Rolling Triggers

[diehli]

This article linked from the November Brownell's WebBench has some great diagrams of the sear/hammer relationship and how to cut conventional angles.

http://www.brownells.com/aspx/NS/GunTech/N...x?p=0&t=1&i=545

Can anyone describe the engagement surfaces of a rolling trigger with the assistance of these diagrams? Particularly Figure 9, which shows how a conventionally-cut sear and hammer mate. How would Fig. 9 look if we were looking at a rolling break instead of a crisp break?

I'm getting it done on Saturday.

I asked Mike to explain it to me and it's basically what was stated in an earlier post. The sear's engagement surface is radiused off the sear pivot pin hole. When done right it neither cocks nor decocks the hammer during the pull. It other words, it's rounded, not straight.

[InTheBlack]

Geez, who really needs ounce-weight trigger pulls?

The Bullseye folks are using roll triggers with their required 4 1/2 lb pull weight.

[CEM45]

Is a rolling trigger when there is very little secondary angle cut into the sear?

How long does this setup last compared to the standard crisp trigger?

James

ROLLING TRIGGER? WOW I THOUGHT THAT WAS A HAWAII ONLY THING...

Lots and lots of gunsmiths out there, more that one way to do a "rolling trigger". The way I do them depends on how everything (hammer, sear. and frame holes/pins) match. Yes I use very little secondary angle.

Most rolling trigger jobs should last longer than the crisp ones, because most "rolling triggers" are very light (from 12oz to 22oz).

[Anthony Lombardo]

To achieve a durable rolling trigger that will work well down to 2 lbs, I match the sear angle to the hammer being used. CMC/Wilson have different hook geometry than Colt for example.

I use a brownells hammer squaring file to make sure the hooks are square, sharp and finish up with a white ceramic stone. I go no lower than .020". Hook heights are rarely even on factory parts.

I use an excellent AL Marvel sear jig (available at brownells) and have 3 different angles that I use that perfectly mate with the brand hammer selected. The jig needs to be adjustable unless you are content working with just one brand of hammer.

I cut a large primary angle and finish with a white ceramic stone using a blue sharpie the whole time to make sure my cut is even across the sear face-most factory sears are NOT straight and need the attention of a jig.

I then cut a tiny seconday angle-just enough to break the sears edge and then polish the hammer hooks and sear angles with simichrome on a felt bob to a mirror finish. This is critical. These parts should be well polished or you will feel every imperfection at lower trigger weights.

Then come the markers (Blue sharpie) to make sure I have even engagement. Keep in mind that you may have to slightly lower one side of the sear face to evenly match up with the hooks if your pin holes are not straight.

If the pull is too creepy, I remove a little more off the secondary angle, but usually it is fine.

I would suggest buying CMC/Kimber MIM hammers to practice on as they are hard as Hades and are inexpensive.

[Radical Precision Designs]

Many years ago, Colt came up with that "answer" for bulls-eye shooting. They called it the "Gold-Cup" sear system. The system included a specially cut and shaped sear with a slight notch in the center (for the the half cock hammer hook) and used a "spring loaded sear assist lever" drilled and positioned within. The hammer had a slightly different geometry, and differed from others in having the surface that normally would contact the actual hammer hooks/sear removed from the half cock notch. Very well thought out to eliminate any interference in hammer/sear "burnishing" and forming a lasting "mated",(protected) surface. That was the actual "official" beginning of the rolling(?) sear. A few smiths (including myself) of those early days (late 60's, 70's, 80's...) would avail ourselves of the Gold Cup sear and adapt the available "commander" hammers to work with them. Many would just mate the sear and hooks. I always also cut-off/relieved the sides of the halfcock notch, mimicking the Gold Cup hammer to accomplish a longer lasting sear surface, and still do it to this day. There was/were no other good sears to be used better than the Gold Cup, although the "assister spring hole" would weaken them somewhat to continuos pounding from heavy loads of "non bulls-eye loads". They (Gold Cup sears) were also much more expensive. But a few top pistolsmiths would consistently use them (without the sear assister and spring) for their top of the line guns. You can still purchase these sears from Colt, and with a little fidgeting put them to good use, but there are other available sears set-up along the same lines. Mostly by a few savvy 'smiths that still deliver the "goods" SAFELY, especially with a "full weight" mainspring instead of the "bulls-eye" (intended for) light 15 (or less) lbs. variety.

Perfect matching/mating of the the primary angle and a continuous "rolling"secondary angle of the correct proportion and relationship is what will give you that "snappy/crisp", yet rolling feel that lasts, and lasts, and lasts... but seldom (if ever) will be achieved by just dropping in "store bought" parts.

Edited April 2, 2006 by Radical Precision Designs