If anyone is interested, here's the approach I've used a few times.
This article is about the basic Crosman trigger present in the Discovery & Maximus, 2240, 2400KT, 1377 & 1322, etc. I know there's a lot out there on how to improve it, including some very creative use of bearings, modifying the parts to get more mechanical advantage, and so forth. But here's my modest approach on making it better. Bear in mind no amount of work to a direct sear trigger is going to match a decent drop sear. If you want that, do the Marauder retrofit and don't look back. But if you find it hard to drop that kind of coin on a new trigger group, please read on.
So what all does this tuneup involve? Four things:
- smoothing and polishing - the basis for most every trigger tune
- reducing the pull weight - a lighter spring combined with #1 makes this possible
- eliminating the sideways slop in the trigger blade - a mildly annoying thing that makes a trigger feel cheap
- eliminating the sear spring's interference with the housing - this is a key source of annoying stick-slip-stick-slip behavior. Doesn't affect all guns but seemingly most.
Okay so let's jump in. First order of business is to deal with that Mickey Mouse sear. Oh my, it's a piece of
shi stamped steel that looks like it was cut out by an angry beaver. Pictures are better than words so I'll let these be the guide.
To understand a little better about what we're dealing with, the following graphic shows the type of edge produced by a shearing operation. If you look closely at your sear as it is delivered from the factory, you can make out the shiny
burnished portion and the dull
fractured portion. You can also feel the slightly radiused
rollover on the top side and a sharp
burr on the bottom side. Our aim is to get rid of all these things.
Besides the obvious flattening and polishing visible in the photos, I recommend also taking a few angled passes to remove the burr on the tearout side. If all our parts remain perfectly orthogonal, the burr is irrelevant. But there is some play in the parts and they will twist on the pivot pins which gives some opportunity for the burr to introduce friction so I like to go ahead and knock it down.
For best results, I also recommend smoothing the hammer. I had already done that to mine some time ago and I didn't want to remove the breech and barrel to pull it out for a photo.
For the trigger, smooth and polish the rounded face that presses against the sear:
Now with all the contact points smoothed, you may still feel some hitches in the pull...the stick-slip-stick-slip thing I referred to earlier. If you don't, you can skip this part. If you do, it's easy to chalk it up to whatever friction remains in the system but that may not be the actual cause. Take a close look at the spring while you pull the trigger. The coils tend to drag on the sides of the trigger frame. There's a beveled edge that keeps it from snagging hard but the interference is enough to be easily felt.
So to address that, I made a little guide block as shown. It fits into the rectangular channel underneath the sear and is just tall enough to keep the spring out of the trigger frame so it can't catch on anything. This one was done with hand tools so don't let that stand in your way.
But then a few days later I realized what I had made was a Lego block. Turns out these work beautifully:
On with final assembly:
Start by doing a dry fit to make sure everything goes together okay. Use this step to determine if your spacer washers are right to take up the side play but not so thick as to cause things to bind up. Similarly, check that the guide block moves freely when you exercise the trigger. Once you're happy with it, lubricate the contact surfaces and do a final assembly.
The resulting trigger pull should be much smoother now and between 8 - 16oz depending on the strength of your hammer spring.
I hope this helps!
