Air Gun Home :: View topic - Never really found a solid answer about 2240 hollow probe bo

Remtom1200 · Member

Has anyone found an answer to which bolt design for the 2240 has most pro's. I personally always made extended probe just passed the tp. The more I look at that hollow probe bolt the more I think it should be more consistent? Plz give any test results cause I am right here between a new hollow or probe that fits without play in the breech.At this point it can be either depending on which is best.

DavidSaunders · Veteran Member

I do not have any comparative testing, as my hollow probes were made by Crosman for the 140, and are still in the 140.

Though it does seem that the hollow probe would be better. The air flow would not be disturbed as much coming into the barrel.

Remtom1200 · Member

I would do my own test, only I'm sure someone has been down this path.

lampy · Veteran Member

I don't recall ever seeing a comparison done. I have used the hollow probe in a couple builds because I like the way it pushes on the edge of the skirt instead of inside of the skirt.
What kind of data are you looking for? Changes in accuracy or changes in fps?

AirGunEric · Site Admin

Bob did alot of testing of hollow probes a few years ago and found that except at the extremes- i.e. .22 caliber, 24" barrel, other valve improvements, the hollow probes did not gain anyone anything. In fact, on .177 caliber setups they actually reduced power output. I'm sure it's around here somewhere...

lampy · Veteran Member

I would assume that the hollow probe would be restrictive as it adds another opening/ port that the air has to pass through. I don't have any data to back this up, just an assumption. I just like the way it pushes the pellet into the breech more smoothly than a pointed probe.

Remtom1200 · Member

I finished my hollow probe. Its installed and feeds every pellet even. If the fps is lower I will adjust. Something I was able to do while was seat the bolt and drill accurate as well as play with depth to make a forward dome within. I drilled the port towards the barrel and drilled the probe just as it met the intersection. Finished it with the dremmel and engraving bit. Smooth as whatever is smooth..lol. With this setup there is no space between the beginning the TP at all. When you look from the bottom of the breech bolt closed it is the size of the TP curled forward. Good job and no matter what brand and size pellet it will have the same starting point. I am passed novice, and under professional so do what works best for yourself.

Alstone · Moderator & Site Supporter

I have tried both methods and found no difference in power output, but has Eric says with .177 calibre the gain would be small.
Personally I prefer the probe method.

Al

Remtom1200 · Member

Yeah noticed a lil skirt scrapings with the predators. Also noticed the points are glued random so fail!