Couple Of Function Questions

[Big John! 2,062]

I had a terrible day at the range yesterday. Fired steel shot no problem. I usully am able to fire federal 7 1/2's with some reliability. I pulled the plug and while it was really dirty in there, I started to take a good hard look at my 4 holer. My question is... The 4th hole is so far forward that while it's not obstructed, it seems that it is right on the verge of being under the gas block which makes me wonfer if I'm actually getting gas benefit from it? Also, it's my understanding that we are NOT suppost to grind away at that lip that it's next to... Yes? You can see the pick in the hole and I can get it all the way in, so whatcha think???

 

 

My other question is... I see many peoples bolt close with zero issues. I read a couple of threads on this, but found no answers on how they got this to happen. Mine is really close, but I have to tap it a few times to get it to close. Click the link for video...

 

http://s630.beta.photobucket.com/user/bigjohnoi812/media/CA398B38-311A-4026-849D-8ACF9FA67D3A-1079-0000016849BD789B.mp4.html

Edited January 17, 2013 by Big John!

[sapper1371usmc 107]

Just because you have 4 ports doesnt mean theyre the right size. Your probably good to go with the location of that port. And your bolt hanging up doesnt mean anything. AKs arent meant to be gently "rode home". Just let it fly

[sapper1371usmc 107]

To know for sure if your ports are properly sized and not covered, remove the gas block, and once removed, you will see a circular area with paint overspray/carbon build up. If all your ports are located within this area, then your good to go. Next check your ports. You should be able to insert a #49 wire gauge bit (.073) inside. If it wont fit, enlarge ports using this bit at a 45* angle

[sapper1371usmc 107]

If converted. You need to at least reduce the drag between the hammer and bolt carrier by reprofiling the hammer and smothing the angular edges on the bolt carrier. You can also send your bolt off to one of the vendors here and they will perform the service for you fora small fee but the results are worthwhile

[Big John! 2,062]

I was trying to get away without dicking with the block. I've done some polishing and a small amount of reprofiling. I'll see more how that works here in a few days when I put the Tromix FCG in.

[sapper1371usmc 107]

So your gun is unconverted? If thats the case, its more than likely your port size, as the factory hammer doesnt exert as much pressure on the carrier due to having a slightly different shape. Its the Tapco triggers that cause alot of un-necessary friction in the gun as theyre designed as rifle triggers.

 

I would get the gun running good before you convert it.

[sapper1371usmc 107]

I was trying to get away without dicking with the block. I've done some polishing and a small amount of reprofiling. I'll see more how that works here in a few days when I put the Tromix FCG in.

And the Tromix version isnt going to help either. All they do is remove the "hump" and clearance the right side of the hammer for the BHO lever. They do not reprofile the hammer surface that rubs against the BC

[gunfun 3,931]

1) un covered is uncovered.(so long as your selector plug indexes correctly to put the wedge cutout over the opening) Gas flow will go wherever. If you can get a pick in it, it is uncovered enough. Doing more will not help at all.

 

2) For the overwhelming majority of people, removing the block is a 20 minute job that can be done with a couple of blocks of hard wood or soft metal, a big hammer and a small punch. For me getting the trigger group in was a much bigger hassle. The worst that can happen is you punch out the pins and find the block is too tight. Then you just put the pins back and squirt in some penetrant oil and wait untill you can borrow an air hammer or shop press. - upshot- it can't hurt to try.

 

Just do the following:

=Get a clamp or buddy to hold the gun upright while knocking the block.

=scribe a line on the block and barrel to find the proper home spot and orientation.

= punch out the pins. keep the gas plug on there and turned so as to retain the retainer. (remove carefully before re-installation.)

= put the barrell on a block of wood

=put soft metal or hard wood on the block and alternate sides

 

do whatever you have to do to the ports- I believe in small steps

 

= re install in reverse order with the gas plug off. oil helps. so does polishing up the barrel area.

 

when you are almost home, put the gas tube in place and check alignment with each blow. You don't want to munch that.

= put the retainer back, and hold it in place with the gas plug.

=put the pins back.

= test.

= if needed rinse and repeat a small increment larger.

 

Also, do this testing without your UTG rail. sometimes those cause problems.

[Big John! 2,062]

How does the rail cause problems???

[sapper1371usmc 107]

Some say they cause binding.

[Guns4Gods 1]

I know if you block the gas hole on the side of the block it can cause issues but could you explain what would cause this binding ? What binds up ? & how ? Thanks

[gunfun 3,931]

It clamps on the gas tube and can torque a straight one crooked as the gun heats up, or a crooked one straight...

[Big John! 2,062]

Just so I'm very clear and don't want to over gas... .073 is the magic number for 4 hole guns?

[Big John! 2,062]

I pulled the gas block today. Mine was very easy to get off. I used a chisel on the lug where the bottom screw goes through like Evil suggested. Worked like a charm and didn't even mess up the finish. The ports were very close already, but I opened them up to .073.

I took it out and shot it and had several FTE's, but I'm starting to think it was an ammo problem. i shot Winchester 7 1/2's with no FTE's. Shot Federal 71/2's out of one box and had no problems. Only had problems with a certain batch of Federals. When it did eject it shot the shells out six feet.

 

I still feel like it's slightly undergassed though. Should I open the ports more than .073??? Only thing I didn't do was run it without the UTG rail.

[sapper1371usmc 107]

4 ports at .073" is slightly more than 3 ports at .09375" and I never once had trouble getting my guns to run 100% on any of the three walmart bulk brand low brass ammo. If you do, go up to a 5/64th bit (.078125") and do one hole at a time and re-test. Have you ever done any reprofiling/polishing on your internals? What gas puck/gas regulator are you running? Are they stock? If it was me, I would return the gun to the original configuration before doing anything else.

 

 

Edited January 19, 2013 by sapper1371usmc

[gunfun 3,931]

4@ .078" to 4 @ .093" is they usual range of where they start t work right. Smaller is better if it works. I say try 4@ .078 then .084 if needed, then .093...

[sapper1371usmc 107]

.093" is the standard for 3 port guns. It's your gun, but I wouldnt drill 4 ports at .093". I know some here run their guns this way, but it isnt necessary. Again, 4 ports at .073 as a total surface area of .292" which is more than the .28125" of total surface area when you have 3 ports at .09375". I suspect one of the main reasons most here start at 4 ports at .078 is that they dont usually have the #49 wire gauge drill bit that is the correct size and opt for a 5/64th bit instead. If you do go that large, make sure you have a good plug to regulate the gas flow so as to not beat up your gun.

[Big John! 2,062]

4 ports at .073" is slightly more than 3 ports at .09375" and I never once had trouble getting my guns to run 100% on any of the three walmart bulk brand low brass ammo. If you do, go up to a 5/64th bit (.078125") and do one hole at a time and re-test. Have you ever done any reprofiling/polishing on your internals? What gas puck/gas regulator are you running? Are they stock? If it was me, I would return the gun to the original configuration before doing anything else.

 

I've taken the hammer down just a little. The plug and puck are stock. I'm keeping it that way till it is 100%

4@ .078" to 4 @ .093" is they usual range of where they start t work right. Smaller is better if it works. I say try 4@ .078 then .084 if needed, then .093...

My next drill bit is .076. I'mma run it with the stock forearm, if that doesn't work, then I'll break out the drill bits.

 

.093" is the standard for 3 port guns. It's your gun, but I wouldnt drill 4 ports at .093". I know some here run their guns this way, but it isnt necessary. Again, 4 ports at .073 as a total surface area of .292" which is more than the .28125" of total surface area when you have 3 ports at .09375". I suspect one of the main reasons most here start at 4 ports at .078 is that they dont usually have the #49 wire gauge drill bit that is the correct size and opt for a 5/64th bit instead. If you do go that large, make sure you have a good plug to regulate the gas flow so as to not beat up your gun.

I do NOT want to over gas the gun. I'll try other things like pulling the UTG first. The only reason I would consider going larger is that front hole. It's so far forward that I seriously wonder if it's catching the puck properly.

 

You guys have been a great help so far. THANK YOU!

[sapper1371usmc 107]

Some have even had problems with the factory gas regulator having poor machining tolerances, causing cycling or overgassing problems. Here look at MD Arms product detail when talking about his V-plug:

 

http://www.mdarms.com/index.php?main_page=product_info&cPath=13_1&products_id=16

 

So dont rule that out either. But I would say if your gun is cycling winchester universal 100%, then your gas flow is pretty good, port size-wise. Winchester is considered the weakest of the 3 bulk brands at walmart. Federal is considered to be a better performer when it comes to cycling the action. You could of just ran into a bad batch.

 

Anyways, if you do decide to open up the gas ports some more, I would do so in moderation. Maybe one or two ports at the most at one single time, then go out check for function. Its tempting once you have the gun dissassembled to want to just open them all up and be done with it. But you are almost there.

[Big John! 2,062]

Some have even had problems with the factory gas regulator having poor machining tolerances, causing cycling or overgassing problems. Here look at MD Arms product detail when talking about his V-plug:

 

http://www.mdarms.com/index.php?main_page=product_info&cPath=13_1&products_id=16

 

So dont rule that out either. But I would say if your gun is cycling winchester universal 100%, then your gas flow is pretty good, port size-wise. Winchester is considered the weakest of the 3 bulk brands at walmart. Federal is considered to be a better performer when it comes to cycling the action. You could of just ran into a bad batch.

 

Anyways, if you do decide to open up the gas ports some more, I would do so in moderation. Maybe one or two ports at the most at one single time, then go out check for function. Its tempting once you have the gun dissassembled to want to just open them all up and be done with it. But you are almost there.

Opening it up will be my last resort. I said fuck it and converted it today, so I may be chasing gremlins for a bit. I need to take a close look tomorrow at the range at the indexing of the plug. I'm pretty sure that's a little off. I took some material off the hammer and polished it a little before installing. Unless I'm missing something, it seems one could take an assload of material off before it would be a problem

[gunfun 3,931]

There is a picture in the trigger related link in my sig that shows proper hammer profile. Basically though, 1) you want: the carrier to push it at least a sixteenth lower than the disconnector, 2) When the bolt is home and the hammer is pushed forward as if firing that the plane of the hammer face striking the firing pin is the same angle as the tail of the firing pin, not slanted. As long as it is a smooth curve and those conditions are met, you are pretty much free to do what you want to the hammer strike face. While you have it out, smooth those engagement surfaces with a ceramic knife sharpener or a very good diamond stone. Keep the factory angles exactly though. It took me about 15 minutes to stone up my G2, and made a much smoother trigger. With the other mods, it is as nice a trigger as many a fine rifle has.

 

Use the factory hammer as a general guide. Rough it in to just a bit bigger curve than the factory hammer, then go slow the last little bit and make sure the angles match. Keep in mind that the hammer is deliberately soft metal and tends to get beat in as you use it. So leave a little more than the bare minimum of material that will reset.

 

Also be less afraid of the gas ports. It is really no biggie. Installing the trigger group the first time was a harder job. if you put your ports at 4 @.084" you would be in no risk of overgassing it or gunking up your gun. even .093" is safe from the gassing perspective even though it runs dirtier.

Edited January 20, 2013 by GunFun