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Posted: 7/15/2009 4:37:47 AM EDT
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Just had a rifle built.
The builder installed a Tapco single hook trigger it fails to reset every 100 rds or so. Are these triggers good to go or should I replace all together or hand fit this trigger to this rifle? Tapco piston is denting on the forward edge after only firing 200rds and yes the piston is riveted and has slight wobble. Why is the Tapco piston longer than the stock piston? Why does Tapco use soft SS on their pistons instead or making them like the combloc nations Hard Chromed steel? Is it cost I would gladly pay the difference for a US gas piston made to Combloc specs. Also do any Gunsmiths out there know the max firing pin protrusion on a 5.45x39? Thanks |
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if the cutout for the trigger and/or claw is too wide, the trigger can move laterally and bind on the clearance.
A too sharp disconnector claw or too sharp trailing edge on the hammer can prevent reset. A bent hammer spring can bind on the side of the disconnector. It is a mistake to think that any trigger group from any manufacturer is a drop in fit in every gun. I detail other possibilities and adjustments on my website under "notes." |
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Thanks for the response Gunplumber.
Its funny you mention lateral movement because there is lateral movement not much but a little. Could be a combo of what you mentioned above. I contacted Tapco they said they had problems with their triggers and NDS receivers which mine has.But I thought it was the NDS-3 only? They haven't seen any problems with their gas pistons mine is dented where the flutes are on the gas tube. |
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I have not found any receiver type - including factory chinese, & factory Romanian & bulgarian and Russian, that a TAPCO trigger does not need some adjustment. While the NDS-3 is generally more, it is not unique. I can make an unaltered tapco group double at least 50% of the time in any gun. And its not necessarily anything wrong with the parts - the .4mm factory spec gap between the disconnector and the hammer at rest is on guns that are retaining the hammer aft wiht the safety sear, that semis don't have. Remember that all tapco triggers are 2-claw. The 1-claw is a 2-claw with one claw cut off, but is the same geometry. the 1-claw like the bulgarian is a differnt geometry. Had to adjust the asenal too (for different reasons) but now arsenal has done some of the adjustment ahead of time (smell the cold blue?).
I have installed over 500 Tapco G2 trigger groups over the last several years and aside from a a few flukes (disconnector with no hole drilled in it, disconnector with hole too deep, etc), by doing the mods I show on my webside they fit fine and make for an excellent trigger pull. I used them in all 300 of NDS-3 builds I did last year. These mods take less than 5 minutes and result in a superb, smooth triggerpull. If the disconnector doesn't release, I can use the side of a scotchbrite wheel on the hammer without taking it out of the gun, and if its the disconnector I have a small dremel rubber abrasive wheel that fits inside the receiver and under the disconnector beak while still assembled. And a cutoff wheel sideways I can shorten the disconnector beak if needed, again, without removing the parts from the gun. So I do all the mods ahead of time, refinish them to match the gun (paint over park) and then I can make the occasional final adjustment after install. |
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Which leaves the question about gas piston denting.
I have a Tapco installed in my Ohio Ordnance AK-74 that's getting light dents on the front edge of the piston, and what may be denting in the inside rear of the gas tube where the flutes start. The piston IS hardened steel. The dents aren't deep, but they're there, after about 500 rounds or so of Polish surplus 7N6-PS.. Any ideas. |
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Is it a factory '74 piston or a TAPCO? The TAPCO is a 47 piston. It is NOT the same as a '74. I've used TAPCO US pistons on '74s, but only after turning off the first ring. While the bolt carrier + piston is the same OAL an the 47 and 74, the 74 piston is longer on the back of the shoulder and shorter in length by a quarter inch. While some have used them interchangeably, unmodified, I use the AK Builder '74 piston.
by the way, firing pin protrusion is min 1.4 mm max 1.52 mm |
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Mine is a Tapco stainless piston.
It is hardened, a file will skip over the surface. I'm getting a few random light dents on the forward edge of the head, and "possibly" light dents on the inside of the gas tube near the rear of the flutes. The piston seems to seat fully into the gas piston, and doesn't look at all short. It's welded on. |
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well, that's part of your problem - a welded piston does not have the necessary wiggle to prevent it from crashing into the edge of the gas block and raking the inside of the tube. They are supposed to riveted with up to 4mm lateral play. There is a lot of bouncing of the carrier as it travels back and forth and the deliberate inclusion of gas piston wiggle in the design allows it to find its happy spot.
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