The second stage trigger pull on my No. 4T was just over 5 lbs.  Too high for Vintage Sniper Match shooting with rules that allow a minimum of 2.5 lbs. Had been meaning to do this for a while. 

I typically set the triggers on my No. 4 rifles to about 4 lbs for the 2nd stage.  But I once failed a rifle inspection on my primary No. 4 shooter, our CMP Rules for Vintage Military Rifle (bolt action) allow a 3.5 lb min trigger pull. This is for the Service Rifle category, not Sniper which is 2.5 lbs. 

I’ve also had the experience of working the cocking piece bent angle too steep one time and loosing the feeling of the 1st stage entirely with about a 2 lb second stage pull. Then had to start all over.

So, for the T, I decided to target 4 lbs, a healthy margin over the 2.5 lb minimum.  I do this by holding the cocking piece in a small vice such that the sear surface protrudes from the vice jaws by about 1/16 inch.  Adjust the angle of the cocking piece in the vice such that the stone sits on the top of the jaws at one end and on the bent face on the other end to get the desired angle on the bent. It’s a bit of a trial and error process.  

I actually don’t use a stone, I use diamond files in three different grits, Medium, Fine and X-Fine. The X-Fine file leaves a polished surface. I tape the top of the vice jaws and wrap a few turns of tape around the front of the file/stone and apply a little petroleum jelly to the tape so the jaws don’t get filed down and tape easily slides.  Works really well and lets you hold the file/stone flat keeping the bent surface flat and square. 

This took me two attempts.  The first attempt did not seem to change the pull weight at all, even though it increased the angle of the bent by about 1 degree.  Second attempt brought it to 4 lbs 1 oz.  Decided to stop there and shoot it for a while, it may bed in a bit more. 

I also wonder what practical minimums this type of trigger can be worked down to. You really want the trigger to return to stage “zero” as Shamu call it if you release the trigger from either the Stage 1 or Stage two position.  On that 2 lb trigger I did, it would not return to stage 0 when released, it remained in its position which is a dangerous condition.  

And you need to measure trigger pull weight with the magazine inserted, this increases tension on the sear spring. 

First photo shows cocking piece in vice with surface of bent just above the jaws of the vice.

Second photo shows position of stone or diamond grit file.  I make small strokes of the file, no more than an inch, so that the bent surface does not get rounded.  

I checked two NOS cocking pieces I have, and both are 94 degrees. I should have measured the one I just worked off the No. 4T, but suspect it’s around 97 deg. 

One thing to be careful about.

Those surfaces are case-hardened, don't break through that or you'll just create a "furrow"

This is one part that I find does wear after a lot of use. I’ve had to dress up a few cocking pieces because of wear. But that was after thousands of rounds, perhaps 5,000. 

Regarding the angle; The L39 A1's were modified for Target shooting; so went from 94° to 100°.

I have modified my other rifles to around 96°.  This gives a decent trigger pull without any safety risks.

The risk of removing too much material; can cause a potentially dangerous situation!

When pulling the trigger to first stage; the cocking piece slides rearwards slightly as the sear approaches the edge of the cocking piece face for second stage release. 

If you pull first stage, then decide NOT to take the shot; it is essential that the cocking piece returns to the fully forward position. If it stays in the rearwards position, it can release the shot accidentally if the rifles gets a knock!

For the rig; I used two wooden blocks; one for the Arkansas stone. The second has a slot for the Cocking piece. it is a snug fit. There is a small screw at the lower end of the channel; to adjust angle of the CP. It's quite a slow method, but it is accurate. 

Addressing trigger pull is a fairly important step towards shooting these rifles competitively.

One place I use grease is on the front face of the cocking piece.

Just a tiny dab. But I've never worn one in all the time I've been shooting. It also smooths the feel of the trigger a bit.