STI Sentry Trigger problem

[jerryz]

I have an STI sentry in 45 that I love. Works great.

The only thing that is weird is a quirk in the trigger.

It's an Inifnity triglide trigger with short flat insert and EGW hard sear.

What I notice is that if I press on the top of the trigger, it breaks light and crisp

But, if I press on the bottom, or even lower mid, the trigger pull goes up a lot.

I first noticed it when shooting a match, left handed only. I pressed and pressed and pressed and could not get it to break. I thought either the thumb safety was on, or, I was not on the grip safety. It turns out that, left handed, my trigger finger naturally goes to the bottom of the trigger (I had my finger cut off once and it's a little crooked).

Anyway, here's the question: I think I should swap out the flat trigger (which feels weird anyway) and get a curved. But, I can't quit get my directions straight on where the curve should be. I would assume at the top, but, I thought I'd ask before I buy.

And, I'd welcome any other advice.

Thanks

[shotgunone]

Sound more like a binding issue with the trigger. There shouldn't be that much difference in the trigger pull on a 1911 unless something isn't fit quite right. I'd take it back to the gun smith that put the SVI trigger in it. Even if you want a curved trigger I'd get it fixed before I swapped trigger shoes.

Edited May 13, 2015 by shotgunone

[zzt]

It may be the trigger shoe, not the insert is to short (height) and is allowing the trigger bow to ride up a tad when the trigger is pressed from the bottom. Since it is an STI with a MIM grip safety, make sure the arm isn't bent and that when the GS is fully depressed the arm completely clears the trigger track.

[2MoreChains]

I think ZZT is onto something here. Coat the arm of the grip safety with some dykem and then start pulling the trigger in different ways (middle, low, high) to see if you can induce the same kind of binding. Then check for wear marks in the dykem. If ZZT is correct, you will probably need to file a little off the underside of the arm. A few strokes with a file may be all that you need.

[jerryz]

This is a little above my technical gun smithing expertise, but, I think I understand your analysis.

I really appreciate the help.

Thanks

[2MoreChains]

If you end up takng your gun to a gunsmith, ask him about relieving the underside of the grip safety's arm so it engages even when not fully depressed. Most folks that use a high grip have a tendency to not depress the GS completely. "Tuning" the grip safety can help with this. I like to set mine up so that the GS is still functional (the arm prevents the trigger bow from going to the rear and tripping the sear) when the gun is not gripped. However once I grip it, it doesn't take much to engage it, which lifts the arm away from the trigger bow, clearing the path for the bow to go to the rear and fire.

[jerryz]

Ok. Good advice. Thanks!

[Sandbagger123]

take the grips off and look inside and see what you can see. i too think its the grip safety

[jerryz]

OK. I finally had time to look into this. I don't think it's the grip safety.

I have an Infinity Tri-Glide trigger. If I pinch the trigger between my fingers, I can twist it quite a bit up and down. It's like it pivots on the trigger bar. That is, when I press on the top of the trigger, the bottom moves out and vice versa.

None of my other .45's do this, but, none of my other 45s are anything but one piece stock triggers.

My guess is that something is loose / broken.

Ideas?

Thanks

[jerryz]

Found the problem. Or, at least, I found what I don't like. The trigger and trigger bow are separate pieces. This allows the trigger to rock up and down, depending on where you press on it. WIth a stop screw in the bottom, you can press on the bottom all day and it won't go bang. But, it will if you press on the top. During an event, esp if I don't get a perfect grip, this screws me up.

Even though the Infinity Tri Glide is supposed to make everyone tingly, is this broken or is this typical? If typical, what should I swap it out for?

stitriggerbar.mov

[zzt]

The SVI trigger is a delicate piece. It is very easy to loosen the shoe from the bow if not careful. You can try restaking it. Make sure you have everything aligned properly. Alternately, you could put a drop or two of Red Loctite on the stake, then insert into the pistol. Position the shoe so that the pistol will fire when pressed. Then just leave it alone for a day or so to make sure the Loctite sets. BTW, thoroughly clean the area before using the Loctite.

You have not eliminated the GS as one of the problems. You have also determined the trigger shoe (not the insert) on your trigger is too small. There should be very minimal vertical play, or horizontal play for that matter, in a properly fitted trigger. I'd start over with a new one

[jerryz]

I am pretty gifted mechanically, but, I have about zero craftsmanship skills. I will be swapping out triggers and trigger bars.

Any recommendations?

[zzt]

It depends on the shape of the shoe you want. I don't mind reprofiling, so the sky is the limit.

When I first started i believed a lot of the 1911 folklore. One of them was you had to have a very light trigger to avoid trigger bounce with a light pull. So I used Wilson's and other skeletonized triggers with Ti bows, etc. They were all delicate.

One day my Sig 1911 started dropping the hammer to half-cock when the slide dropped. The hammer hooks were a mess. They were recut to .018" and the sear nose had a True Radius put on it. I reassembnled and found I had a glass rod 2.25lb trigger pull that was 100% safe. The Sig had a "regular" trigger in it. I was just finishing a 1911 build at the time, so I decided to experiment to see if the Sig was a fluke.

I replaced the Wilson trigger with the Ti bow that I had already fit with an EGW unit. I picked the solid shoe version with the rear extension for over travel and the bow made on the original Videcki dies. I figured this was as heavy as you were likely to get (it is light BTW). I fitted it and adjusted the sear spring to get a 2.25lb pull. It passed all the safety checks, so I headed to the range. 100% reliable. Over the course of two weeks I fired about 400 rounds through- bullseye style, two handed, machine gun, etc. No problems at all. Another folklore myth busted.

So from then on I'm using triggers with robust bows. You'll have the trigger in and out of the gun 100 times while fitting the height and width, so it pays to have a sturdy bow. I like the EGW units. The shoe is double staked and red Loctited in, so it's rugged. It will require fitting. The one I fit into an STI forged receiver required an appreciable amount removed from the top and bottom of the shoe and almost nothing from the sides. You have the same receiver. I suspect that will be the case with most shoes. If you want to minimize the amount of fitting, start with a "drop in" piece. This Wilson should work. http://shopwilsoncombat.com/Competition-Match-Trigger-Long-Pad/productinfo/1/ I also like the Ed Brown and Harrison Design, but you will have to fit the height.

Edited May 26, 2015 by zzt