Breech screw

[Adam77K]

Out if interest, would you say that most of the occurrences of stripping the breech screw are due to

1. Using an ill fitting allen key
2. Using too much torque
3. Not inserting the key fully, or
4. Repeated usage, i.e unscrewing and screwing back many times?

I ask because so far I haven't had any problems. I'm very careful, especially so given the warnings in this and other forums. In fact I'm probably over cautious.  I always squeeze the breech and tube together to reduce torque needed, for example.  That covers 2 and 3, and the key I've got came with the GMAC breech kit so is presumably the correct one and it does seem to fit well, so I think I've got the first three covered.

So my only concern really is 4.  Despite using the correct key and taking care, could it eventually strip regardless? I'd guess it is designed not for repeated dismantling and reassembly.

In which case I may change to the slot head which I already have standing by.

[Cross Pistol Packer]

Slot head the way to go,through like yourself I have been carefull with that 50thou key

[BDS]

and... 5) the screw and socket-head key don't have matching hardness, so the key usually wins 

Go with a slot-head or Torx if you can find one.

[T191032]

"1. Using an ill fitting allen key
2. Using too much torque
3. Not inserting the key fully, or
4. Repeated usage, i.e unscrewing and screwing back many times?"

For some, I'd say that "2. Using too much torque" may be it.  Crosman should come up with a better solution, but since they won't, the aftermarket modders did/do.

[ped]

the only one i've stripped was my own fault for not undoing the rear screw first and using a ball end allen key(biggest mistake)
i use both the original ones and the ones from gary(droid)
ped

[rangerfredbob]

Having not had an issue myself, I'm guessing user or tool error, I still say the T5 torx is probably the best method, I despise slotted screws in most circumstances...

[bgmcgee]

I would say all the above and besides Crosman using Chinese screws. 

[OrbeaRider70]

I say #4 and hammer fisting everything!  That said I replace a customers now when I tune their pistol with a stainless slotted version!

I learned my lesson with those soft screw heads and tiny little tiny head openings!!!!

[Flex]

Out if interest, would you say that most of the occurrences of stripping the breech screw are due to

1. Using an ill fitting allen key
2. Using too much torque
3. Not inserting the key fully, or
4. Repeated usage, i.e unscrewing and screwing back many times?

I ask because so far I haven't had any problems. I'm very careful, especially so given the warnings in this and other forums. In fact I'm probably over cautious.  I always squeeze the breech and tube together to reduce torque needed, for example.  That covers 2 and 3, and the key I've got came with the GMAC breech kit so is presumably the correct one and it does seem to fit well, so I think I've got the first three covered.

So my only concern really is 4.  Despite using the correct key and taking care, could it eventually strip regardless? I'd guess it is designed not for repeated dismantling and reassembly.

In which case I may change to the slot head which I already have standing by.

I have replaced the stock plastic breech on 4 of my Crosman airguns and have yet to have an issue. I did have the benefit of reading many of the threads and posts of those that DID have issues.
RE: the 4 possible culprits listed by the OP,

1. Using an ill fitting Allen key -- I used the hex wrench that I received with the steel breech kit.
3. Not inserting the key fully -- I think this is important ALL of the time! not just with Crosman products.
2. Using too much torque -- I try to use the shorter lever arm whenever possible.
4. Repeated usage, i.e unscrewing and screwing back many times Every time you take something apart and reassemble it, you run the risk of damage i.e. cross-threading, stripped heads, broken screws or worse yet lost pieces!

Additionally, (it was mentioned in one of the replies and I think it's important)  the rear most breech screw should be removed 1st then remove the front screw. When reassembling, the front screw goes in first and the rear screw last.

Also when reassembling, I turn any screw counter-clockwise until I feel the "click" of the screw thread engaging the thread of the hole.

I agree with those that think that the 4-48 screw with the 0.050" hex head supplied/used by Crosman is lame. If and when I do have an issue with this screw, I'll probably go with a Torx head upgrade. Flex