p15 testing with and without valve return spring

[swish]

I kinda like option 1 and wonder if you would even need to plug the original hole if it was turned up to 12 o'clock. It seams like as long as the pellet slid past it ok you'd be fine.

[mackeral5]

I appreciate the input.  Options 1 and 2 have their merits and challenges.  Option 3 I believe is the least attractive if only due to the potential of an unnecessarily oversized barrel port. 

The way the p15 js assembled creates some challenges for option 2--- by moving the barrel back it would also require a dimple in the barrel to be oblonged so that the scope rail assembly (and forward stock mounting hole) doesn't move rearward as well.  This dimple locates a set screw in the rear barrel band. 

Option 1 will require 3 steps.  1) Plug the old port.  2)  drill/finish the new barrel port 3) create new dimple on barrel for the set screw. 

Option 2 I am not equipped to do, at least I am not equipped to do it in a manner that is guaranteed to not look poorly.  I can make it work, but it is going to be ugly

Option 1 I can do and have done before.

Before making a final decision. I need to mock up the bolt/sidelever in the monoblock.  I need to ensure the bolt and transfer port are properly oriented----- if the transfer port is forward of the bolt this will bring another variable into the mix...... In hindsight I should have checked this first and i wouldn't have had to reassemble the bolt and sidelever.

This is one example of how SPA can cram so much value into a $600 gun...most owners would likely never known any different.  Once resolved it will be  one more bit of satisfaction I'll get from my P15 experience---we all buy these guns for different reasons.  I tend to enjoy this aspect of it.  Let's hope I don't make any mistakes and can simply execute on a plan.

BTW, I just realized how many pellets and how much nitrogen I've wasted collecting BAD data.  I can only roll my eyes and laugh at myself for not finding this sooner.  I was in to big of a hurry trying to make the p15 "better" and failed to make sure it was "right" to begin with.  Hopefully at age 45 I've learned this lesson for the last time.  Something tells me I haven't, lol.

[swish]

Don't forget, you can just put a new dimple in the front barrel band instead of the rear one. I put a set screw in the forward one just cause. Even without a dimple.
Besides if you spun the barrel 180 you'd have a new spot for a new dimple anyhow.

[Pelletjunkie]

I would move the whole barrel to the rear. Here is why. My P15 had accuracy issues that were solved when I seated the pellet deeper than the probe would. I have been following your P15 threads and I never read anything about how accurate your gun is. You have been chasing power and efficiency and it would be a shame if you found what you are looking for only to have a gun that shoots like a shotgun at 50yrds. Your gun can only benefit from having that pellet seated a little deeper into the rifling.

[swish]

I would move the whole barrel to the rear. Here is why. My P15 had accuracy issues that were solved when I seated the pellet deeper than the probe would. I have been following your P15 threads and I never read anything about how accurate your gun is. You have been chasing power and efficiency and it would be a shame if you found what you are looking for only to have a gun that shoots like a shotgun at 50yrds. Your gun can only benefit from having that pellet seated a little deeper into the rifling.

I agree. I was leaning towards option 1 because of being easier to do. After reading the post I checked mine immediately. The back of a cphp is flush with the edge of the transfer port. It doesn't feel like it seats the pellet head very well.
Mine shoots about 1" groups off the bench at 55 yards with 16grn JSB's. Most of them land in about 1/2" so I will definitely run some accuracy testing soon with seating the pellets better. I may have to end up needing to adjusting my barrel as well.

[mackeral5]

I would move the whole barrel to the rear. Here is why. My P15 had accuracy issues that were solved when I seated the pellet deeper than the probe would. I have been following your P15 threads and I never read anything about how accurate your gun is. You have been chasing power and efficiency and it would be a shame if you found what you are looking for only to have a gun that shoots like a shotgun at 50yrds. Your gun can only benefit from having that pellet seated a little deeper into the rifling.

I agree. I was leaning towards option 1 because of being easier to do. After reading the post I checked mine immediately. The back of a cphp is flush with the edge of the transfer port. It doesn't feel like it seats the pellet head very well.
Mine shoots about 1" groups off the bench at 55 yards with 16grn JSB's. Most of them land in about 1/2" so I will definitely run some accuracy testing soon with seating the pellets better. I may have to end up needing to adjusting my barrel as well.

Sounds like good advice to me.  I chose option 2.  Point well taken regarding accuracy.  All of my posts for the past year or so have been around tuning for efficiency at a given FPE.  Currently life doesn't allow for much else, so accuracy is taking a back seat at this time.  At some point I'll get to spend more time focusing on targets and less on the chronograph. 


I had to determine the best way for me to perform option 2 with my current abilities/tooling.

i made a slight change to the breech/monoblock-  a slight countersink added to the breech to allow the shoulder on the barrel to recess a bit into the breech, resulting in the barrel sitting a bit farther back.  Now a drill bit inserted from the transfer port hole fits perfectly in the barrel port when the barrel is fully seated.  pellets seat just past the parrel port now.  It is virtually unnoticeable when assembled.  I machined the rear of the barrel flush with the breech by spinning it in a drill while running it against my 1" wide vertical belt sander--it's a WorkSharp knife sharpener sees a lot of uses other than sharpening knives.  Using this method I ended up with a perfectly smooth and square finish. 

I hope to reassemble and have some test results to post later this evening. 

[swish]

Great idea on the countersink! I think we may be working out of the same machine shop. Lol.

[Rallyshark]

I would move the whole barrel to the rear. Here is why. My P15 had accuracy issues that were solved when I seated the pellet deeper than the probe would. I have been following your P15 threads and I never read anything about how accurate your gun is. You have been chasing power and efficiency and it would be a shame if you found what you are looking for only to have a gun that shoots like a shotgun at 50yrds. Your gun can only benefit from having that pellet seated a little deeper into the rifling.

I agree. I was leaning towards option 1 because of being easier to do. After reading the post I checked mine immediately. The back of a cphp is flush with the edge of the transfer port. It doesn't feel like it seats the pellet head very well.
Mine shoots about 1" groups off the bench at 55 yards with 16grn JSB's. Most of them land in about 1/2" so I will definitely run some accuracy testing soon with seating the pellets better. I may have to end up needing to adjusting my barrel as well.

Sounds like good advice to me.  I chose option 2.  Point well taken regarding accuracy.  All of my posts for the past year or so have been around tuning for efficiency at a given FPE.  Currently life doesn't allow for much else, so accuracy is taking a back seat at this time.  At some point I'll get to spend more time focusing on targets and less on the chronograph. 


I had to determine the best way for me to perform option 2 with my current abilities/tooling.

i made a slight change to the breech/monoblock-  a slight countersink added to the breech to allow the shoulder on the barrel to recess a bit into the breech, resulting in the barrel sitting a bit farther back.  Now a drill bit inserted from the transfer port hole fits perfectly in the barrel port when the barrel is fully seated.  pellets seat just past the parrel port now.  It is virtually unnoticeable when assembled.  I machined the rear of the barrel flush with the breech by spinning it in a drill while running it against my 1" wide vertical belt sander--it's a WorkSharp knife sharpener sees a lot of uses other than sharpening knives.  Using this method I ended up with a perfectly smooth and square finish. 

I hope to reassemble and have some test results to post later this evening.

Awesome, I look forward to seeing how it works out!

Great idea on the countersink! I think we may be working out of the same machine shop. Lol.

A lot of us are working out of that machine shop

[mackeral5]

It is amazing how easy the p15's monoblock design js to disassemble and reassemble.  No need for a ramrod unless the reg wasn't secured right enough to the plenum, which is an easy thing to prevent.    I didn't have much time, but initial results look to be a slight improvement.  Clambering a pellet feels different now. 

I have a love/hate relationship with that machine shop.  I dont think I would refer any business there, but I keep going back, lol