How much cocking piece-to-sear engagement?

C

CubCouper

Rodney Brown
I was installing a new trigger in a Bat 3 Lug rail gun and ran into a problem. The old trigger (a Jewell) was working fine, but when I installed the new BixnAndy, the sear height was off just enough that it would only just barely engage the cocking piece if the bolt were slowly and carefully closed. Just touching the bolt would release the firing pin. I tried the trigger in a different Bat and it worked fine. I tried it in this gun with 3 different hangers and had potential slam-fire issues with all of them..

Looked over the geometry and decided that I could fix the height issue by shaving a bit off the trigger hanger, raising the trigger in the slot. I had a spare 10-20, so I tested it by milling .013 off the top and contact surfaces to raise the trigger. It now works very well. Question is "what is a proper amount of engagement between the cocking piece and the sear?" I used a Sharpie mark to eyeball the Jewell engagement at .025 to .030" and the new trigger is now about 013-.015" .

Should it be milled a bit more? I can't seem find a specification or any kind of a rule-of-thumb to go by.

Rod
 
I think that you can come up with an answer for this by looking at how cocking pieces have polished the sears of your Jewel triggers. On my Jewel, which has spent most of its life on a Viper, it looks like the contact has been about half way up the angle of the sear. By measuring the height of that angled section, I think that you can come up with a suitable number. Initially, when I got the action, The cocking piece was lightly making contact along the bottom of the groove in the bottom of the bolt raceway, so I carefully shortened it until that contact was eliminated. Mine was an early action, and the cocking piece was from Remington ( I believe) and so the dimensional issue undoubtedly was because of their production tolerances.
 
Looking at the Jewell trigger shows a well polished edge that probably isn't more than .025". I went for about half that on my first modification of the trigger hanger.

Most discussions I see on sear engagement are discussing the trigger lever to sear end of the equation, but I can't seem to find any specs on the sear-to-cocking piece end. I would call this trigger height since it is adjusted by changing the relationship between the trigger pins and the receiver to raise the sear into the bottom of the action. Clearly it has to have enough engagement still hold against any slop in the bolt-to-receiver and is limited by the amount the sear drops away from the cocking piece (maybe .090" on a Jewell?). Just wondering if anyone knows of an 'official spec" for safety or for accuracy concerns.
 
BAT isn't the only one having to make new hangers for the Bix and Andy. I had to get some hangers from Jim to install in a Borden BR this week.
Makes me wonder how well they will work in a action with a pinned trigger.
 
They fit perfect in a remington. I have 2 in 40x actions and one in a hall. The aluminum side plates are not milled low enuf for a hanger except my hall.
 
Honey may I??? I wouldn't let that get started she will think it's supposed to be that way.
I "used" to tell mine where I was going as I walked out the door, jus so she wouldn't wonder why I left.
 
Whoa Pete! That sounds an awful lot like castration. No friggen way!
I'm just really into the idea of never getting married again. Marriage is something I never thought I'd do but if your going to do it, do it once and make it last a lifetime.
I got lucky... mine left! I have a lifetime of reasons to make it the only marriage I will ever have. Been a bachelor 13 years and it gets better every year.
 
You must log in or register to reply here.
Back
Top