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Gas port next step recommendation


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I've got a 3 port gun that I've personally ran a new 3/32 drill bit through to confirm the size that I'm now considering adding a little more gas. Reason for wanting more gas is because it seems as though I've had to fully tighten the autoplug adjustment screw to the max to get the Federal 7 1/2 value pack to cycle. Personally, I'd rather have a little more adjustment in the autoplug for when I run slugs at an occasional match. I know the debate about high brass loads, but shooting the cheap stuff in mass quantities is where I have more fun with this rifle. Plus, I'm having to share it with everyone at the range and don't want them eating up the expensize loads cause everyone wants to shoot it.

 

Pauly's service has been done on my bolt/hammer/pins. I've got nothing added for weight to my charging handle. Springs are all factory. PUC was changed to a CSS Performance which did improve reliability. There's several other things that I've checked on the rifle, but not sure that I can list them all.

 

What I'm looking for recommendations is to whether just increase the one or all three holes to the next size (ie. 7/64) or would you recommend adding a 4th port of a smaller size. I don't want to go too large that I get too much crud in the gas chamber, but I'm also worried about weakening the area by adding another hole. I know that this is kinda hit-or-miss, but I also don't want to keep breaking this thing apart to re-drill and was hoping to hear from others.

 

For those whom opened their ports to just one size larger (ie. 7/64), do you find the crud to be a problem?. For those whom added a 4th hole, what size did you go with on the 4th hole?

 

Thanks in advance...

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Mine is a 3port and mine has two at 3/32 and the center hole is 7/64. Mine is fine I ran alot of buck and slugs and mine is fine, it has been two years now. It does not get crazy dirty. I even use remlube on my stock and KA puck and it does not gum up like people on this site say's it will.

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I do believe that the pros round'about here, would say that drilling another normal sized port is preferable to opening up all the existing ports if they're not undersized/partially obstructed.

However, I think the suggestion of opening one port, is a good one. Perhaps one of the forementioned pros will offer their $0.02.

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I opened my 3 ports to 7/64. The gun runs great, but I do get a bunch of crap in the gas chamber. It's probably also beating itself up a bit harder than it needs to (bolt to rear trunion).

 

The factory ports were undersized, but I went to 3/32 and then to 7/64 without even testing the correct port size first. I had my reasons at the time, but if I were to do it again, I'd stop at 3/32, that should be plenty for most guns based on feedback I've seen here.

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I had a three-hole that I took to 7/64, the gun ran awesome but I had to clean out the gas block every 250 rounds. I DO NOT recommend doing this. Try the booster puck first, that's want I'm running with this current S-12, booster puck and autoplug and I have no problems with bulk ammo.

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Thanks all. Sounds like opening a port to 7/64 would be the easiest route, but anymore than that and I'd most likely be causing too much crude. Because I didn't mention earlier, let me just clarify that none of my three ports are obstructed and that my last shooting was with the CSS booster puck.

 

So if I were inclinded to take the "hard route", anyone got any prior experience with adding a 4th hole regarding which size seemed to work. If I had to guess (which is exactly what I'd be doing), I'd probably go with a 4th hole of the correct angle at a size of 1/16. Right? Wrong? Maybe?

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Dudes...I see a lot of folks going from 3/32" to 7/64"...there are six other drill sizes in between (#36 - #41), as well as four metric sizes (2.4mm - 2.7mm) Just wondering if somewhere in between would be a better option....you're increasing the diameter about 0.0156" per port going from 3/32" to 7/64".

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Dudes...I see a lot of folks going from 3/32" to 7/64"...there are six other drill sizes in between (#36 - #41), as well as four metric sizes (2.4mm - 2.7mm) Just wondering if somewhere in between would be a better option....you're increasing the diameter about 0.0156" per port going from 3/32" to 7/64".

 

My drill index goes from 3/32 to 7/64 with nothing between them. Not all of us have invested in extensive bit kits. I mean, I don't see the point since I'd never use most of the bits anyway...

 

Thanks all. Sounds like opening a port to 7/64 would be the easiest route, but anymore than that and I'd most likely be causing too much crude. Because I didn't mention earlier, let me just clarify that none of my three ports are obstructed and that my last shooting was with the CSS booster puck.

 

So if I were inclinded to take the "hard route", anyone got any prior experience with adding a 4th hole regarding which size seemed to work. If I had to guess (which is exactly what I'd be doing), I'd probably go with a 4th hole of the correct angle at a size of 1/16. Right? Wrong? Maybe?

 

From someone who has BTDT, let me tell you that I would add the fourth port, it's not really that hard, just use a center punch on the barrel where you want the fourth port so you can start the bit at an angle.

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I've read that getting another hole in the barrel isn't really that tough of a job. I'm not worried about that aspect. I've got the tools and a drill press, although my apparently limited set of drill bits does jump from 3/32 to 7/64. Plus, I'm not really worried if I need to open the hole in the gas block if the 4th hole needs some breathing room.

 

I think that I've done about all the reading on this subject that I can, but I'm just at the point of looking for anyone's recommendation as to what size the 4th hole should be drilled.

 

Here is my logic: Sounds like 3 hole guns enjoy the 3/32 port size, where the 4 hole guns enjoy the slightly smaller 5/64 port size. So my guesstimate here is to keep my 3 existing 3/32 holes and add another even smaller 1/16 hole for a total of 4 holes.

 

That's the plan for this coming weekend's activity, although it'll be another week or so before I can get to the range to test. Thanks...

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4 @ .093" works great as long as everything else is in check.

Just don't run 3" shells with a manual regulator in the wide open position and you will be fine.

 

4 @ .080" is still limited in which ammos you can run with MD-20 drums, from my experience. Smaller holes tend to clog easier as well. My standard of "reliability" goes a bit further than what it takes to satisfy most people though. At least 100 rounds of bulk ammo in MD-20s flawlessly is what I consider acceptable reliability.

 

evl....

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My drill index goes from 3/32 to 7/64 with nothing between them. Not all of us have invested in extensive bit kits. I mean, I don't see the point since I'd never use most of the bits anyway...

 

I understand...however, I didn't say anything about "investing in extensive bit kits". I simply suggested using one of the in between sizes, which are readily available and inexpensive. If you are going to drill out one or more ports, wouldn't it be better to do it gradually? Once you drill it out too much, there's no going back.

 

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My drill index goes from 3/32 to 7/64 with nothing between them. Not all of us have invested in extensive bit kits. I mean, I don't see the point since I'd never use most of the bits anyway...

 

I understand...however, I didn't say anything about "investing in extensive bit kits". I simply suggested using one of the in between sizes, which are readily available and inexpensive. If you are going to drill out one or more ports, wouldn't it be better to do it gradually? Once you drill it out too much, there's no going back.

 

I understand but I've never in my life seen the six drill bits that you are referring to... Maybe our hardware stores here in Texas aren't as well stocked as they should be. What are these six sizes and where did you get them?

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Quick update on the route that I took.

 

After removing the gas block, I had decided to drill a 4th hole of 3/32. But after looking at the triangular pattern of my current 3 holes, I was going to need to open the hole in the gas block to allow a place for the 4th hole. So I started getting some measurments from what would be un-obstructed with my autoplug, and I realized that I CANNOT expand the gas block hole towards the gas block threads any further or it would be under the autoplug. Then I thought about moving it towards the breech, but I can see where the puc moves around and there isn't a lot of room there either. So my last consideration was to place the 4th hole more to one side of the gas block, but I wasn't crazy about what that would require either.

 

So after all of those "good intentions" to make this a 4 port gun, I ended up drilling out just one of the holes with a 7/64 bit. Hopefully this will allow the autoplug to not require being fully tightened and to function correctly with the 7 1/2 Federal shot.

 

Hey TunnelRat, I did consider increasing the size of the holes to a bit size somewhere in between 3/32 and 7/64. The Home Depot and Lowes in my area do not carry those sizes. I checked with a Norther Tools in my area too and they only sell complete drill kits that contain those incremental sizes and the cheapest one available was over $100. The do not sell those incremental bits individually. The guy whom I spoke to said that my only option would be to try to order some off the internet from somewhere else. So basically, I tried to use your advice but that didn't work too well for me.

 

Thanks all...

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My drill index goes from 3/32 to 7/64 with nothing between them. Not all of us have invested in extensive bit kits. I mean, I don't see the point since I'd never use most of the bits anyway...

 

I understand...however, I didn't say anything about "investing in extensive bit kits". I simply suggested using one of the in between sizes, which are readily available and inexpensive. If you are going to drill out one or more ports, wouldn't it be better to do it gradually? Once you drill it out too much, there's no going back.

 

I understand but I've never in my life seen the six drill bits that you are referring to... Maybe our hardware stores here in Texas aren't as well stocked as they should be. What are these six sizes and where did you get them?

Hey TunnelRat, I did consider increasing the size of the holes to a bit size somewhere in between 3/32 and 7/64. The Home Depot and Lowes in my area do not carry those sizes. I checked with a Norther Tools in my area too and they only sell complete drill kits that contain those incremental sizes and the cheapest one available was over $100. The do not sell those incremental bits individually. The guy whom I spoke to said that my only option would be to try to order some off the internet from somewhere else. So basically, I tried to use your advice but that didn't work too well for me.

 

Thanks all...

 

Hey guys,

The drill bits in between 3/32" and 7/64" are #41 -#36, and there are 8 metric bits, 2.4mm - 2.75mm in 0.5mm increments. When I said readily available, I guess I should've said online, as these are not the sizes that are normally sold in retail stores like Home Depot. Drills and cutters.com will sell them individually, and these smaller sizes are pretty cheap, around $1.12 - $1.14 per bit. A #38 will be halfway between the two sizes you are currently using. I've worked in an industrial maintenance setting for several years, and managed to collect these sizes over time. Anyway, I hope maybe next time folks want to drill out their ports, they'll consider this option first. Folks don't seem to mind spending the money on gas plugs or other more expensive fixes, so a couple of bucks for a drill bit or two that may solve the problem isn't really asking too much....hey it's all good though. Best of luck on your projects!

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I am about to get my 2-port gun drilled by a professional gunsmith to open the ports. It requires the MD Arms plug to be at position 5 (wide open) to shoot slugs, this is with a glassbolt, MD Arms superpuck, and a low-brass spring.

 

Is a 3-port gun with 3/32 (.090) ports the ideal configuration?

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Hey guys. Home Despot and the internets are the wrong places to get drill bits. Every town has a decent industrial supply or five. They sell black drill bits in small sizes for something like $.80 ea, or less if you by them in envelopes of 10 or 20. IMO they are usually way better than the cobalt bits people on the forum here rave about. If you aren't sure where the good industrial supply is, ask a mechanic or machinist where he would go if he needs some bearings or bushings. It will probably be the same place.

 

4 port is usually considered to be better than 3. more smaller holes let in less crud than fewer huge holes. Some builders do 5 ports.

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It seems to me if the Autoplug is already set for low base ammo the problem is solved, as it is supposed to allow excess gas to pass.

 

Let me clarify.. My autoplug fully tightened and screwed all the way into the gas block was not 100% reliable with Federal 7 1/2 value packs. Plus, the ejection of the shells dropped them fairly close. That is the shell that I want to shoot in bulk..

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I am about to get my 2-port gun drilled by a professional gunsmith to open the ports. It requires the MD Arms plug to be at position 5 (wide open) to shoot slugs, this is with a glassbolt, MD Arms superpuck, and a low-brass spring.

 

Is a 3-port gun with 3/32 (.090) ports the ideal configuration?

 

I doubt that anyone can say what is the "ideal configuration". It's going to be different for every gun is seems. I can say that 3-ports of size 3/32 was NOT enough to shoot my desired low-brass loads, but your mileage may be completely different. Alternatively, I WILL share with you that hole sizes of 3/32 drilled to the correct angle from my experience does not cause so much crud in your gas block that you are required to clean at the range. Of course the gas block gets filthy, but 3/32 never caused so much that I had to dump the crude at the range.

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So they switch from fraction measurements to numerical values? I guess I was unclear in my request, I was wanting to know the fractional sizes of said drill bits. 128ths, 256ths???

 

not fractional at those sizes.....numbered. There are fractional, numbered, and lettered drills. Numbered are 1-80 which is .228-.0135, they decrease in diameter from .004 to .001 per number depending on the drills. Look up a drill index and it will tell you the diameter for the numbered drills, lettered drills etc.

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