What does an extended Hollow Probe actually do? Crosman 2240.

[supersharpshoot]

Hi Guys,
Just got my first crosman 2240. Looking at modding it already! What does the extended hollow probe do? looking at getting the steel breech with probe. Thanks.
Also can anyone explain how much difference the power adjuster makes? how many FPS higher and lower each way?

[gingernut]

Makes it more difficult to load a pellet.
No idea on power adjuster.

[short-carabine]

As I understand it, the probe gets more CO2 behind the pellet in the breech. I haven't used one of the hollow probes, just the extended one. It may make a slight FPS difference but not a lot. Steel breech is a good move- seals better and you can fit a scope/dot without mucking about with problocks which move about. The "power adjusters" are only really any use to turn the power down- do them up too far to try and increase it and your Crosman doesn't work well. TBH I found them a waste of time. I found stronger hammer springs a similar waste of time. You can fit a BOSS valve, but I'd tread carefully with a 2240 to avoid going over power. 2250s are less of a problem as they have the 12 Ftlb limit rather than 6.

[short-carabine]

Makes it more difficult to load a pellet.

True!

[TonyL]

I have a 2240, to which I fitted a G-Mac steel breech, extended probe (not the hollow one), shoulder stock and 4x32 scope, making it into a mini-carbine.

The longer probe, as I understand it, seats the pellet a little deeper, sort of pre-sizing the pellet a little, and helping to overcome some of the initial start friction, so maybe raises power slightly. It possibly helps improve consistency a little.

However, especially with the scope on board, the longer probes do make pellet loading a more fiddly affair...I use Hobbies in mine, and I'd hate to think how much more fiddly it would be with a longer bodied pellet.

I'm seriously considering turning it back into a pistol, losing the scope and fitting open sights, probably the LPA MIM one, thus restoring the fun factor of a pistol and also exposing the breech more, making loading easier.

Power adjuster....as above, really. Can't really see the point on a pistol to raise power, as some of the 2240s are very close to the limit anyway.....However, as a means of REDUCING power, and increasing the shot count, that would maybe be an advantage. Or you could just get a spare hammer spring and cut it down slightly.

There is so much you can do to these fine little pistols but my idea of a nice 2240, without going OTT, would be steel breech, MIM rear sight, polish and smooth out the trigger a little, maybe slightly weaker trigger spring, maybe some of those nice screw conversions and maybe slightly weaker valve spring combined with slightly weaker hammer spring. Fitting the slightly weaker valve spring would be the only slightly more involved job, certainly not difficult, though. And everything else is an absolute doddle.

P.S. If I were buying a steel breech conversion today, personally I'd use the original bolt.

[clarky]

The original mod of extending the probe has since been chucked out. There maybe a slight improvement in consistency due to more perfect seating (not completely proven) but it was revealed to lose power. This maybe due to less time in the rifling (less pressure build up) or greater dead space forward of the transfer port.
The best proven system is a shape and length virtually identical to the stock probe but with the angle just behind the parallel section of the probe to be machined parallel or reduced in angle to create more flow efficiency. So flow efficiency is key. I found this to give a nice 25fps to 30 fps increase in the .1377 and 20 fps in the .22 2240. I have not done a 1322
I've tried reducing probe diameter but retaining exact length for similar results but go too small and a small impression gets poked into the ass of the pellet which is isn't a great idea. This occurs because you are not spreading the load of the probe across enough diameter.
So my advice is identical probe diameter and length but angle reduced back to aid flow.....job done.

[archie]

I found the normal pin probe to be the best for pellet seating. I tried the extended hollow probe but it would not seat the pellets correctly and quite often deformed the pellets. I never found the 2240 loading action to be the best anyway, so now have parted company from the Crosman.

[sniper24687066]

According to a seller on flea bay these are supposed to increase power" Crosman Unrestricted Transfer Port Bushing" for the 2240, 2250, 2260, 2289, 1377 or 1322 .
item number: 230883836732 Anyone know if this would work?

[supersharpshoot]

Thanks for all the replies, I think i'll stay with the standard probe for now but I am looking for the steel breech and a silencer. Ordered an adapter for it with a 1/2" unf thread. Then i can nick the silencer off my HW when I go wandering around the sheds... Look out you little rat !!!

[clarky]

Thanks for all the replies, I think i'll stay with the standard probe for now but I am looking for the steel breech and a silencer. Ordered an adapter for it with a 1/2" unf thread. Then i can nick the silencer off my HW when I go wandering around the sheds... Look out you little rat !!!

Except don't do it on really cold mornings. Your power will drop to about 3ftlbs with the gas bulb Crosmans....wouldn't be fair even on rats.
I found the 1377 unaffected by cold temperatures, comfortably hitting high 550s with most .177 8 grain pellets on 10 pumps with the probe mod I mentioned. Port mods put dangerously high to legal levels and wouldn't recommend much unless retaining stocked with long barrel as a rifle.
A friend has a 2240 with some mods and he swaps out for a longer 10.1mm barrel on cold mornings for about 4.5ftlbs. Probably enough for rats at 10 metres

[harvey_s]

Some time ago I did a review on here on exactly what you're asking about - see here http://www.airgunbbs.com/showthread....highlight=gmac

PS I also got considerably more power than Clarky claims above at temperatures just a few degrees above freezing.

[short-carabine]

Some time ago I did a review on here on exactly what you're asking about - see here http://www.airgunbbs.com/showthread....highlight=gmac

PS I also got considerably more power than Clarky claims above at temperatures just a few degrees above freezing.

Thanks for reposting that original thread- I wasn't sure if the hollow probe made that much difference, but it clearly does have an effect. I haven't experienced power losses in the order of 50% from normal on a colder day either.

[TonyL]

Except don't do it on really cold mornings. Your power will drop to about 3ftlbs with the gas bulb Crosmans....wouldn't be fair even on rats.
I found the 1377 unaffected by cold temperatures, comfortably hitting high 550s with most .177 8 grain pellets on 10 pumps with the probe mod I mentioned. Port mods put dangerously high to legal levels and wouldn't recommend much unless retaining stocked with long barrel as a rifle.
A friend has a 2240 with some mods and he swaps out for a longer 10.1mm barrel on cold mornings for about 4.5ftlbs. Probably enough for rats at 10 metres

Mmm....

I have two Crosman pistols, the 1377 and the 2240.
They both have pretty much the same mods.....The 1377 has a Crosman steel breech, standard length G-Mac brass probe, shoulder stock and 4x32 scope.
The Ratty has a G-Mac steel breech, the extended probe (not hollow) and the shoulder stock and 4x32 scope again.


Both used primarily for short-ish range informal target shooting at home.

I had thought about employing the Ratty as a short range ratter around sheds/barns, but the cold weather performance has always worried me a little, although I've not tested the drop off myself. In warm conditions, it's doing 5.7!

I was thinking of reverting it back to pure pistol and using just for fun, but then I read the above posts and think maybe I did ought to give it a try on short range rats. She certainly hits hard enough at 10 yards when warm.

On 10 pumps, the 1377 is doing 4.5ft.lbs. This is on standard valve/pump etc. sometimes I wonder about doing the flat top piston and valve conversion, but the think "why bother" as it's only for short range duty anyway, and I have plenty of full power rifles.

I haven't experimented with different ammo....I use Hobbies in both......That 1377 is INCREDIBLY accurate...I normally only use it on 6 pumps. As long as I put the effort in, this thing will shoot tiny, tiny groups at 10 yards, as in 1 to 2 mm centre to centre. Excellent performance, I think, considering the price...However, once the concentration, trigger control and follow through is not fully respected, it will shoot the odd flier. I put this down to the slippery butt, the heavy and creepy trigger and the fact that it's so light, it punishes any sloppy technique. Now I could re-work the trigger, fit a grippy butt pad etc., but, as I say, I have plenty of other much more serious guns, I don't deem it worthwhile for me at the moment. When you really get "in the zone" with it, it will keep dropping those Hobbies down the same 6mm hole.

The 2240. As it currently stands, the trigger is worse than the 1377. And there is also a noticeable "flip" on discharge....You certainly couldn't rest it on a hard surface.
Now, I can shoot groups at 10 yards which you can cover with a 1p piece. Then I might shoot a 1 inch group. Then, another group will be tight, but with a flyer an inch wild.
I refuse to blame the accuracy of the gun. Rather, I put it down to myself. But you really have to work for those tight groups. Could be barrel crown, could be pellet fussiness, but, because it will print those nice, tight groups, I prefer to blame myself!!
This is why I was thinking of reverting back to pistol format and using just for pure FUN, with either a MIM rear sight, or maybe red dot.

But then I read about close range rattiness and think I ought to keep it like it is!!!!!

Probably best to leave it as it is for the time being, then!!!!!