New build

[temchik]

Ok, I found the culprit of the 20fps loss... Drumroll.... it's the extended probe! Put the stock probe in and re-gained it back to stock performance. I think I can explain the physics of it, correct me if I'm wrong:

Extended probe creates a larger chamber and, while it is good for CO2 to create more room to expand, it is detrimental to HPA because it now needs to pressurize more volume in the chamber. You can dump more air, but you are loosing performance at the same pressure level compared to the shorter probe

ETA: so... effectively, I probably added to the longevity of the gun by installing the FT piston/valve and the solid pin, but, honestly, unless you routinely pump beyond 10 pumps I see ZERO reason to upgrade stock parts. If anything else, stuffing the piston will give your better performance at stock number of pumps (I just tried putting about 1/2" RG59 cable piece inside the valve spring and gained about 25fps at all levels. I took it out for now, will find a nylon rod instead)

[temchik]

Received Alchemy Fiber Optic front sight and A.C. trigger spring with guide. The gun is ready

[Trophyhunter49]

  Click onto this link and look at what WyoMan done to his valve. He's one of the best at getting power out of a pumper.

  https://www.crosman-air-pistol-owners-forum.com/board/index.php/topic,11146.0.html
Maybe this will help you out. I have done the same tings to my 1322 before I went to the DARK SIDE !!

[arkmaker †]

Ok, I found the culprit of the 20fps loss... Drumroll.... it's the extended probe! Put the stock probe in and re-gained it back to stock performance. I think I can explain the physics of it, correct me if I'm wrong:

Extended probe creates a larger chamber and, while it is good for CO2 to create more room to expand, it is detrimental to HPA because it now needs to pressurize more volume in the chamber. You can dump more air, but you are loosing performance at the same pressure level compared to the shorter probe

I don't think it is because it is an extended probe that you lost fps. Just doesn't make sense to me. The extended probe tip itself is taking up more room than a stock probe tip (or pretty close to equal the volume).

It could however be the bolt itself is not sealing properly when you did the change over and you are losing air at the seal. Sometiimes you need to reset your barrel back again when you change bolts because the length from the sealing oring to the bolt handle may vary a little.

Not always plug and play with the custom parts. I know that on my 1322 that when I changed from a stock to an extended probe, I got a jump up of about 7-8 fps, not a drop.

[BillK]

Ya know, that made me scratch my head also.  I just never heard of an extended bolt causing a loss of power.  Usually, just the opposite.  When the pellet is seated past the transfer port it does not create any obstruction for the propellant, weather it be air or CO2.  Any obstruction in the propellant path will slow it down.
Extended probes also seem to help accuracy by seating the pellet firmly in the rifling consistently as opposed to getting blown into the rifling at different angles.
I think Rich has the right idea as to the reason the probe caused a loss of power.  It's not the probe itself but the placement of the probe in relation to the barrel.  Just might need a larger Oring....    

[temchik]

Ok. I am done with the 1322. I have tried some mods on it and NONE of them were worth the trouble or money:

- Flat top piston/valve from MellonAir: +0 fps compared to stock. +2 pumps full dump compared to stock resulting in 560fps at 16 pumps
- Extended probe: -20fps repeatable loss, whatever the reason is.
- Weaker valve spring, virtually no change in pumping effort or performance, +0 fps, +(idon'tknow) how many pumps, stopped at 20, full dump, but the same 560fps total.
- Fiber optic front sight from Alchemy - drilled off center, extremely confusing to aim. in the trash it goes.
- Crosman scope adapters - useless as the barrel is not very stable with the stock breech. Don't bother.

What worked:

- polishing trigger parts, lighter spring/guide from AC

In comparison, my first 14.5" custom shop 1300 shoots 600fps at 14 pumps with stock everything. I am not planning on shooting it at 14 pumps, it will be reserved for emergency hunting, so I am not worried about extra wear.

The lesson here, at least for me, buy a custom shop with longer barrel and don't attempt to mod anything for power, you won't get much (if anything at all) compared to stock. Crosman seems to have updated the piston, reducing the head space

Cheers

[JMJinNC]

There is a thread on here that shows what someone did to get his pumper set up for minimum pumps (I think it was 3-4) and shooting speeds for 10M target. If that is what you are after, then that post might be of help long term. I will try to find it and post the link.
Rich

EDIT: Here is the link.......
https://www.crosman-air-pistol-owners-forum.com/board/index.php/topic,4088.msg40044.html

Also, take a look at WyoMan's Stickies in the pumper section for even more ideas

Rich and temchik,

I also did this mod (valve volume reducer plug) to my 10M multi-pump, which does 465 fps at 3 pumps (.177 RWS 7.0gr Basics).

I'm also surprised that the extended probe and FT setup did not yield performance improvements.

JMJ

[temchik]

I forgot to mention the valve plug, did that. Gained +20fps on 3 pumps to the total of 320fps. +0 on full power

[temchik]

Re-cronied, FT piston and valve, lighter valve spring, valve plug, stock bolt/probe and stock everything else:

3x - 310fps
5x - 490fps
10x - 500fps
15+ - 560fps

I guess I could reach 600fps on over 20 pumps, but have no interest in doing so

NO change from stock whatsoever ETA: well, I can pump more than 15 and the best change so far is a smoother shot cycle due to the debouncing effect of the lighter valve spring. I'll take it, just wish I didn't spend over $100 extra for this gun to just get that

[arkmaker †]

I wonder if you are having any hammer drag? Sometimes the sear can drag on the hammer if the overtravel screw is not backed out enough. That can restrict performance and a lot of folks never look for that.  Not sure, just throwing stuff out there, but it sure seems like you should be getting better numbers  with everything that you have done.   

[temchik]

Nope, no overtravel screw on stock 1322 or 1300kt

I wonder if you are having any hammer drag? Sometimes the sear can drag on the hammer if the overtravel screw is not backed out enough. That can restrict performance and a lot of folks never look for that.  Not sure, just throwing stuff out there, but it sure seems like you should be getting better numbers  with everything that you have done.