right around the middle of the series of shots though, does anyone know why that might be?
The last 3 shots or so of the shot string were probably at a slightly lower-than-reg pressure because I was approaching 150bar, so I'll be lowering the regulator slightly and see if I gain any performance. This also leads me to believe the underpowered shots in this shot string might have been due to slightly elevated pressure.
*This test was done with JSB knockout slugs in 25,39gr. With 34grain pellets it made over 50J
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Ribbonstone
GTA Senior Contributor
Posts: 12030
Re: Best mounting method for aftermarket barrel for PP700?
«
Reply #74 on:
June 11, 2021, 02:45:43 PM »
Given the average guy's owner ship of ONE...how many times to you thing a guy will mount a barrel...remount a barrel...re-re-mount a barrel?
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Louisiana
freddich
Shooter
Posts: 75
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Re: Best mounting method for aftermarket barrel for PP700?
«
Reply #75 on:
June 11, 2021, 04:23:31 PM »
Depends how long of a barrel it is. With a longer barrel I can see how it might be convenient to be able to take off the barrel without tools..
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freddich
Shooter
Posts: 75
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Re: Best mounting method for aftermarket barrel for PP700?
«
Reply #76 on:
June 12, 2021, 04:34:59 AM »
Decreased the reg pressure a little bit to 140bar, and put a bit less tension on the hammer spring. With this setup I'm getting pretty much exactly 230m/s, or 755fps with the 25.4gr slugs which I'm pretty happy with. It also seems to have decreased the extreme spread by quite a bit.
It remains to be seen whether the slugs are accurate at all in this barrel, as 750 fps is pretty slow for them.
Now all I have to do is make a bigger plenum.. Which, unfortunately, I don't have the tools to do at the moment..
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freddich
Shooter
Posts: 75
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Re: Best mounting method for aftermarket barrel for PP700?
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Reply #77 on:
June 12, 2021, 08:31:43 AM »
Did a full shot string of 20 shots, but keep in mind that I had to fill the gun half way through. Furthermore as the bottle I use to fill the gun is only at about 210 bar at the moment, I can't fill it quite until full, so this is only in the range between slightly below 210 to 140bar. It does about 13 shots from 210, so at 230 it should probably do 15 shots.
My gut feeling about the reduced extreme spread at this lower pressure turned out to be true, and has seen a significant improvement since last time time. Shot number 6 does bug me though...
Overall, if I can get rid of the weird dip in the middle, this is performance I'm very happy with!
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darkcharisma
Expert
Posts: 1517
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Real Name: duy
Re: Best mounting method for aftermarket barrel for PP700?
«
Reply #78 on:
June 12, 2021, 12:16:33 PM »
If you have a lathe. making a plenum is easy. you should start thinking about where to mount the ppenum. on the side as a standalone or making a tube spacer
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freddich
Shooter
Posts: 75
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Re: Best mounting method for aftermarket barrel for PP700?
«
Reply #79 on:
June 12, 2021, 12:27:00 PM »
Unfortunately I *probably* don't have access to a lathe anymore. In any case I'd probably put it where I put the reg pressure gauge, facing downwards just in front of the trigger guard.
I don't think it would be too bulky or anything, after all that's where regular firearms have a magazine..
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Best mounting method for aftermarket barrel for PP700?