Diana Mod.25 direct sear trigger - any way to improve the extremely heavy pull?

[Toxylon]

I have a Diana Mod.25 from the early 60's. It is pretty worn, looks-wise, so not that high in value, and I don't have the incentive to collect antique guns for the sake of it, anyway. I want to shoot everything I own.

After getting the gun, I opened her up, replaced the extremely worn spring, re-oiled the original leather piston seal and lubed the whole thing. It's a nifty little gun with pretty good zip and potential for accuracy.

The only serious issue with the gun is the super-simple, direct sear trigger, that has an unbelievably hard pull. Like: after getting the sights lined up, I have to pull the trigger so hard that my sight picture cannot stay put, and I'm a pretty buff guy.

I'd like to introduce my kids to airgun shooting using the Mod. 25. It has such a little Junior style stock it fits them well, and is easy enough to cock and hold. It'd be a blast to let this gun do the thing it did already almost 60 years ago. I just don't see it happening with the (I'm guessing 8#) trigger pull.

Is there any safe and simple way to decrease the trigger pull on the Mod.25? The direct sear trigger is of such primitive design I'm not sure cautious smoothing etc. does much, but I have done zero trigger mods to date. Of course, especially with kids involved, there must be zero issues with safety.

I know the more sought-after Mod.25s had excellent three-ball triggers. I haven't found a source for these (and even the direct sear trigger is 'obsolete and unavailable' at Chambers). I don't even know if one would be a drop-in replacement for this simpler variant.

[AGEnthused2]

I have used moly grease on direct sears before, a very tiny amount of it, I had to remove some of the grease because of how slick the trigger became.
I was using something with about 70% molybdenum powder in it.

[larspawn]

I don't recall either of my M25s being heavy triggered at all.  I'm gonna go down and shoot them again to confirm but pretty positive they are not heavy at all.  Maybe you're overspringed?

[larspawn]

Just went down and shot my early 60s M25.   Single stage, crisp let off but not heavy at all.  I also shot my Winchester 425 dob 11/68.  It has two screws in trigger for adjustment so thinking it is the three ball trigger.  Very nice trigger.  Slightly lower pull than the earlier M25 but it has a nice smooth "first stage" and a very predictable and light trip.  I never really noticed how nice that trigger has been adjusted!

[Toxylon]

Thanks guys!

I shouldn't be overspringed, as my replacement spring is a Mod. 25 spring from Chambers, and it's a lightweight to cock, as is the original. The spring is still new, but when I shot a couple of feeler shots with the old, spent spring, the trigger pull was weirdly high there, too. I'm not sure if it's much higher now or not. I didn't try to hit anything with the old spring still in place, and the heavy pull only became a serious issue when actually aiming the gun, not just testing the operation.

Good to hear your M25s have reasonable pulls. I was thinking that Diana would not have produced this kind of trigger, even 60 years ago, and on a budget model. Mine clearly has some issue, even if the trigger is ultra-simple. I'll look into lubing the sears first. That's the one place I didn't put any lubrication on. Will report here. Keep suggestions coming!

[dtdtdtdt]

Could be damage to the sear and let off bevels. Very gentle polishing with extremely hard and smooth stone might help.  Just be careful to analyze where you need to polish.  I have never seen that gun or its trigger mechanism so am guessing. 

Examine them under a magnifier to look for burrs or damage.

[HectorMedina]

Ilimakko;

I would advise, first of all  to download and print this:

https://www.diana-airguns.de/fileadmin/Editoren/PDF-Downloads/Download-Techische-Info/Ersatzteillisten-Luftgewehre/Modell_25.pdf

Now, as to the trigger:
Part 18/2 is the critical part.
IMHO, MOST PROBABLY, it is "rusted or crusted" (old grease, or dust and oil cake).

Start with a good cleaning/degreasing (use lacquer thinner, or even acetone if it needs to), and the make sure it IS clean. DO the same with the piston stem's groove.
Put a small droplet of good gun oil in your pinky finger, then rub the pinky to the thumb and then rubbed against your index will put the right amount of oil on the index. Work your touch into all the surfaces and test.
IF it is still too hard (on these guns a 3# trigger would be the upper limit), then  do as DT says and get some black hard Arkansas honing stones/polishing slivers (about 1000 grit), and very carefully, KEEPING THE ANGLES, polish (as in don't erode the hardened surface of the case hardened part) the faces of the sear and the piston stem.

If the faces have been damaged, then you have a wall hanger unless you locate another 25 that is beaten up and can be a "donor" gun for part 18/2:
https://www.egun.de/market/item.php?id=8760020

OR you can try to replicate the part in D7 tool steel and then either case harden, or tempering and drawing the steel.

They are nice, small guns, and they are plentiful, so they are not collector's items.

You can get good shooting 25's between €40 and €80, depending on condition, but it is only worthwhile if the gun in question has some sentimental value:
https://www.egun.de/market/item.php?id=8751096
https://www.egun.de/market/item.php?id=8708096

I am almost positive that a good cleaning and a good lube will restore the gun to usefulness.

IF NOT, do consider the Mod "Eleven" as a viable alternative to teach your kids how to shoot.

Keep us posted, keep well and shoot straight!






HM

[Toxylon]

OK, so: I took the 25 apart again and lubed the trigger and the piston stem sears. No burrs there, more like well-rounded edges, indicating heavy use in this oldie's past. Put the gun back together and went to the range.

A little moly had done wonders: gone was the ridiculously heavy pull. Instead, the gun would go off a little too easy. More accurately, the trigger pull varied from a nice couple of pounds to touch-and-go.

After some 20 shots the gun would not re-cock, the sears simply slipping apart. Clearly the action had had too much of a good thing. So, I took the trigger out and wiped its sear clean. I didn't degrease it, since some lube was clearly and badly needed. I haven't had a chance to shoot the gun yet. By cocking the gun and pulling the trigger while holding the barrel tightly, I can tell that a) the gun does not go off by itself, and b) the trigger pull feels appropriate.

I did the above after reading Dave's but before reading Hector's reply. We'll see how the gun behaves, and if further action is needed. For that, I'll have a bunch of good info. Thanks, guys!

[AGEnthused2]

Moly is some slick stuff, even when I try to go sparingly I still end up removing excess.
Apparently the molybdenum actually bonds with the metal, so you aren’t going to get all of it off.

[Toxylon]

Derek,

It was your input on lubing the sears that I went with, so far so good. If some moly bonds with the sears, it's fine by me, since the gun was close to unshootable without some.

[Yogi]

OK, so: I took the 25 apart again and lubed the trigger and the piston stem sears. No burrs there, more like well-rounded edges, indicating heavy use in this oldie's past. Put the gun back together and went to the range.

A little moly had done wonders: gone was the ridiculously heavy pull. Instead, the gun would go off a little too easy. More accurately, the trigger pull varied from a nice couple of pounds to touch-and-go.

After some 20 shots the gun would not re-cock, the sears simply slipping apart. Clearly the action had had too much of a good thing. So, I took the trigger out and wiped its sear clean. I didn't degrease it, since some lube was clearly and badly needed. I haven't had a chance to shoot the gun yet. By cocking the gun and pulling the trigger while holding the barrel tightly, I can tell that a) the gun does not go off by itself, and b) the trigger pull feels appropriate.

I did the above after reading Dave's but before reading Hector's reply. We'll see how the gun behaves, and if further action is needed. For that, I'll have a bunch of good info. Thanks, guys!

Were there any "crusty" bits?  Piston stem or sear faces?

-Y

[AGEnthused2]

Derek,

It was your input on lubing the sears that I went with, so far so good. If some moly bonds with the sears, it's fine by me, since the gun was close to unshootable without some.

I’ve had the most success with my Norica Dragon GRS, aweful trigger without the moly. Dangerously light trigger without removing as much moly as possible, I’ve rubbed q-tips over the greased area and tested until I feel safe. Mine took time but I feel like the rifle can be bumped and maybe dropped without firing, no more firing upon closing.

[dtdtdtdt]

I suggest that you start with Hector's methods first!  Because you put moly on them you need to get as much off as you can. Take the bits apart and soak them in an aggressive solvent like acetone, or perhaps Powder gun solvent - like Hoppes #9 followed by vigorous degreasing  and scrubbing the parts with an old toothbrush or bore brush.  Reassemble and test.  There may still be enough moly to do the job!  If not try Hector's lubrication technique. A little dab of lubricant is all you need. 

If the sears are rounded over too much you might have a wall hanger. I that doesn't lead to a result you like some honing with very fine stones is in order.  Unfortunately the very fine stones of appropriate shapes are rare and EXPENSIVE.  I paid over $100 for a set of such hones!!! Hard to justify for an old-timer gun with a one-off problem!!

Sears and grease don't go well together and can lead to unsafe arms.

A story I read about the early days of WWI.  The Russian Crown had an American company building 1891 Mosin-Nagants.  The inspector, a colonel from the Russian Army, had a habit of testing the trigger safety by cocking the rifle and slamming its butt against the concrete floor.  If the gun snapped its trigger he wouldn't pass the gun.  The company representative got tired of this behavior and had one fixed with a "norma" trigger.  He gave the Russian a loaded rifle to test. The Russian slammed the rifle down and the rifle went off.  According to the story, he never did It that way again...   

[h2rider]

You mentioned that the trigger got very light after lubing the sears.  I had a Haenel Model 1 with the same issue; the problem turned out to be a worn-out trigger spring.  No surprise since the Model 1 is over 80 years old.

With some of these direct sear rifles, if there is no trigger spring the sear will not hold; the setup may depend on a certain amount of tension from the spring.

I ended up ordering some 5mm diameter, 50mm long springs from China and got 40 instead of 4, so I have lots of extras.  If they would fit and you want me to send you a couple, PM me with your address.

Chambers in England carries the trigger spring for the direct-sear 25, but it will cost you around $10 with shipping.

Paul in Liberty County

[Toxylon]

A big thanks to all who replied above, and a quick update:

After wiping the trigger sear clean and putting the Diana together I took the gun for a spin. No slipping of the sears whatsoever, so good. Still, the trigger behavior of the gun changed again within 30 shots: in the first shots, the trigger pull was appropriate in terms of resistance, but curiously long. Then, the pull got shorter and shorter, as well as lighter and lighter. The last shots went off with the slightest pressure on the trigger.

I don't have the time to re-open and trigger tune the gun again for now, so I'll be taking an old, tame Cometa 400 to teach my kids shooting basics. It's not a junior gun, but still the lightest airgun I have, after the tiny Mod. 25, and I have big kids for their age.