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A&S Trigger Guard Swap-Out


Birdog19

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I bought myself the trigger guard before Christmas and when it arrived and my wife saw the price, she grabbed it from me, wrapped it and put it under the tree!  Merry Christmas to.., me?  From, me?  Giving and receiving at the same time!

While I have not stripped the M4 TG assembly 100 times like some savants may have on this forum, I have done it quite a few times to replace OEM with aftermarket parts, cleaning, etc.

The A&S TG comes with an over sized roll pin for the for the safety detent plunger and spring assembly.  You have to use that pin because the A&S trigger frame is sized for it.  It is a tight fit.  The TG also comes with a roll pin for the rear trigger over travel.  It too was a very tight fit and I decided to use the OEM pin.

The hole for the Trigger Pin Bushing was way too tight.  It required way more tapping (can you say hammering) to get it properly assembled.  I know, there is a lot to line-up in this process.  Once all put together, I noticed the Shell Carrier (Lift) and the Shell Release Lever were very stiff.  I had pushed the bushing through the TG too far which was causing friction and binding on the parts.  I backed it out and all worked properly.  I never had that problem with the OEM parts as there is just enough play in the bushing for all parts to live happily together. 

I did some safety checks with the TG assembling out of the gun to ensure the safety worked and the sear disconnect was functioning properly.  Once back in the gun, again everything worked as it should.

The tight tolerance of the Trigger Pin Bushing really bothered me and after sleeping on it over night, I decided to take it out and fiddle with it some more.  It was difficult to remove and required needle nose pliers and a screw driver to get it worked out.  I didn't have the right size punch which would have made it easier (later I found one in my shop).  Trying to re-insert the bushing into the TG alone without any of the other parts was impossible without a hammer.  I did manage to chip a piece off of the flared end (flange) of the bushing so I acknowledged that I may have done some other damage.  Just to see, I inserted the bushing back into the OEM guard and it went in easily as it always has.  So, off to the shop...

I took sand paper to the bushing holes on the A&S TG and opened it up a little.  It took time.  I also buffed out any self-induced imperfections to the bushing pin itself.  Eventually I was able to reassemble everything as I was previously accustomed by just pushing the bushing through with my fingers and the handle of a screw driver without and tapping or hammering, though not as easily as the OEM parts.   I'm going to order another Trigger Pin Bushing from Mid-West to replace the original that I may have buggered-up a little.

What did I learn?  

1)  I was surprised at the tight tolerances of the A&S guard and I'd never read anything about it on this forum.  Then again, I never did a though search for A&S.

2)  I also purchased the A&S lightened safety spring ($4.95) and it is nice.  Just about perfect for me.

3)  If I had found the correct punch for driving out the bushing I may not have buggered it up.  The right tools!

4)  Did I call A&S to ask them WTF?  No.  Did I ask anyone on this forum for advice.  No.  Stubborn?  Yes.

So, if you are going on the A&S Trigger Guard adventure and will be swapping out the parts yourself, I hope this missive will give you some insight and confidence as you proceed.  I also hope that any good advice from the 'wise ones' on this forum will chime in.

Thanks to Benelliwerks for his M4 Anatomy Manual and the Strangerous One for his detailed Trigger Group Assembly Guide!

 

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Sounds to me like you ruined a A&S trigger guard. 

By bushing pin, what one are you referring to?  If you sanded out any pin holes in the A&S there is a very good chance you have made a unsafe weapon. 

This thread was the first one I thought of when reading this..

It takes very little effort to make this gun Dangerous if you dont know what you are doing. 

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You shouldn’t have needed to modify the frame for the bushing for fit. My guess is the anodizing process changed the inside diameter of the bushing lugs. Did you remove enough material to remove the anodizing to bare aluminum?

Another possibility is that you damaged the bushing when removing the snap ring. If a bur raised, it might make the pin not fit easily. Sometimes shuffling all those parts to get the bushing pin holes to line up is trial and error. 
 

Hammering the pin in would not effect function. The bushing doesn’t rotate in the trigger frame. It just provides a method for the hammer, shell elevator and shell release button to pivot. 
 

I imagine you didn’t remove much material trying to sand inside the holes. So chances are you didn’t change the bushings position relative to how to hammer engages the trigger hooks. I’d fire a bunch of rounds before relying on it for defense and I wouldn’t chamber any rounds in the house until you’ve tested it to your satisfaction. 

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Pirate - I sanded the holes (lugs) in the TG where the Trigger Pin Bushing is inserted.  There is no play in the bushing or the parts it holds.  While I have not yet fired the weapon, everything functions as it should, trigger disconnect, etc.  and, it doesn't fail given the example you showed above.  I appreciate the feedback...time will tell after a bunch of rounds fired.

Stranger - I removed the anodizing down to bear aluminum.  I inspected the bushing for any damage or irregular shape and found nothing other than the aforementioned chipped flange end of the bushing.  All the hooks fully engage as they should.

Bottom line here (actually there are two), in just doing a fitment trial with no other parts involved (elevator, trigger, shell release) the bushing slides into both lugs (holes) easily in the OEM TG and with some resistance even after sanding the holes in the A&S TG ( a tight fit).  I don't have a micrometer to measure the diameters.

The other bottom line?  I should have called A&S when I discovered this problem!

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Mine went together pretty well.  The roll pin that holds in the detent and spring for the safety was stupid tight.  Really out of control stupid tight.

I also purchased the lightened safety spring.  Although it could be a hair stiffer for my taste, it’s much better than the OEM.  The factory safety spring is not that user friendly IMHO.

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27 minutes ago, Milspec said:

Mine went together pretty well.  The roll pin that holds in the detent and spring for the safety was stupid tight.  Really out of control stupid tight.

I also purchased the lightened safety spring.  Although it could be a hair stiffer for my taste, it’s much better than the OEM.  The factory safety spring is not that user friendly IMHO.

'Spec -

As I recall, you swapped to an A&S TG within the last few months, right?  Agree, the safety pin was stupid tight, yet you had no problem with the trigger bushing?  I wonder if their anodizing process is adding too much thickness in certain areas (holes)?  I'm no expert on the subject!

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18 minutes ago, Birdog19 said:

'Spec -

As I recall, you swapped to an A&S TG within the last few months, right?  Agree, the safety pin was stupid tight, yet you had no problem with the trigger bushing?  I wonder if their anodizing process is adding too much thickness in certain areas (holes)?  I'm no expert on the subject!

Yes, BD.  I changed it over to the A&S 3/4 months ago.  I don’t remember having an issue with the trigger bushing.  My main challenge besides the safety roll pin was the snap ring that retains the bushing.

I didn’t have a good quality pair snap ring pliers at the time.  I had some difficulty removing that bushing snap ring.  Since then I invested the $20+ and upgraded my pliers.

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5 hours ago, StrangerDanger said:

I’d contact A&S to see what they say about it. I’ve been together probably 25 of these A&S frames and have never had one with fitting issues you described. 

I sent them an email via their website and mentioned that I received some feedback on this forum with others that have installed their TG.  We'll see what they say.  And, thanks!

 

4 hours ago, Jolly Roger said:

Do you have a set of digital calipers? Id be happy to compare hole and pin sizes. ?

This bushing? 

Comparing holes and pin sizes..., I think you're on the wrong website ?  Ha!  I appreciate the offer but my wife won't let me have digital calipers!!  Maybe I should go get some anyway.  Yes, the bushing in question is the one you have highlighted above (arrow).

Thanks for the offer and the assist.  I might just go get me some of those calipers.

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15 hours ago, Jolly Roger said:

Ok, my spare "pos" calipers dont fit into a small flat rate box☹️  I was just gonna mail them to you.  For the cost of the next box size you might as well just go to Lowes and buy a $20 pair a cheapies. 

let us know what A&S says...

Thanks Jolly!  Appreciate the thought and the effort!

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  • 2 weeks later...

Alright, let's kill this thread!!!!  Thanks Jolly for the offer, I bought some calipers from the Big River Store in South America and did a little examination.

OEM trigger guard hammer bushing (pin) hole diameter:  0.2365"

A&S trigger guard hammer bushing (pin) hole diameter AFTER sanding the lugs and removing the anodizing:  0.230"

A&S was pretty responsive considering I was emailing them over the holidays.  Fred Snyder from A&S called me after seeing my measurements and commented that the holes should be 0.236.  He sent me a new TG and asked that I return the original purchase for his inspection.  I just swapped-out the parts and all is well.  Quite well.  The Safety Spring Retainer Pin was pretty tight, but no worries when I snugged the TG in a vice for more precise work.  The Hammer Bushing (I like that better than Trigger Bushing) slid into place easily and as expected.  Function checking the trigger, disconnector and hammer all went as expected -- in and out of the gun (though I have not fired it yet).

Bottom Line:  A&S gave great support and is looking into what may have caused the problems in their tooling or anodizing....if any.

Thanks All, and to All a Good Night!

P.S.  I broke one of my Golden Rules...Do a search for your M4 issues on this forum before posting a new topic and asking questions!
 

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Hey guys, I'm sure some of you have already seen some of my posts in the other topic of the disconnector problem but figured I would ask this here since it pertains to the A&S trigger housing vs starting a new thread.

So I just put in the FFT trigger group into the A&S housing and all seems to be functioning correctly when doing numerous functions checks by manually resetting the hammer before putting it back into  (safety first!).  After installing the assembled FCG back into the gun and function testing, looking into the ejection port, the hammer seems to be almost "bouncing" back after hitting the firing pin.  The hammer definitely feels like it has much more freedom of movement (rotating on the bushing) than when it was in the OEM polymer housing.  

I'm sure everything is fine but just want to get some input and make sure that this is normal before going out and firing.

Thanks!

P.S. - I don't think my wife likes you guys, just ordered my 3 position recoil tube ?

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On 1/13/2020 at 6:11 PM, Jolly Roger said:

Cool, glad you were able to figure it out. What a headache! I bet it feels great to have her all up and running again! ? 

Headache?  Yeah, true that, but always fun to be tinkering and measuring and seeing what you guys say and suggest and buying calipers for $25 and attempting to give feedback to a vendor that is trying to fill a niche market with a quality product.  All good and thanks for the assists.

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