I can see where that could be a problem, but I'm not sure it is the whole problem. I am very new to the SA42 and have my own M53 based 8mm/308 rifle in the works, but I worked for ten years as an armorer at Bushmaster and I do have a pretty decent understanding of the AR fire control system.On the AR, the hammer and trigger holes are made to very close tolerances, like the exact center of the hole has to locate inside a circle only .003" in diameter, and the rest of the tolerances in the fire control group are almost as tight. This doesn't really translate to the SA42 rifles since nothing on these seems to be very exact except the trunnion/bolt head tolerances. It would be pretty easy to inadvertantly set one of these up so that the hammer was being driven down too far, thereby causing the problem mentioned above. Even more so since every one of these is slightly different with regards to the grip/bolt relationship since alterations have to be made in this area to prevent the FA parts from fitting.I am a here since I have yet to get my gun running and I have no doubt that in some AR FCG guns limiting the trigger travel will help alleviate the trigger slap, but there may be more to the problem in some other guns, particularly those where the bolt rails are mounted slightly low in the reciever or those where the bolt may not have enough removed on the bottom pad. These will most likely hit hard no matter what since the hammer height dimension is being altered. I'm just offering up an alternative solution that may help in some cases. By the way, I'm using a FAL FCG group and radiusing the back of the bolt in mine to prevent this from happening!
Im sure I need to grind more off the bottome off my bolt. My rails are VERY low, as evidenced by the fact that I had to grind the hell out of the outside of the recouperator to get it to fit in the channel. I just didnt want to admit that to anybody yet
My soultion for everything "Get a bigger hammer or larger caliber!"
grind off the bottom of the bolt. leave enough material at the rear to cock the hammer then grind off the flat in the front till it is down to the bolt carrier diameter.
I took a good look at it tonight. When the bolt comes back and resets the trigger, the disconnector is pushing against the trigger real hard. I ground the bolt, and I ground the bottom of the disconnestor part that sits in trigger. It was still hitting so I ground a bit off the disconnector notch on the hammer. OOOPSIE. Too much. Disconnector not working anymore. Looks like its time to buy some new parts and try again. Damn, and I was gonna take her to the range tomorrow. Ill bring the 1919 but thats just not as cool!
My soultion for everything "Get a bigger hammer or larger caliber!"
Sarco has treated me well in the past for surplus parts, they probably have m16 hammers you could get pretty reasonably. I'd try leaving the disconnector engagement alone and going after the back of the hammer instead. That would be much more forgiving if you took a little extra off. If you're worried about the weight you could even slot the rear of the hammer to clear the disconnector and leave the rest full profile. Hope this helps.
are you grinding on the hammer and disconnector to eliminate the trigger slap? If so, you are going the wrong way. The correct resolution to this problem has been explained to you in this post. Either install the original AR15 safety selector, or put a pin in its place to limit the trigger travel. Simple as that. I had Richard locate and drill the hole for the original safety and installed a 3/8" dowel pin and ground a notch in the
bottom to give the right amount of clearance for the trigger to trip the sear.
If you do a standard semi auto functional safety check you will see what is happening.
Pull out the grip. cock the hammer. pull the trigger and keep pulling the trigger. try to reset the hammer by pulling the hammer all the way back. you will see that it will kick your trigger and finger forward. You are getting too much travel in the trigger because there is nothing to limit the rear part to the trigger to stop it. As the trigger pivots, the rear part of the trigger travels upwards. The original safety limits this travel. If you have an AR15 laying around. You can see how it works.
also, I used a DPMS AR fcg and hammer and had to grind nothing.
If I understand correctly I need to limit the travel of the trigger, in ways of how far you can pull the trigger back? So a stop or dowel above the rear of the trigger will work? Ive looked at it all night and it seems to make sense...
BTW I ordered parts from Sherluk marketing...they always seem to have the best prices. Good people.
My soultion for everything "Get a bigger hammer or larger caliber!"
ScottD wrote:If I understand correctly I need to limit the travel of the trigger, in ways of how far you can pull the trigger back? So a stop or dowel above the rear of the trigger will work? Ive looked at it all night and it seems to make sense...
BTW I ordered parts from Sherluk marketing...they always seem to have the best prices. Good people.
Yes!
limit the the trigger pull just enough so that
1. when the trigger is pulled and held to the rear, the disconnector will still catch. and 2. that the trigger will trip the sear when pulled for normal operation.
and that my friend will eliminate the evil trigger slap that takes all the fun out of it.
Like I said, I installed a 3/8" hardend dowel pin and ground a notch in the bottom to allow the proper travel. However, some of my friends up here installed a screw angled down from the rear to act as a stop so they could make fine adjustments.
Well, none of it matters till my new hammer and disconnect get here this week. Lesson learned. You should have seen the looks on my parents faces when they walked into my gun room and saw the 42 sitting on the tripod.....bawoohahahaha!
My soultion for everything "Get a bigger hammer or larger caliber!"
Hey Tomcat, Ive given it some thought, and Im gonna try a small set screw UNDER the trigger, up front. (below where it sets on the sear) I think this will be the simplest and least invasive idea. Thanks for the input. Man I love this gun!
My soultion for everything "Get a bigger hammer or larger caliber!"
Scott, there seem to be two schools of thought here as to exactly what your trigger problem might be. Either fix may solve your problem, but how to tell? I think the following may help you to decide.
Remove the pistol grip, put the bolt forward. Turn the gun upside down, measure the distance from the bottom of the bolt to the outside of the receiver. Then take your pistol grip, cock the hammer, and pull the trigger gradually until the hammer releases. Hold the trigger right there, that is the point where your sear releases, and the exact place that the trigger (and your finger) should be when the gun fires.
Now, without moving the trigger, cock the hammer down past the disconnector(may want to remove the disco for this measurement) until it touches the top of the trigger, and hold everything right there. With your third hand (yep, another 3-hand deal) measure the distance from the top point of your hammer to the top of your pistol grip, and add the distance between the grip and receiver, if any (a feeler guage would be ideal for getting this measurement). If the hammer distance is more than the bolt distance, your bolt is riding low and you have to cut something. If it is less, then a dowel pin or set screw limiting the trigger pull will solve your problem.
Measure twice, cut once, because parts and alterations are expensive and measuring is cheap. I'd suggest repeating the measurements several times and taking the average, since this is not exactly a precision measurement method. If you happen to have machine clamps and some fine-thread rod you could make a fixture to measure this exactly, but the above method should put you in the ballpark, at least.
Thag say your method too difficult for Infantry guy. IM gonna go with the trigger limit screw for now, if that doesnt work then Ill just tape some foam on the trigger!
My soultion for everything "Get a bigger hammer or larger caliber!"
well, I know of at least 5 guys and possibly more that had the "known" trigger slap the heck out of your finger problem with the MG42 style grip of pbb....and we all did the same fix. It's a simple fix !This is a known issue and even Robert thompson aka panaceabeachbum the manufacture of the grip will tell you the same thing.
I went with the set screw under the front of the tigger. Once I get the new parts Ill get her all set up for a nice break point and loctite the screw in. Ill let you know how it works.
My soultion for everything "Get a bigger hammer or larger caliber!"
here since I have yet to get my gun running and I have no doubt that in some AR FCG guns limiting the trigger travel will help alleviate the trigger slap, but there may be more to the problem in some other guns, particularly those where the bolt rails are mounted slightly low in the reciever or those where the bolt may not have enough removed on the bottom pad. These will most likely hit hard no matter what since the hammer height dimension is being altered. I'm just offering up an alternative solution that may help in some cases. By the way, I'm using a FAL FCG group and radiusing the back of the bolt in mine to prevent this from happening! 
