gas port issues?

[Harter66]

I thought of just saying "so tell me about gasports mangling bullets and patches"then decided i'd better be more specific.

I'm working with a yugo sks 59/66 ,so says the bbl pencil. The bore is 316-305 with an equaly generous throat and chamber,readily excepting a 324-175r2 LEE naked and lubed. It also likes a 309-160 in 2 wraps of 20# copy paper ,I tried some with notebook paper but they were far worse,wet wrapped well over the ogive with a folded base . Uniform tails were not working out for me at this point . The bore was sad enough for me to give it some fire lapping and with the last loads it seemed like I was there,groups were coming in some so I stepped it up an shot some loads that were above and below a promising load,to see if it was comming in or going out . It seems to have been a fluke.

Now the bore over all looking from the breech and the flash hider/grenade launcher fittings it looks pretty shiney ,except for the last part past the gas port, gravel road. I saw a post else where that made me think that the port might be causing leading and my patch failure.

Thoughts?

[303Guy]

I would think that fire-lapping would 'debur' the gas port and solve that problem. Any idea what is causing that 'gravel road' up past the gas port? Rust or fouling?

[Harter66]

No guesses until I get some time to that gizmo off the end . It did lead a little with the naked boolits which was why I took the oppertunity to try some PP,I was confident that I had it pretty clean before I started lapping. I've launched 100 or so PPCBoos including those with compound on them . A fellow in the mil rifles mentioned having issues in rifles with ports in a land ,again I need to have a few minutes at home to check that out too.

303,
How far ahead is NZ of west coast US must be about 11-13 hrs. At first I thought dang he's up late/early,the it hit me nahh its just tomorrow mid morning. Kinda cool thinking you can answer a question 6 hours after I ask it ,before I even compose it.

[303Guy]

You folks are 7 hours behind GMT while we are 13 hours ahead. We're 20 hours ahead of you! I suppose with daylight savings in both our countries we will remain that way when you go into it and we go out of it. Or is it the other way around?

[Harter66]

We spring forward and fall back.

It is amusing in a way I'm headed to bed at 930 Monday night and your just off work Tuesday,presuming the atypical off at 5 sort of job.

[Harter66]

The gravel road seems to have been some sort of lead,copper,iron oxide amalgomation.I shot a few more laps with lite loads of Unique. Those 10 made a cute little 3" cluster . I had some other boolits,a 1 off 200 gr spire point,that over 6.0 of Unique plooped into about 4 inches and left the patches in 2 pieces.

The gas port is in the trailing as opposed to push edge of a land. Id say the gas port and piston leading is acceptable since it brushes off ,however the gas block/tube seal leaks and in the block/bbl corner there was enough to call a chunk of lead. Not totally unexpected given that I'm still learning the patch and looking for a good powder,primer,case,boolit,seating depth combo.

[303Guy]

I'm up at 5:40 and drive to work in the dark at this time of year. I love it! Daylight saving ends this coming weekend.:sad:

On the gas port and leading issue - I would have thought no lead or paper should make its way into the gas port. Well, maybe a little paper as that might be crumbling a bit. How far from the chamber is the gas port? That gravel road has to be cleared out. Fire-lapping might have been a bad suggestion as the build-up is uneven so the action of the grit would be uneven too. But then again the end result might be great. Mind you, I have taken out seriously ugly rust with just one shot and put a second one through just to debur any remaining pit edges. Mine are aggressive! But actually they remove a miniscule amount of metal. But, if there is a bur on the edge of that gas port it has to be removed. And if there is rust in the 'gravel road' then aggressive fire-lapping could be the answer. Remember that as long as that gravel road exists, any fire-lapping will remove surrounding steel before it manages to cut down through the 'gravel'. So maybe aggressive would be better?

Just a tip - should you consider my aggressive approach - the bit up front is the bore guiding piece while the bands further back fit the throat closely to keep that sucker concentric to the bore before the grinding paste bearing section hits! And the lapping bands are over groove diameter. It gets seated quite snugly without any neck sizing.

[Harter66]

The stuff past the port is gone now or is at least not visable and not showing up on cleaning patches. Somebody said" those sks/ak's have huge gas ports" I can stick a #30 drill in this 1 and have wiggle room. I suspect that any thing in the gas stream ,picked up from the bore or some other flash suspention (lack of a better discription), will exit there and stick to the block,piston and tube. For what its worth I'm not seeing any lead or paper impaction in the bbl extention at the muzzle,its a little over 1/2"(13mm?)and about 2 1/2 " deep beyond the muzzle.

The port is about 12" from the breach face 8" from the muzzle .

I did get some groups out of it but nothing really useable as of yet . this gives me an excuse to go shoot if nothing else. I intend to reslug the bore this week too.

Funny we have just movved to daylight savings ,I leave about 445 its dark all the way in for a few more weeks then there will be 5 miles straight into the sun that's just right to miss all the shades,posts,and mirrors,for a month or so.

[303Guy]

The stuff past the port is gone now ...That's great news. Friends of mine have an SKS and they clain it to be very accurate with Chinese ammo. I did see them shoot this thing at a fair distance and it was good indeed. Hopefuly yours will be good with PP. If that gasport interferes with the patches you may need to go to a faster powder to give less pressure at the gas port but that will mean no auto-loading - just a partial bolt movement.

[Harter66]

I enjoyed a success of sorts today . I went from wet wraps to dry. From WW to 1-20. I'm at a place where I am walking the line between backed out primers and belly buttons around the pin strike. Oh I did get a group out of that little tiny window 4 through a single hole just 3.5 boolits wide .......... no clue where 5th one went. I'm thinking a cut patch caused the flyer....er..dissappering boolit. Also I had a rather nice accumulation of patch oieces out in front of me mostly star-like bits still hooked at the base .

[nicholst55]

You folks are 7 hours behind GMT while we are 13 hours ahead. We're 20 hours ahead of you! I suppose with daylight savings in both our countries we will remain that way when you go into it and we go out of it. Or is it the other way around?

World Clock (http://www.timeanddate.com/worldclock/)

For the time-zone challenged among us, like me!