Beeman P17 and XSP 120D... Next level builds/mods.



Author Topic: Beeman P17 and XSP 120D... Next level builds/mods.  (Read 123220 times))

Offline Bob H.

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Re: Beeman P17... Next level builds/mods.
« Reply #40 on: July 06, 2013, 07:40:26 PM »
Eric,

That powder coating does look good!  Have you spotted much difference between your P 17 specimens?  BTW, are significant design differences between a P 3 and a P17?  I was talking with a friend last night and he had taken delivery of a P 17 this week.  He really likes the way it shoots and now is thinking about a P 3. 

I wonder what the increase in compression and velocity did to the cocking effort?

Please keep updating us on your progress, it is very interesting.

BTW, I have a new project.  I'm cutting the bottom one half inch off of a beer can using CPHPs and my P 17 at 10 meters.  This make take a few more pellets, metal removal the fun way.  Why, because I can.

BobH.
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Offline stalwart

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Re: Beeman P17... Next level builds/mods.
« Reply #41 on: July 06, 2013, 08:23:32 PM »
The first one was the plain sight, had been decently lubed (with something, or another). The FO models were dry, and had been molded with a slightly better match... much easier to smooth.

At max compression the effort is just barely noticeably more, and the speed is up a touch. Nothing amazing.

As I understand there are no differences except fit and finish. I'd like to own a P3, but wouldn't spend much.

Drilled and tapped for a barrel set screw, and while I was at it, did an off center set screw hole to retain the pivot pin. I'm sick of the clips... as often as I pull these down, they've become a real pain.

Offline stalwart

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Re: Beeman P17... Next level builds/mods.
« Reply #42 on: July 06, 2013, 10:18:41 PM »
8 3/4" barrel.


Just chrono'ed... I'm thrilled. This barrel is cut to be halfway between the 10" and a flush muzzle. It has a crack to it (the 10 sounds silenced... quietest I've shot since my first gun, a Daisy 25 BB gun). Low: 313.5, High: 318.3, Av: 314.7, ES 4.8 (edit...  didn't make sense)

The test gun ran 9.25gr .177s at 390. It is well broken in, and very consistent. The superb ES is a result of a consistent barrel and powerplant in the same gun.

10" barrels are not a waste of space in these, after all. Judging by the sound difference, I'd guess that a 12 might show little worth. I'll try it when the carbine gets underway.
« Last Edit: July 07, 2013, 03:35:01 PM by stalwart »

Offline Bob H.

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Re: Beeman P17... Next level builds/mods.
« Reply #43 on: July 07, 2013, 08:38:13 AM »
8 3/4" barrel.


Just chrono'ed... I'm thrilled. This barrel is cut to be halfway between the 10" and a flush muzzle. It has a crack to it (the 10 sounds silenced... quietest I've shot since my first gun, a Daisy 25 BB gun). Low: 313.5, High: 318.3, Av: 314.7, ES 6.75


Eric,
Those numbers are nice! If I remember correctly that is a 1 in 16 twist, I'm really interested in the groups that you will get out to 30 yards and what the trajectory will be.  I'm really thinking about a "friendly" .177 with a similar velocity.

Guys, this is a great build! Eric, you have made some great decisions and have done your research.

BobH.
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Offline stalwart

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Re: Beeman P17... Next level builds/mods.
« Reply #44 on: July 07, 2013, 11:29:19 AM »
Thanks, Bob.

Yeah, 1 in 16. It doesn't always hit where I want it to, but this one does hit where it was pointed when the trigger was squeezed. I need practice...lol.


I think the rings in #1 are going away. Just lubed it after leading up the barrel, and got these: High:342.5, Low:339.3, Av 341.2, ES 3.22

Looks like I'll have to rethink barrel length. I'll have to test with both lengths in the same gun, to be sure... but, it looks like 8 3/4 may be a sweet spot.
« Last Edit: July 07, 2013, 03:12:19 PM by stalwart »

Offline stalwart

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Re: Beeman P17... Next level builds/mods.
« Reply #45 on: July 08, 2013, 06:55:48 AM »
#1 had the least compression of the 3, and as I'm going to use it to test barrel lengths for efficiency I went ahead and stuffed it. It really stiffened up the cocking effort... I'm guessing that when it's chrono'ed, it will show.

For those who are contemplating doing a trigger job, I highly recommend making the oversize trigger pin first. #1 is set up with my best single stage, and as I have posted, I had to give up (allow) some creep to get a solid safety engagement (a hard squeeze would set it off, if set to it's finest). It now has less than a mm of travel (there is no such thing as "zero creep"... only that which is less than the space it takes to compress your fingertip, and therefore cannot be felt, only seen). I now cannot squeeze it hard enough to get it to fire on safe.

You won't need to precisely measure the pin. Just polish something down until it will fit the trigger's hole with resistance, and lube it to free it up. The results are superb.

FPS when the light is right.


Got a high of 351.1, and a low of 339.3, with an 11.8fps ES. The higher compression is causing a wider range of cocking efforts and speeds. Anyone here have experience with various types of O-rings in these? Seems the stock piston rings are good for about 1000 cycles before consistency suffers... no surprise as they add a black dust to the lube throughout their use.
« Last Edit: July 08, 2013, 10:49:53 AM by stalwart »

Offline Bob H.

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Re: Beeman P17... Next level builds/mods.
« Reply #46 on: July 08, 2013, 11:08:31 AM »
What are the issues in using a "cupped" seal?  The piston looks simple to replicate.  Back in my old two stroke motorcycle days there were "dykes" piston rings.  I think you could form a leather seal that might work.  What do you think the current chamber pressure is?

A leather seal would need to be bound to  or by the piston, just thinking out loud.

BobH.
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Offline stalwart

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Re: Beeman P17... Next level builds/mods.
« Reply #47 on: July 08, 2013, 12:51:47 PM »
They can deform enough to be inconsistent. I'm not worried about anything but consistency... I'm convinced (atm) these can be made into serious target guns.

I went to a Viton 75 duro ring. The stockers are soft, too, and the most wear is at the intake hole (no surprise). New #s: 341.6L, 350.1H, 345.1av, 8.80ES. If this ring only lasts 1000 cycles, I'm fine with that.

#1 has not been ported (@2.5mm), that should put it solidly at 350+fps with 14.3gr CPHPs. Not bad.

I haven't calculated the pressure. I'm very interested in the ES numbers you get with the reduced compression.

Offline stalwart

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Re: Beeman P17... Next level builds/mods.
« Reply #48 on: July 08, 2013, 09:32:50 PM »
Prepping to cut a 7-1/2" barrel (flush with the nose), will have solid #s on 1-1/4 increments soon. Borrowed my girl's upper to run #1 with it's original .177 barrel (a consistent 9.25gr @ 390fps). At full compression with stock port: H: 401.4, L:392, Av:396.5, ES: 9.4. No surprises there...


Barrel's cut.  H:330.8, L:315.6, Av: 321.1, ES: 15.19... 14.3gr CPHP. ~25fps less than 8-3/4"
« Last Edit: July 09, 2013, 12:31:20 AM by stalwart »

Offline stalwart

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Re: Beeman P17... Next level builds/mods.
« Reply #49 on: July 09, 2013, 02:22:33 PM »
Here's the #s for the 10" (not that anyone asked...  ;D):

H:344.5, L:338.0, Av:341, ES:6.54

Looks like 8-3/4" is the ticket for .22. 4fps less than 10"... 25 more than 7-1/2". The 10 is very consistent, though... and amazingly quiet.

If anyone has an 18"+ .177 barrel, in decent shape, they want to sell... I'd like to run these lengths through the chrony.
« Last Edit: July 09, 2013, 03:02:10 PM by stalwart »

Offline Bob H.

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Re: Beeman P17... Next level builds/mods.
« Reply #50 on: July 09, 2013, 03:42:38 PM »
I chronographed  (10) shots from the reduced compression P17.  The high velocity was 375.3 and the low velocity was 362.9. The extreme spread was 12.4 and the average was 368 FPS.

The velocity is up on average of 15 FPS since I last chronographed it, perhaps the additional shooting has smoothed the barrel.  The pellets were Crosman Premier hollow Points.

BobH.
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Offline stalwart

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Re: Beeman P17... Next level builds/mods.
« Reply #51 on: July 09, 2013, 04:55:22 PM »
Thanks, Bob. That's with the .040" dish, correct?

The speed increase is partially leading, but I'd bet lunch you have hit the sweet spot on the stock o-ring. They become very good, and consistent just before they wear out. How many rounds went through it so far?

The Viton ring in #1 got sweet in a hurry (genuine, MSC), and judging from the contamination of the grease (black tint) it is wearing very little compared to the stocker. It's 75 duro, and I went with a #117... same dia but thicker (the groove was generous). It holds full compression, so is hard to cock... it looks like, when broken in, it will hold single digit ESs.

How is the detuned rig handling? Sweetie like it better? That's not a huge loss of speed. According to the Beartooth calculator, you are still carrying in the range of 2FPE. I asked in the Airgun gate what was the min FPE useful in 10M pistol, and got crickets... we'll have to figure that out. All I know right now is that reduced pressures can help lead to real consistency... leaving us only a good barrel away from real precision.

I really appreciate your data. Please keep them coming. I intend to follow your numbers, and then log mine for comparison... I want to build my girl the very best pistol I can, she has been very supportive (again... as usual).

Offline Bob H.

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Re: Beeman P17... Next level builds/mods.
« Reply #52 on: July 09, 2013, 05:48:49 PM »
That's with the .040" dish, correct?

stalwart,

It took me awhile to comprehend the .040" dish.  The decompress is as I remember .065" deep after the second trip to the lathe and the max. dia. is .900" .  Sounds like my O ring is gonna die ,,,,soon. The O ring may have have 1300 plus cycles.  I do keep the piston greased and the breech O ring shinny with oil.,,,,,,,,,,,,,,,,,,,, Think I'll go kill a can, I need a pellet fix.

BobH.
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Offline stalwart

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Re: Beeman P17... Next level builds/mods.
« Reply #53 on: July 10, 2013, 01:19:02 AM »
You may get better wear. #1 is an earlier (non FO) model, and may have cheaper rings. Are you getting a lot of black dust mixed into your piston lube?

The Viton ring is leaving much less, and getting better with age.


Offline stalwart

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Re: Beeman P17... Next level builds/mods.
« Reply #54 on: July 10, 2013, 02:09:58 AM »
http://www.network54.com/Forum/275684/thread/1305736542/Beeman+P-17+multi-stroke+finished!

"Factory Valve volume: .047 cu.in. Factory Pump sweep: 3.1 cu.in Factory PSI: 969 psi

Mod Valve volume: .081 cu.in. Mod pump sweep: 2.74 cu.in. Mod psi (pumps): 1. 497 psi, 2. 994 psi, 3. 1491 psi " I'm betting this guy's #s are good.

Going with rsterne's "1cc per FPE" plenum rule of thumb, I'm working on a somewhat different MSP valve. Both .22s are hitters, and there is no speed left in blueprinting. I want a fast one.


http://www.gatewaytoairguns.org/GTA/index.php?topic=48729.msg459960#msg459960  Made another, of a better size.
« Last Edit: July 10, 2013, 03:51:39 AM by stalwart »

Offline stalwart

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Re: Beeman P17... Next level builds/mods.
« Reply #55 on: July 10, 2013, 09:03:55 AM »
Had a little fun on the mill. Cut cleaner serrations in the trigger guard, and indexed then epoxied a bit of picatinny rail where it won't get in the way of a longer barrel.

Offline Bob H.

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Re: Beeman P17... Next level builds/mods.
« Reply #56 on: July 10, 2013, 09:55:49 AM »
stalwart,

This is interesting, are you preparing for a laser?  I was meaning to ask,"Where did you purchase the Picatinny rail?"  What epoxy are mounting the rail with?  Most of the force applied to the milled portion of the frame is linear, do you anticipate any flex while closing the action?

If you are under mounting a laser, the trajectory and line of sight will  converge and cross only once.  This is one of the things that I'm rolling around in that empty space behind my ears, "Do I want it to cross twice?"

Please continue to keep us in the loop, this is exciting stuff.

BobH.
  • central Illinois

Offline stalwart

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Re: Beeman P17... Next level builds/mods.
« Reply #57 on: July 10, 2013, 09:13:03 PM »
I'm just messing around while I wait for the next 2 to get here. I used JB, so I can't twist it until tomorrow... but, if it fails, I cut an index tab into the rear of the rail, so 1 t-nut at the front will hold it.

Got the rail on ebay for $13.

Offline Bob H.

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Re: Beeman P17... Next level builds/mods.
« Reply #58 on: July 11, 2013, 11:06:31 AM »
stalwart,

Seeing how I'm lazy, a question, do you have a dimensional description of the (4) O-rings that are used in the P17?  I would like to buy a small supply of them to have on hand.  To date, the only O-ring that I have replaced is on the valve.  More replacing will be a fact of life. 

The P17 has turned my 717 Daisy and my 2240 into closet princesses.  (they have lost their closet queen status)

I keep telling myself that I don't need a 22 caliber P17 special, but part of me says "That's a lie!"

Keep up the good work! and please keep us posted.

BobH.
  • central Illinois

mrb02334

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Re: Beeman P17... Next level builds/mods.
« Reply #59 on: July 11, 2013, 11:20:24 PM »
The P-17 is a great pistol, I wanted to convert two to 10" barrels. One .177 and one to .22. So who can machine the barrels for me? Please pm me.
Thanks,
Jon

GTA - What's been your success with air gun target practice?