First PCP, lots to learn, need advice and guidance
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First PCP, lots to learn, need advice and guidance
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Topic: First PCP, lots to learn, need advice and guidance (Read 269 times))
point177
Plinker
Posts: 119
yes
Real Name: Manish
First PCP, lots to learn, need advice and guidance
«
on:
December 06, 2021, 05:19:56 AM »
Hi All,
Put together my first PCP using a Safepac. Filled it with between 1800 and 1900 psi.
Did'nt check number of shots in the excitement but I think got about fifteen of them. Highest FPE recorded was with local 8.7grain dome heads.
I understand shot count will not be high owing to size of reservoir.
Here is what went into the build.
- 24in barrel
- standard 2240 valve and transfer port.
- Power adjuster with 1377 hammer spring
Being a newbie to PCP, looking for guidance to get consistent fps as much as possible but have no clue as to how to go about it.
Also have some things that I want to sort out.
The barrel goes slightly to the right, any way I can correct that ?
Barrel bands : Are two needed ? any way those can contribute to straightening of the barrel without bending the barrel permanently ?
Am I missing anything else ?
Thanks for help.
Manish
«
Last Edit: December 06, 2021, 05:27:26 AM by point177
»
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India
Ribbonstone
GTA Senior Contributor
Posts: 12030
Re: First PCP, lots to learn, need advice and guidance
«
Reply #1 on:
December 06, 2021, 12:07:53 PM »
While not quite the same, this might help.
Honestly, as a learning exercise...the conversions are a help. Getting one together and running right will definitely teach the basic Pcp relationships.
I liked my “skinny crutch” conversion assembled on a 2240 tube. Did manage to put tougher light weight, decent power, but be kind of awkwardly long.
bd432f6b-73e9-4868-ab36-c843cda65c03 (1)
by
Robert Dean
, on Flickr
In the above picture, had a short conversion tube and made a slip on fore end from a pump-paintball fore end. So I also used the front band to hold the fore end in place.
Butt stock also salvaged paintball part...no idea who made it or what it was made for, but a dimensional fit...had to drill and tap screw holes to make it work.
-----------------
Your HPA conversion tube is different…it’s a better design. Can eyeball it as see it has a larger volume, Would stay inside their recommended pressure (think that is 1800psi recommended/ 2000psi max).
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Don’t know for sure the barrel is bent. The Crosman breech has a small contact area with the tube and is easily misaligned. Just a little too high a transfer port, or the port’s o-ring not quite seated, or just the “slack” in the screw alignment can let it sit cock-eyed. JUst a little cock-eyed would show up as a large missalignment with a 24" barrel attached.
Take off the bands and trigger housing. Loosen the two breech screws and the valve location screw. Just gently push down and “wiggle” it to see if there is a spot where it feels like ti is in firmer contact.
Can usually VISUALLY align the barrel in relation to the tube (easier with all the other stuff taken off).
A yard stick or dead straight rod taped to the air tube makes that visual reference easier. Would be trying to even up two equal length parts.
If you think the barrel is actually bent, but you can’;t easily see the bend….will take it off and roll test it (usually on a glass tabletop). Those Crosman barrels are long but skinny, can bend them back into better alignment if they do roll test bent.
Trial and error for the barrel bands. For me (several Crosman projects)...if you use two bands, worked out better for me to have the 1st band right up against the breech.
Shim that rear band tight when the band set screws are loose. It’s main job is to clamp down the barrel and breech. It’s the poor breech retention of the design (small footprint to the tube, horrible tiny front breech screw, breech screws way too close tother). TIGHT before the little retention screw is snugged up (they tend to strip if you tighten them hard enough to act as a real clamp).
I cheated. Didn’t want to run a tight shimmed band all the way down a nicely blued tube to get it in place. So I glued the shim to the tube in the right place (butted up against the breech), so can slide the band easily down the tube, and just barrel get it almost fully back. Might have to tap it back that last 1/8”.
2nd band is used like a normal band. If you want to do anything, make it tight to the air tube, but a tiny bit of slack to the barrel. Seems to solve expansion/contraction issues that way, but still acts as a bumper-guard. Didn’t bother with a 2nd band with pistols.
Adjusting the spring tension to match the air pressure to get a kind of bell curve would be the same as on any non-regulated PCP.
The co2 valve stem/poppet worked for longer than I guessed it would. Piercing pin clutters the air flow, but the softer co2 poppet survived for about a year and a half. 1800psi is not technically out of the materials max, but we tend to store PCP's a higher than co2 pressure, which tends to mash out those soft poppets over time.
---------
Have the same basic air pressure as a Disco/Maxi….same barrel length….could get about the same power (high or low) as either of those, just not the shot count.
«
Last Edit: December 06, 2021, 12:15:22 PM by Ribbonstone
»
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Louisiana
point177
Plinker
Posts: 119
yes
Real Name: Manish
Re: First PCP, lots to learn, need advice and guidance
«
Reply #2 on:
December 08, 2021, 04:31:00 AM »
Hi Ribbonstone
Thanks a lot for the inputs. Will start looking into the points you mentioned on the weekend.
Manish
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India
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First PCP, lots to learn, need advice and guidance