UPGRADE SCREW KITS
All of these kits fit models with (or upgraded to) a steel breech. They are alloy steel hex-socket drive with black oxide finish. Some of these screws and washers are difficult to find sizes. These are the most precise-fitting screw kits available anywhere. Upgrade inner breech screws and valve screws are not included but are listed separately. Hex wrenches are listed separately. Driver sizes for these screws are listed below.
The PISTOL KITS include two grip-screw head diameters. The larger heads fit Crosman 1399 stocks and some grips. Smaller heads are required for other grips. I machine the heads to the smaller diameter, these are shown in the last photo.
The 13XX KITS fit with or without a Magnum Adjuster. They include a 1/4" rear trigger-frame screw and spacer washers for the rear breech screw. Two rear breech screw lengths are included. One is standard 3/4" to fit a standard steel breech and tube plug. The other is 11/16" for mounting a Magnum Adjuster. The longer screw will also fit with the Magnum Adjuster if you use both included washers but the head may stick up high enough to interfere with mounting rear sights or scope rings. The shorter screw requires one washer to fit with a Magnum Adjuster and won't interfere with sights or rings. If not using a Magnum Adjuster the 3/4" screw should be used with no washers.
Forearm screws for the 1300KT, P1377 and P1322 are included, these will not be needed for models that use pins to mount the forearm.
The kit in the sixth photo includes only the 11/16" and 1/4" hex-socket screws with one washer originally included with the 13XX Magnum Adjusters.
The DISCOVERY / 2260 KIT includes a 3/8" rear trigger frame screw to fit with a Magnum Adjuster but fits without the adjuster also. Two stock-screw lengths are included, one is 5/8" and the other 3/4". The original length is 5/8" but some fit the 3/4" screw better. You should be able to thread it in 3-4 full turns without forcing it. It will bottom-out in the stock-lug at 5.5 turns so use a length that holds the stock firmly with less than 5 turns.
The MAXIMUS KIT includes a 3/8" rear trigger frame screw to fit with a Magnum Adjuster but fits without the adjuster also. A 1" stock-screw is included for the original plastic stock. If using a Discovery hardwood stock a different screw length is required, you should get the Discovery / 2260 kit instead. That stock-screw length is the only difference between the two kits.
HEX SOCKET SIZES:
1/16 trigger frame cover screws
5/64 grip, 1399 stock, 13XX & 22XX forearm and set screws
3/32 rear breech and trigger frame screws
5/32 Discovery, Maximus & 2260 stock screw