Full Auto M16/m4A1 Resources

[Sparky5019]

Agreed. I thought there might be a market though I know it's a slim one. I figured if I was looking that there might be other looking for a good tool as well.

[JoshNC]

AFAIK there is no timing of a RR lower. I have two factory Colt M16s and I've never had to time them. A lower that's in spec shouldn't need anything. A RDIAS may require timing, which usually involves shimming the body and/or trimming the trip lever.

As for feeler gauges, the set used by HK to check bolt gap can be purchased through HK Parts and GMP Parts. It's made in Germany and very nice.

[Sparky5019]

AFAIK there is no timing of a RR lower. I have two factory Colt M16s and I've never had to time them. A lower that's in spec shouldn't need anything. A RDIAS may require timing, which usually involves shimming the body and/or trimming the trip lever.

As for feeler gauges, the set used by HK to check bolt gap can be purchased through HK Parts and GMP Parts. It's made in Germany and very nice.

There would not be any timing on a factory made MG lower. This would be due to the fact that they check them in house. If they don't meet spec, they don't leave. When you locate the AS hole from the selector hole and others in the AR-15 lower, things may vary slightly. I guarantee the factory checks the timing on hammer release by the AS; if it's not in spec, it's adjusted or if it's too far out of spec it doesn't leave. The hammer should release when the bolt carrier is 0.100" from the barrel extension as measured up through the mag well.

This lower is a brand that has been lauded here as GTG and it has a correct spec M16/M4A1 FCG pocket. It lacked the AS hole. We fixed that part. I have a low index of suspicion that the lower is out of spec. That was my purpose in choosing it as the prototype. I'll mill the FCG pocket into subsequent lowers. If the hole is off any at all then it will require some timing work. This on is dry releasing the hammer at about 0.089" best I can tell. Once I have the gauges done, I'll know for sure.

The reason I asked about a market for specific gauges was I couldn't find feeler gauges that were as thick as 0.110". There is a general lack of information out there on the subject. However, there is a bunch of information about troubleshooting guns that don't run. That's good stuff but much less on setting one up if. You do a 3rd hole style conversion and not a RDIAS. Technically, the issues are the same though the build and the technique is different.

Thanks!

[Renegade]

Does anyone here think there's a market amount 07/02 for the 3 basic feeler gauges used for timing; 0.100", 0.110", 0.080"?

Zero market, as there are no adjustments.

In 30 years of making/owning an M16, you are the first I know of to come up with this. It is a very forgiving spec.

[Iraqgunz]

I too am interested in the "timing aspect" since this appears to be a new concept. The lower and the corresponding holes for the hammer, trigger, sear, etc.. are either in spec or they aren't. It's really that simple.

[Sparky5019]

IG,

From what I've read...

As long as the holes are not grossly out of spec, things should be ok. The hammer is released when the BC is 0.100" from the BE when measured through the mag well. If much earlier than 0.110" then it could be problematic. If later than 0.08" then it will run slow and sputtering.

The adjustment is made by removing a slight bit of material from either the hammer side or the BC side of the AS depending on the whether it's early or late. Then use the gauge to recheck.

I would assume they at least gauge them at the factory and adjust them there hence a "factory" MG never having an issue for the end user as it would have been address before it left. A 3rd hole conversion, on the other hand, may exhibit an issue here or there because most FCG pockets and AS holes are hand milled/drilled instead of CNCd from the start. Even CNC parts have a tolerance to be off a minuscule amount.

Overall, my using the term "timing" may be better described at setting the hammer release on a 3rd hole conversion (or sample) over a factory MG.

My main question was more about info resources on the subject by FA armorers and possibly wear inspection measurements and such. Assuming if I wasn't able to find much info and gauges that others weren't as well that there might be interest in a decent quality set of gauges and compiling the info in one place for those interested in learning those techniques and details.

Thanks!

[Gunfixr]

I doubt they are adjusting parts at the factory to time them. That would totally destroy the ability of an armorer to replace parts, as they would then need adjusting.

If you really need something, industrial suppliers have ground steel stock in many thicknesses, and ground steel pins in nearly every diameter near the 100" level.
Autocorrect won't let me put the decimal where I wanted it above.

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[Sparky5019]

Never mind. Y'all haveCOMPLETELY missed my point. Thanks to those offered assistance.

[Iraqgunz]

I have never heard of this being done. But, by all means don't let me deter you.

IG,

From what I've read...

As long as the holes are not grossly out of spec, things should be ok. The hammer is released when the BC is 0.100" from the BE when measured through the mag well. If much earlier than 0.110" then it could be problematic. If later than 0.08" then it will run slow and sputtering.

The adjustment is made by removing a slight bit of material from either the hammer side or the BC side of the AS depending on the whether it's early or late. Then use the gauge to recheck.

I would assume they at least gauge them at the factory and adjust them there hence a "factory" MG never having an issue for the end user as it would have been address before it left. A 3rd hole conversion, on the other hand, may exhibit an issue here or there because most FCG pockets and AS holes are hand milled/drilled instead of CNCd from the start. Even CNC parts have a tolerance to be off a minuscule amount.

Overall, my using the term "timing" may be better described at setting the hammer release on a 3rd hole conversion (or sample) over a factory MG.

My main question was more about info resources on the subject by FA armorers and possibly wear inspection measurements and such. Assuming if I wasn't able to find much info and gauges that others weren't as well that there might be interest in a decent quality set of gauges and compiling the info in one place for those interested in learning those techniques and details.

Thanks!

[Sparky5019]

I have never heard of this being done. But, by all means don't let me deter you.

Ok. So let me be crystal clear here. What I'm curious about is what happens when an MG doesn't run perfectly at the factory. Do they scrap the lower if it only needs an adjustment.

Here is where OWNERS of factory MGs have less valuable info and BUILDERS of 3rd hole conversions can be helpful as well as factory armorers.

What do people do if the gun doesn't run? Scrap the lower? That can be an expensive proposition especially if it happens more than once. The conventional answer if the gun doesn't run is add an H2 and/or check the gas rings to prevent possible carrier bounce. Here's the rub though, what if the hammer is releasing early or late by the gauge? This is where the possible timing comes into play.

OWNERS of factory MGs never have this issue because this is checked before the gun leaves the factory.

IG, you've seen enough guns to know that, when parts go together, things aren't always perfect even with what we consider to be in spec parts. This is the narrow area that I'm inquiring about.

The lower I have in this situation is a Sons of Liberty GW lower with a FA FCG pocket, AS hole was drilled with a Bowers jig. Everything should be gtg as far as I can measure.

I'll be installing a Geissele SSF shortly so I'm not going to troubleshoot much further until then. My main question was about finding a good source of armorers' checks and procedures in one place like a manual or a compiled resource of some sort. Thanks!