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Posted: 10/23/2009 6:02:22 PM EDT
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So my build's gone without too much of a problem.
I have about 140 rounds through my M4gery and everything seems to be going well, but my shooting session ended yesterday when the trigger pin worked its way into (one side) of the lower reviver, rendering my trigger inoperable. I had no tools with me at the time. Looking at it today, while I was installing goodies  , I easily worked the pin back into place using a punch and my finger. Function checking, the rifle is flawless after numerous cycles. I then noticed that the pin may seem too loose (this is my first AR though, I'm not sure what they're 'sposed to be exactly like). However, when the rifle is cocked the trigger pin seems much stiffer in place...though I could see how successive shots loosening in the interim could cause it to work its way out = Fail.
What do you think I should do? Several solutions come to mind (mind lock-tight, just breaking it in more, try different pin) I know that different pins can have slightly different tolerances. I'm running a S&W lower and a DTI PPK and I've never heard of issues. Thanks all, happy weekend. |
| Was the hammer spring installed correctly? Does the trigger pivot pin have a retainer groove in one end? The pin is probably out of spec. I would try a different pin. If you experience the same problem, you may want to try a .155 Colt pin as a way of eliminating other problems. |
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^^^
This. If it's indeed the trigger pin, make sure that the hammer spring is resting on TOP of the trigger pin, and that the spring is sitting in the groove on the pin. If it's the hammer pin, make sure there's a retaining spring in the hammer, and that the pin has the groove dead center on the pin. It's very unusual for a pin to come out of a semi-auto, when properly installed, even if it's slightly "loose" in the receiver holes. |
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Thank you for your responses,
I installed the hammer spring (correctly, as far as I know) and have done total function checks as well as shooting over 140 rounds without experiencing this issue. The trigger pin has slots on both sides where the spring ends seem to be meant to rest. To me it look like the tips of the springs are resting higher for whatever reason...I'll post picture up tomorrow if it's still being an issue. ...it has just occurred to me that the coiled portion of that spring may be bent in a manner as to prevent the tips of the spring from resting in the slots; as I may have bent them during LPK install while wrapping them. I'll also look into the Colt pin. Thanks for all the past and continuing help. D. |
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The usual pin diameter is .154, but on some lowers (as mentioned above) it's .155. And a lower that starts out at .154 can get honed out to bigger diameter due to the pins rotating, but this is usually attributable to many, many, many rounds down range!
There are anti-rotating kits (KNS makes popular ones), that also "hold the pins in." And they come in .154, .155, and .177 (if I remember right...) I am curious to see your picture, the spring should ride on the pin, and engage the slot... Bottom line, it's fixable, and you've got options! |
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Will do;
My friend with a nice D200, some lenses and some filters wants to take some pictures within a couple of days. I'll make sure he gets plenty of the sping(s) in question. Trust me, it's spec. When I put the rifle back together I swapped the hammer pin and the trigger pin, which seems to have helped a lot. I've also made sure to ensure that the spring tips are actually down on/in the trigger pin. Complete function test is good with no movement of pin. Thanks to everyone for their responses and help. Range report (of my totally actually wholly finally [1st, M4gery] completed build) tomorrow; *DTI M4 upper, LPK and 16" M4 barrel (M4 feed ramps, flattop upper, and unused detachable carry handle) [North Carolina FTW] *S&W lower receiver *DD 7.0 Omega FF *M4 A2 front sight attached M4 (carbine) length gas system *EOTech 512 *GG&G rear BUIS *Six-point M4 collapsible stock, that rattles too much and need to be replaced with the Magpul CTR I think (is it as stiff as Vltors?) - *Houge pistol grip *Magpul 'M' PMags (30 rd), one PMag20 that I'll actually use *Magpul XT rail covers on L, B & R (super-pain to install, great to have on. May have done more damage to my rail during their install than they'll prevent down the road but ther's no way I'm taking them off to check); DD ladder rail cover cut to cover the rail in front of the EOTech *Vltor right-handed endplate, HK hook; single point sling with bungies Lots of pictures to come...including the guts which will be presented here first. |
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Quoted:
Quoted:
Does your hammer have the j pin in it? I'm still too much of a newb to know. I have a Del-Ton hammer, like this one here: http://www.semperfidepot.com/PDGImages/lpk.jpg The J spring inside the hammer holds the hammer pin in. It doesn't affect the trigger pin at all. My guess, as you have determined, is hammer spring installed upside down. I did the same thing on my 9mm build. It worked perfectly but the trigger pin walked out. There's more downward force on the trigger pin with the hammer spring installed correctly. This pic shows the spring installed upside down. Notice how the leg of the hammer spring is coming from over the top of the hammer pin. It should protrude to the rear from under the hammer pin. 
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Here's a pic of the hammer FYI
The J sping is that little piece of wire you can see in the small upper hole. If you look inside the hamemr pin hole you will see that same little wire on the side of the hole. (not visible in this pic) That is what holds the hammer pin in, in the center notch of the pin. 
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