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timefreak17 01-06-2013 12:17 PM

Sheridan PMI-II help
 
3 Attachment(s)
I am a new brass owner and have run into a few problems.

I have a back bottle setup and i am running into velocity problems. How do i adjust the velocity?

Also i don't have a tool to really tighten the square nut in the lower body.


Attachment 36882

This is after I cleaned it up, reworked the brass tube to not lock up on the forward pump stroke, and put in some new pieces.


Attachment 36883



What it looked like before.
Attachment 36884

Any info or help is welcome.

MrBig 01-06-2013 12:23 PM

Not a lot of choices for velocity on a back bottle Sheridan. You can shim your main spring or get a rear velocity adjuster put into your BBA. Or, find a Cooper-T BBA with built in velocity adjuster.

Someone on here was offer the service of adding a vel adj to Sheridan BBAs, if I recall correctly. I don't believe they were asking much for the service either.

big jim 01-06-2013 12:35 PM

Mr. Big is correct. Without a Cooper-T rear ASA the best answer os to shim out the main spring. Simply place a shim of some kind behind the main spring in the rear plug, I have used spit wads in a pinch.

Long Beard 01-06-2013 02:11 PM

there's another option....there was a velocity adjust hammer that I believe PPS did back in the day. It had a ball bearing in the hole of the hammer and an allen screw that was accessible through the slot for the bolt.

I do believe if you wanna do a velocity adjust on your BBA, WALZ does those. Something to check out at least.

Also: I believe Titus has valve tools to tighten the squared off screw inside the lower tube. You can check with him.

MrBig 01-06-2013 03:13 PM

Quote:

Originally Posted by Long Beard (Post 2583989)
there's another option....there was a velocity adjust hammer that I believe PPS did back in the day. It had a ball bearing in the hole of the hammer and an allen screw that was accessible through the slot for the bolt.

I forget about those. I actually have one down in my Sheridan parts. Instructions and all. :)

timefreak17 01-06-2013 03:36 PM

Thanks so far for the insights. Right now im using a make shift square key.
I will see what shimming does as a quick fix.

What is the main spring? the one that pushes the hammer...or....the spring pushing against the valve guide?

But how does the airflow work?

Could it be the screws with the air holes in them on the side of the marker? i know the holes dont line up perfectly and they are a corroded.

MaD 01-06-2013 09:48 PM

You using Co2 or HPA?

Long Beard 01-07-2013 12:03 AM

The main spring is the one that pushes the hammer. The other spring is called the valve spring.

air flow. hammer hits valve releases air that goes up tube through bolt and pushes ball.

the air screws shouldn't impact much unless there is a blockage or a leak at them.....so I doubt it.

what square screws are you talking about? I thought you were talking about the valve retaining nut. are you talking about the air screws on the outside? those are suppose to be allen screws....they could be stripped.

timefreak17 01-07-2013 12:33 AM

using hpa. I was talking about the valve retaining nut.

Does the valve retaining nut contribute to controlling velocity?

Brassballs 01-07-2013 08:55 PM

the valve nut is not going to affect/adjust the velocity.
it just holds the valve in and compresses the o-rings.

the easiest way to bring it up to speed will be to shim the spring and hope it's right or drill & tap or buy a BBA that you can adjust with a allen key.


also your HPA reg needs to be set for high output. 800ish
these old untuned sheridan's work best on CO2


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