View Full Version : AR-15 trigger mod
February 12, 2011, 11:27 PM
Have any of you heard of installing a set-screw through the pistol grip screw hole to take up some travel? This is done with the safety on and only elimnates that bit of travel? I ask because I read about this in a follow up of the "15 minute job" at the Olympia Arms public forum: http://www.oa2.org/forums/viewtopic.php?t=10603.
I have a S&W 15-22 rifle with a slightly modified FCG. J-P spring set and some light polishing of the sear area. No removal of metal or messing with the sear geometry at all. It's smoothed out nicely but i was wondering about the above mentioned tweak. I do not want an un-safe gun, period. If it's wrong,it's wrong and no argument from me.:)
February 13, 2011, 02:19 AM
I've done it on a couple of .223 lowers, it does help somewhat when using the standard mil-spec trigger. IMO the mod shouldn't make the rifle any less safe unless the hammer can drop with the safety on before the mod, or if you adjust it so far the safety is unable to engage. I'm not sure however if the trigger mechanics are exactly the same in a 15-22, and in either case I would not suggest it if you've already changed to a lighter spring or otherwise altered the original configuration.
February 13, 2011, 07:40 AM
The pistol grip screw hole mod well eliminate some of the creep. If you over do it you may have a problem with the trigger reset. It's a worth while mod. There is no mil-spec AR15 trigger. These are semi auto versions of the mil-spec and some what different.
You can find the RRA two stage on arfcom for $80. A fluff and buff, set of springs, it makes a nice trigger.
Check out netflix.com for the AR trigger job vids. They have a couple of different ones, AGI is a good one.
February 13, 2011, 08:49 AM
There's a few lowers with it built in. I have a Superior Arms lower with that screw. I've never bothered with it. It might be worthwhile for a target or varmint AR, for a defensive carbine I'm not sure it's worth the trouble.
February 13, 2011, 03:57 PM
The screw-through-the-grip-screw modification became popular in the early 1980s as a way to control trigger nose to hammer notch engagement. That modification, along with careful selection of trigger and hammer, was the way to perform a "trigger job" before the proliferation of specialty trigger groups found in today's marketplace.
February 13, 2011, 06:48 PM
I appreciate your input. I was told on another forum that it was a non-starter as there is no take up in a stock trigger. The 15-22 uses a similar FCG as the AR if I read it right. I put in the set-screw on mine and just took up the slack with the safety on then backed it off a bit so that the safety is free to rotate. Using snap caps I dry fired the guns over and over then checked the hammer with the safety engaged and could not get it to release.
I'm going to try some live fire but I'll start off with one round in the mag and work my way up. One hiccup and we're done.
February 13, 2011, 10:24 PM
I bought an AGP lower with the set screw and it works. Properly adjusted, it takes 80% of the creep out, and that means 80% of the gritty milspec trigger is cleaned up without any stoning. Not stoning the trigger means not cutting through the hard facing and having it fail in a few thousand rounds.
It also means it has exactly the same kind of set screw adjustability that ALL the $150+ triggers have. Travel limiting screws are a common feature shared by almost all good triggers, including a lot of factory bolt actions.
Nothing wrong with the set screw, what's wrong is setting them up to have no clearance and a hair trigger spring load to boot. It's a target gun practice meant for controlled range or bench rest use, and not a good choice on duty or field guns.
Do the proper function checks, set it up properly, it should work just fine. Certainly a lot safer than a kitchen table grind job with internet video as a guideline.
February 13, 2011, 10:48 PM
February 14, 2011, 12:10 PM
It's not a 15 minute job if you lower isn't threaded all the way through the pistol grip screw hole. A hand reamer is your friend. :D
My RR lower wasn't threaded through, but my Doublestar lower was.
One thing that can be a problem: if your trigger group has a LOT of first stage takeup due to a long,long,long sear engagement, the rear of the trigger can be raised so high up that it hits the selector/safety when it is in the "fire" position, preventing discharge of the weapon or making movement of the selector stiff. I had to remove some metal on the upper portion of the back end of my trigger to allow proper function. If you have to do this, be SURE that the safety will still block the trigger properly when the selector is on "safe". Too much removal and the weapon will fire when on "safe".
This mod also increases the disconnector engagement of the hammer spur which makes trigger reset seem a bit more forceful or clunky. If you have a good trigger to start with, you may not even notice this.
February 14, 2011, 05:37 PM
I see no point in this. The good RRA trigger can be bought for less than $100 and installed in 5 minutes.
Then you have a good reliable safe trigger that will last a lifetime.
February 14, 2011, 11:35 PM
I'm in the market for a new trigger to replace the stock one on my
DPMS pattern .308.
A search of older threads revealed that AR 15 triggers will work on .308s.
Just need to get the correct pin size.
The thread also mentioned the sub-$100 Rock River triggers.
Can someone show me the way to that particular one?
A quick search of their site showed triggers in the almost $200 range.
That brings it close to a Timney.
February 14, 2011, 11:40 PM
RRA two stage triggers 3 in stock for $98.95 each (http://westernsportonline.com/index.php?main_page=product_info&products_id=85&zenid=92jnm0qglje2c84futc0cq89a0)
February 15, 2011, 08:25 AM
I agree the screw can be adjusted far enough the safety will hit the trigger bar.
You Don't Have To Do That, but some have to take out the last little bit of creep. On a dedicated range gun, it has it's place. That's usually a controlled environment.
I understand some don't appreciate home grown trigger jobs, but the fact remains, ALL the better triggers use the set screw to adjust travel, even factory bolt guns. Buying one of them and installing it isn't any different in operation, except it will cost you at least $100 more for the exact same benefit one 40c screw gives you.
My AGP lower came with the screw already tapped and installed, right in the trigger guard gap, not the pistol grip screw, for free. Either way, it does what the $150 triggers do - adjust the slack out for minimal creep.
Mine took out fractions of an inch of creep and reduced it to hundredths, and I saw no need to grind on the trigger bar, I didn't need that much reduction. If anything, you get more for your money with a set screw installation and a good 4 prong muzzle device than a $150 trigger on a field/duty gun. Recoil and muzzle blast is more important than a race gun trigger in the real world.
February 15, 2011, 09:20 AM
You can find the RRA two stage at the EE on ARFCOM for $80. Another very nice trigger is the ArmaLite NM or Tactical trigger, it is adjustable with three positions for the hammer spring legs. No set screws to come loose, no grinding and it's around $150.
February 15, 2011, 08:29 PM
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