Range report on my yugo Para project (1st snag solved) now a second snag

[BatBoy2 75]

Well I've hit my first bump,my rifle won't cycle correctly. I had a paper clip with me and it seemed to improve things a tad, but not much. As a side note, before shortening the barrel, the rifle cycled flawlessly.

Here are the next steps as I see it. Replace my old Yugo valve with a new SS valve and see if corrects the situation.

If a new valve doesn't fix the situation then, my next guess is that by shortening the barrel, I've reduced the gas pressure in the system. BTW- I'm 100% this is the issue and have my fingers crossed a new SS valve will tighten things up enough to fix things. If not, my next move is to enlarge the gas port.

Now here is where I need the boards help, if I have to enlarge the gas port hole, how much should I enlarge the hole by? I already know I'm going to have to remove the gas port assembly to get to gas port hole. So the 2 questions I have are:

How much should I enlarge the gas port hole by?

How do I drill out the gas port hole correctly, so I don't jack things up.

[mr.coinring]

I actually had a cycling issue with my yugo "para" when I bought it. The seller informed me that it worked fine until he cut it off.

I tried the paper clip fix with no luck....Then I opened the gas port and it got better....then I found that the recoil spring was binding on the retainer.

A combination of opening the gas port AND swapping out the recoil spring is what fixed mine.

When you take the gas tube off and look at the hole, it is at a 45 degree angle in the gas block and you will NOT need to remove the block to drill it larger. You will drill it right there in place being sure to not go into the bore too far and screw it up.

I cant remember what # drill bit hole it was to start with, but I only made it 2 or 3 #'s larger.

My drill bit set is numbered 1-40 and each one is almost identical to the next (very small increment changes)

I can check it out tomorrow and see what size it was that I made it if you would like. 

[BatBoy2 75]

I actually had a cycling issue with my yugo "para" when I bought it. The seller informed me that it worked fine until he cut it off.

I tried the paper clip fix with no luck....Then I opened the gas port and it got better....then I found that the recoil spring was binding on the retainer.

A combination of opening the gas port AND swapping out the recoil spring is what fixed mine.

When you take the gas tube off and look at the hole, it is at a 45 degree angle in the gas block and you will NOT need to remove the block to drill it larger. You will drill it right there in place being sure to not go into the bore too far and screw it up.

I cant remember what # drill bit hole it was to start with, but I only made it 2 or 3 #'s larger.

My drill bit set is numbered 1-40 and each one is almost identical to the next (very small increment changes)

I can check it out tomorrow and see what size it was that I made it if you would like.  

OK, no problem, looks like drilling is the answer. What about the gas port hole on the gas valve. Did you drill that out also?

[mr.coinring]

yep er didy..........I can get you a drill bit size tomorrow.

You might wanna get the valve first though, or maybe try a valve from another rifle.

I swapped my valve out with my other Yugo and it had zero effect.....that's why I didn't bother getting a new one.

Also take a really good look at your recoil spring retainer for any metal binding, and compare the length to a known good spring....maybe even swap that for a test also. Mine was a 1/2" longer than all the others. Guess it being a little longer made its diameter a tad bit smaller witch made it bind on the retainer just enough to barely stiffen the action......almost not even noticeable, but mainly in the last 25% of the rearward travel.

I think minor things will have more of an effect when cut down.   Have you fired the rifle before cutting it down? If so.....how was the cycling then?

[BatBoy2 75]

yep er didy..........I can get you a drill bit size tomorrow.

You might wanna get the valve first though, or maybe try a valve from another rifle.

I swapped my valve out with my other Yugo and it had zero effect.....that's why I didn't bother getting a new one.

Also take a really good look at your recoil spring retainer for any metal binding, and compare the length to a known good spring....maybe even swap that for a test also. Mine was a 1/2" longer than all the others. Guess it being a little longer made its diameter a tad bit smaller witch made it bind on the retainer just enough to barely stiffen the action......almost not even noticeable, but mainly in the last 25% of the rearward travel.

I think minor things will have more of an effect when cut down.   Have you fired the rifle before cutting it down? If so.....how was the cycling then?

It was cycling fine before the cut. After thinking about the situation and the advise you and prince50 have given me, I believe enlarging the gas port is going to be the ticket. I'll check the recoil spring against my others, just to make sure that's not an issue.

Just a FYI, I've already drilled the gas block and the gas valve out. I know, impulsive move; but that's how I roll.  I still would like to know what you used though.

[Reaper.308]

Hello all, first time poster, long time lurker 

BatBoy if when you testfire your sks after you have done your gas port modification can you please let me know what brand and size drill bit you used in order to make it work properly. I would much appreciate it.

Btw, what would happen if you drilled the gas port too large after cutting the bbl to 16.5"?

One more question and I am sure it has been answered but I have done a search many times to no avail. Where do you measure your bbl length from?

Thanks in advance and please give us some updates BatBoy 

[hogjon13]

Hello all, first time poster, long time lurker 

BatBoy if when you testfire your sks after you have done your gas port modification can you please let me know what brand and size drill bit you used in order to make it work properly. I would much appreciate it.

Btw, what would happen if you drilled the gas port too large after cutting the bbl to 16.5"?

One more question and I am sure it has been answered but I have done a search many times to no avail. Where do you measure your bbl length from?

Thanks in advance and please give us some updates BatBoy 

Measure from the breach face, (bolt closed).
Welcome to the boards.   
0/0

[mr.coinring]

Looks like I took it from about a size #28 to a #26.........with these types of drill bits, the larger you go the smaller the number.

A #26 drill bit measures .1455"

[Reaper.308]

Thanks guys 

Mrcoinring: you say those type of drill bits, but which type are ya talkin? I have craftsman and they are just by size, 1/8", 1/4", 1/2" etc.

[1mlt]

Thanks guys 

Mrcoinring: you say those type of drill bits, but which type are ya talkin? I have craftsman and they are just by size, 1/8", 1/4", 1/2" etc.

They are metric bits. You can buy one at a Ace hardware. Since you will only use it once or twice get a Vermont made bit. They cost less than Irwin and will do the job.
Marcus

[BatBoy2 75]

Thanks guys 

Mrcoinring: you say those type of drill bits, but which type are ya talkin? I have craftsman and they are just by size, 1/8", 1/4", 1/2" etc.

I used a cobalt 5/32" bit or 0.15625.

I would recommend that you the measure the max depth you're going to want to drill. You don't want to mess up the bore. I wrapped some tape around the spot on the drill bit as an ID on the maximum distance/depth I wanted to drill.

I'm happy to report that the problem has been fixed.

[mr.coinring]

Thanks guys  

Mrcoinring: you say those type of drill bits, but which type are ya talkin? I have craftsman and they are just by size, 1/8", 1/4", 1/2" etc.

I used a cobalt 5/32" bit or 0.15625.

I would recommend that you the measure the max depth you're going to want to drill. You don't want to mess up the bore. I wrapped some tape around the spot on the drill bit as an ID on the maximum distance/depth I wanted to drill.

I'm happy to report that the problem has been fixed.

WAAAAA HOOOOOOO!

5/32" bit or 0.15625  Close enough.  

Also want to mention that I was wrong about my #1-40 set.........Its #1-60 and its not meric     Its US number and letter gauge drill bit sizes.

This was copied from Wikipedia.
Number and letter gauge drill bits are still in common use in the U.S.. In the past, they were popular elsewhere, but now have been largely discarded in favour of metric sizes. A complication of using a gauge rather than a standard measurement of length is that the user always has to refer to a table of gauge sizes. For example, to drill a hole which is 10 thou (10 thousandth of an inch = .010) bigger than a 1/8 inch bolt, the user must first work out that 1/8 inch is 125 thou, so the hole size needed is 135 thou, and then must look up in a reference book which gauge drill bit has this diameter - a number 29.

Number drill bit gauge sizes are analogous to, but different from, American wire gauge. (See the conversion table below).

Number gauge is routinely used from size 80 (the smallest) to size 1 (the largest) followed by letter gauge size A (the smallest) to size Z (the largest). Number gauge is actually defined at least down to size 97, but these smaller sizes are rarely encountered. It happens that as the technology for making small drill bits and drilling small holes has become more available, metric measurements have become the norm.

Number and letter gauge drill bits are almost always twist drill bits. There is no particular reason why the gauge cannot be used to measure bits of other types, but the gauge covers a size range across which the twist drill bit is the most commonly used.

The gauge-to-diameter conversion does not follow a set formula, but rather was defined as a useful and practical measure. The graph shows how gauge diameters change with gauge. Each step along the horizontal axis is one gauge size. The step size between adjacent gauges is smaller for smaller gauges. This is appropriate, because the tolerance of the diameter of drilled holes is closer for smaller drill bits. The increment from one gauge to the next for a number 92 drill bit at 0.2 mm diameter is just 5%, compared to 10% for standard metric sizes.

[Reaper.308]

Wow, thanks gentleman. Much appreciated. Gotta love this place.

[BatBoy2 75]

Well I'm starting to believe I may need to re barrel my yugo para. I'll know more tomorrow when I have a chance to put some quality ammo through the barrel.

For now,I'll chalk it up to crappy yugo surplus ammo, but tomorrow I plan on putting 100 rounds of quality ammo down range to see what's going on.

I'm also going to ditch the williams peep sight and go back to the stock sights.

I'm still convinced the barrel is FUBARed, but just before I left the range I fired off twenty wolf FMJ rounds that grouped fairly well. This makes me want to give it a second go before I move on to a new barrel

So tomorrow, back to the factory sights and a new attempt at zero.

[mr.coinring]

I doubt its the barrel BatBoy.

Any way that you might have Darin's front post a little "off"

Also, apparently M08 has had to "whack" the rear sight leaf to correct this also.

see here.
http://www.sksboards.com/smf/index.php?topic=75049.0