Ruger 77 Mk II trigger

I'm no metallurgist or machinist but the sear is a little bitty thing... I find it VERY hard to believe that one teeny little section of it is heat treated separately from the rest. I'd be fairly confident that it's all the same. The danger is in changing the angle, not so much in making the edge "soft".
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There are two different kinds of hardened parts. If it is like a S&W handgun hammer, it is "case hardened", which is a soft, low carbon part that has had carbon infused into the outside of the part (with a carbonaceous product like Kasinite), to a depth of only a few thousands of an inch. The second type is a high carbon part that, when heat treated, the whole part hardens all the way through.
Therefore, it depends on if the part has been case hardened or hardened all the way through, if removing a few thousands of the outer surface will end up causing a problem.
 
Second-hand info here, but I'm under the impression that the Ruger trigger parts are sintered or MIM parts and that they are surfaced hardened only. That means if you stone or file them you are exposing unhardened metal below and your great trigger will turn into an accidental discharge machine in only a few hundred pulls.

Again this is second hand, but it does explain why no gunsmith I've ever heard of is willing to stone/polish them and all recommend a replacement instead.
 
Sorry for this, I don't mean to hijack this thread, but Longdayjake's link shows a guy taking metal off of the sear? I was told by a master machinest and master gunsmith that you never, ever take metal off the sear as it is heat treated and the hardest part of the sear is right on the edge. By removing that you are creating a trigger that at some point is not going to operate correctly since it'll round off the edge. Thoughts?
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Since I'm a retired metallurgist this could be true if the part has been "nitrided". This is a very hard, very "shallow" heat treatment. If it has been carburized or induction hardened it would be much deeper and probably not an issue. It also might just be chrome plated which wouldn't be very deep also.

The master gunsmith and master machinist told you right! Here is approximate "depths" of hardness for different heat treatments FYI. These can be varied but these are more common... Surface hardness would be HRC60+ and the "depth" is where the hardness drops down to HRC 50. The heat treatment used depends also on the steel chemistry and material type (stainless steel, alloy steel, plain carbon steel, etc).

Carburizing - usually over .020" deep
Carbonitriding - around .015-.020" deep
Nitriding - typically around .010" deep
Ferritic Nitrocarburizing - .005" deep
Induction hardening - .020+

Not a heat treatment but chrome plating - .010+
 
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Well there you go! I knew there were some metallurgists around here!:D

Why the shallow heat treating? On some parts I can understand but it seems like on a trigger part it would be faster/easier/cheaper to just do the whole thing.
 
The shallower the lower the cost to heat treat and also some heat treatments are not capable of depth. Heat treatments are chosen based on the "load" on the parts so since there is hardly any load on trigger parts a shallower heat treatment will work just fine. A highly loaded, heavy duty transmission gear (for example) would be carburized to .060-.080 depth. And the base material chosen would have to yield a "core" hardness of around 30-40 HRC to support the case under load. Shallow nitrided cases are very hard and the harder the surface the less friction during movement. Barrels and receivers must be "tough" and still have some hardness so usually alloy steels (or alloyed stainless steels) are used that will harden to HRC 50ish and then are tempered down to HRC 32-40 throughout the whole part. This gives them good hardness without being brittle. If you hardened something through to HRC 60 it would be very strong but brittle. It couldn't take "shock" without shattering like glass. This is why parts are "case hardened" (hard wear surface over a tough core).
 
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http://www.shootersforum.com/gunsmithing/21068-ruger-77-mk2-trigger-adjustment.html

This is probably the most in-depth write-up I've found for a DIY trigger job on our mkii's. I haven't tried it yet but plan to this winter on a 22-250. I like the timney triggers I've put in three of my mkii's and would buy a timney again without hesitation. Modifying a factory trigger will be a good learning experience with the bottom line being that if I have any doubt whatsoever about the safety of the finished product, it will be scrapped and a timney installed. As for the exposure of softer metal & subsequent wearing of metal thereby creating a negligent discharge looking for a place to happen I can't say. I have stoned a 77/22 trigger in conjunction with a spring replacement which made an excellent trigger. I have over 2k rounds through that 22lr without any perceivable wear or otherwise negative results.
 
Wish I had known you were selling that magnum contour skeleton stock. I'm one of the weirdos that likes those stocks & I'd have taken it off your hands.
 
If you like the feel of your trigger and only want to lighten the pull, I would definitely start with just a Jard, Timney, or Wolff trigger spring.

Why mess with metal, when a spring could be all you need? ;)

If you do want to start messing with metal, I have stainless Mk II trigger here, that I could send your way for a reasonable price. (I went the Timney route, on my SS/Lam Sporter.)

Oh... I actually have the reduced power Timney spring here, too. I ended up putting the factory spring back in, with the Timeny trigger and sear. The sub-two-pound pull was too light for me.
So, if you need one or both of those parts, send a PM.
 
Why the shallow heat treating? On some parts I can understand but it seems like on a trigger part it would be faster/easier/cheaper to just do the whole thing.
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A case hardened part allows maximum hardness of the bearing surfaces, but if the whole part were that hard, it would be brittle. Case hardening produces a part that is not brittle, but still has contact surfaces that are very resistant to wear.
 
mdd,

I have a skeleton stock from a .30-06 MKII that I would be willing to get rid of. I don't know if that works for a magnum but if it does let me know if you are interested.

As for cutting springs, grinding on sears and other internal trigger parts..... you are "picking up pfennings on the Autobahn" there....... saving $50 bucks so you can stand a good chance of having a ND (and you modifying the trigger makes it Negligence) and losing everything you have and are ever going to have...... that is just ....... words fail me.
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I wouldn't have done anything to my rifle that I thought was the least bit dangerous. I have tested every possible way that the rifle might ND and I have been unable to get it to do so. You can call me crazy all you want but my guess is that you actually have no clue what went into doing it. If you could have watched what I did you would not think it was in the least bit dangerous. I did not go near as far as the guy went in the link I posted. All I did was lessen the tension on the spring (by cutting a little piece off) and polished the trigger and sear. If those are things that you think are dangerous then what do you do when your guns get a few thousand rounds through them and those parts get polished and the springs lose some tension?
 
Jake, dependent upon condition I'd be interested. I have a 270 that I bought off gunbroker that could use a better one. The guy selling it was very careful to not mention or show in pictures his bubba job on trying to install a front sling post. Idiot really did a number on it. Pm me some photos or an honest description of the wear & markings on the stock as well as a price.
Thanks!
 
.270 should drop right in Jake's .30-06 skeleton stock. I had a .300 Win Mag stock and I think the barrel contour is a little bigger..... :)
 
Yeah it is. I used to know the mold numbers for the short action and the two long actions but time has erased that info. 25-06 uses the magnum contour barrel though like what you had.
Short action skeletons are tough to find for any kind of reasonable price. I remember about ten years ago paying $50 each for them because nobody wanted them.
 
I ground down the sear on my m77 mark II and its one of the best triggers I have ever felt. No creep and pretty light.
I haven't had a problem yet. I hadn't even heard of surface hardening on ruger cast parts. I just thought they were pretty much uniform.
 
When I looked at my Ruger trigger while putting in the spring it did not appear to have been heat treated. If someone has put a hone to it they would have been able to tell for sure by how hard it was to remove or polish the metal. Should have been pretty time consuming if it was heat treated. Anyone comment on that? This is in regard to honing only, not grinding. You can readily grind something heat treated.
 
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