Barrel chamber and port..

[cosmic]

Well I missed something in my pcp education.. I removed my barrel and dropped a slug in it, then a pellet..  I am seeing the middle of them (NSA 15.5 and JSB 13.65 Monsters) through the port..   Is this a problem with the chamber depth ? I did try to push them in a bit .. I was going to open the ports and lo and behold my Nova Vista Liberty .177 Barrel port and power ajuster are bigger then 1/8" (my 9/64th  out 3 sets are in the vast black hole area 51of my storage.) Floods and moving !!  I am even dealing with essential tremors... Anyway thats my question..
                           Thank
                                        Ray

[Nvreloader]

Ray
One way to tell is,
install the bbl back into the action in it's proper place,
then chamber those projectiles,
then remove the bbl and check thru the TP hole,
to make sure the projectiles are seated correctly.

Tia,
Don

[CraigH]

As Don stated, seat the projectile in the assembled top end (breech/barrel/bolt/etc) with the bolt/probe.   Then look in the TP for where the pellet/bullet is seated.   Some airguns are known to require a different probe to properly seat the projectile forward of the TP.

[KnifeMaker]

Or cock the gun after pushing the bullet forward by closing the bolt. Set the safety and  fully draw the bolt back.  Use a dental mirror and light to check if the base is past the port.


Knife

[cosmic]

Well here is my dumb question for the day.. On a normal .177 bolt probe does it enter the back of the pellet some ?
Seems when  I chambered a slug it is quite a bit in front of the barrel port..  Losing pressure due to extra volume ? Do slugs need a shorter bolt probe?
                                 Ray

[rsterne]

You can use a shorter bolt probe with a bullet (slug) than with a pellet, because the probe does enter the hollow base of a pellet to some degree.... As long as the bullet chambers OK, without too much resistance from the rifling, I wouldn't worry about shortening the probe.... as that means you could no longer use pellets, they would occlude part of the barrel port when loaded by the shorter probe....

Although you do loose a small amount of pressure, and a fraction of an inch of effective barrel length, by loading the bullet maybe 0.1" further forward.... in all honesty you probably could not measure the velocity difference.... unless the gun had a really tiny plenum volume....

Bob

[Nvreloader]

Ray

Bob,
Posted before me,
and here is some other info that may be helpful to you.

Take a bunch of your pellets, measure the depth of where the inside pellet base stops, (inside the skirt),
there is NO set standard for this depth, each manufacture has it's OWN spec's.

Do you have a nose probe that pushes on the outside edges of the skirt base,
or a pin type nose probe that reaches up inside the skirt?

Each type of bolt probe chambers differently, depending on their OEM spec's.

I found out, that even if the same company made whatever type of pellets,
there is a difference between brands/types.

Just between these 2- 22 cal pellets, both Crosmans, there is a difference,
the domed head HP pellet measures = .110"
the Piranaha pellet measures =.080",
which is a .030" difference, when measured from the skirt base to the inside top of the pellet waist.

A slug is different also, depending on brand/type etc.
Only testing will tell the difference, the best way is take your bolt,
lay the different type of projectiles, accurately lined where the end of your bolt probe pushes on the slug,
to see the differences etc.

If you only shoot slugs, then you can adjust the bolt probe to fit, BUT, if you change slugs,
you may need to have a different bolt probe length etc.
It will take some careful measuring to find the info, and what will work for you.

I have a post some where here on GTA, where I give the spec's for 25-30 different pellets,
that gives the total overall length, skirt depths, etc.
I'll try to find that info for you, if you want it.

HTH's

Tia,
Don

[cosmic]

Thanks all... I guess I'll chamber a slug and measure the depth to the base and then measure to the front of the port.

[cosmic]

I did have a thought yesterday about sizing (this is a .177 slugs are 4.52).. I chambered the slug and after I removed it fell through the 4.46 spot on my pelletgage.. Measured with micrometer at 4.34 mm ... Best I can do was to set the slug upside-down and slide the micrometer to it.. Essential tremors make it difficult !!!
  The post on this rifle Nova Liberty does say it has a tight bore but it this to much ??

[rsterne]

Probably work fine with pellets, but I would expect slugs to be hard to chamber, although they may shoot fine.... It looks like that slug has been sized by the grooves, the area between the lands is shiny....

Bob

[darkcharisma]

The Ati Liberty has total 10-12cc. Not much and the pellets do seat deeper well past the barrel port...even at .217

I would leave the bolt probe alone until you decide to exclusively shoot slugs.

[KnifeMaker]

Looks like it may be time for a sizing set-up. 

[cosmic]

That what I was thinking Knife..

[cosmic]

Well I tried to enlarge the barrel port without a drill press.. Oversize  a bit but good in the inside (about the right size in the chamber).. Good thing not close to the o rings.. Dammed tremors !!! Dominant hand no less.. At least I didn't cut off a finger ... Tried to pour a cup of coffee Not a good wake-up  with hot coffee covering you!!  Waiting for my receiver to get here .. Well, I realize I can no longer do things without power tools and all mine went down in the flood.. See avatar ...  So I guess I am going to come up with the money for thing like this !!! Receiver is at a friends being worked on.. Great to have friends !!
Thanks Brother !!

[Back_Roads]

 Just a footnote on the Aspen/ Nova Freedom/ Liberty barrels.
The .22 30 gr. BBT cast slugs are not a good match, when slugged, the drive bands were completely removed, causing full contact with the barrel, and too tight to shoot with enough speed.

[rsterne]

Did you purchase the 0.217/0.219" mould…. or the 0.220"/0.222" version?.... I can't imagine a commercial airgun barrel where the groove diameter is smaller than the midbody diameter of the .217" mould, which is only 0.211".... Most airguns use the smaller bullet....

Bob