S-20 Gas Port Sizes and Range Report

[dinzag 31]

I have a 2002 19" S-20 that will eat anything. Initially it was sensitive to some cheap Federals, but after that it has been great. My buddy has a 2000 19" S-20 that prefers higher power loads. After over 300 rounds of shot, slugs & buckshot it still catches light load (2 1/2 dram) spent shells in the ejection port.

 

Specs on the two as well as others can be found here-->S-20 Receiver & Barrel Specifications

 

Rather than paying $7+/box for 2 3/4 dram ammo we decided to try opening up the ports. We tapped off the gas blocks of both and checked out the gas ports. Not surprising there was a difference.

 

My S-20's center-rear port measured 0.094" (3/32"). The two forward ports measured 0.078" (5/64") - one had a nasty burr in it. I cleaned it out.

 

Craig's S-20's ports were all the same, letting a 1/16" drill bit fit loosely, but a 5/64" wouldn't fit. I'm guessing they were 0.072"-0.075". We opened up all 3 to 0.078" (5/64") then opened the rear port to 0.094" (3/32") to match mine.

 

Yesterday he test fired and it went from about 30% failure to 6% out of 100 rounds fired. He used peter's #6 & #8 loads (2 1/2 dram). He wasn't happy so we opened all of the ports on his to 0.094" (3/32") & re-assembled.

 

Today we took both out and ran 100 rounds through each. His ran them 100% this time. All ejected about 6 to 8 feet out. A little further than mine was running. We didn't really pay attention the day before, but it got our attention today with the snow down. They had a nice spin on 'em and piled in roughly the same spot. He wanted to put it away and call it good, but I wanted to check out slugs on #1 setting. I couldn't really tell a difference between his & mine as far as recoil.

 

We then decided to bump fire some mags through them. We each did about 3 mags worth - hardly enough to get in the groove, but we found out something else. His ran great with only one FTE where I had 3 in one mag, a single and then 2 in the last one. We loaded up one more mag each and swapped guns. (it's always fun to swap!! ) He had 3 FTE with mine and I had zero with his. I'm sure a lot of it was due to "limp-wristing" it trying to bump fire, because from the shoulder it's fine. I decided I'm going to open my other 2 ports so all three are 0.094" - same as his.

 

That's what I found - sorry for the long post - deal with it!!!

As for removing the gas block, we used a 12" blunt end brass drift and a 2# hammer. Mine took about 15 good whacks and his took about 20. He did 2 before he realized he needed to take the pins out.

 

I'll get some pics up soon as we are doing handguard conversions on both of them.

[AegisDei 2]

Is it bad to open the ports too much? Or is it just that it might recoil worse and ultimately do some internal damage? Thanks for the info!

[dinzag 31]

Good question for Tony Rumore.

[IndyArms 10,186]

Regardless... I think it is a GOOD load of info... and range report....

 

Well done Dinzag!!!

 

 

[Cobra 76 two 2,677]

+1 on that!

Aegis it looks like we will get your shorty working after all!

[saiga20 0]

my results as of late

 

howdy I recently bought a Saiga 20 and like many people I was less than trilled with the performance using light target loads. So I've drilled the gas ports to .090" and took it out today to see the results. The gun is a modified saiga20 with a 18.25" barrel gas set on 2 removed the blue buffer.

 

I had excellent results with the Winchester load. I'd say 100% with the gun shouldered and 90% bump firing

 

Win superX high brass game load 2-3/4inches 2-3/4" dr eq 1oz. #6 lead shot bought 4 boxes at a gun show for 3.95 each box of 25

 

The Remington loads also worked 100% when fired from the shoulder and about 50% bump firing

 

Rem game loads 2-3/4 1225 vel 7/8oz. #8shot gl208 bought at a local Bi-mart for 3.99 per box of 25

 

 

 

the Estate cartridges would only cycle about 75 percent of the time with. About half of the malfunctions are FTF and the other half FTE

 

Estate cartridge super sport competition target load 2-3/4" 7/8oz. #8 shot 2-1/2" dram eq I also bought these for about 4.00$ at Local Bi-mart

 

 

I will add more as I try different loads

 

edit cus I had the wrong gas setting

Edited March 6, 2006 by Ikilludie

[dinzag 31]

Thanks for the info - those Rems are 2 1/2 dram I believe. The Wins were 2 3/4 dram and the estates are 2 1/2 dram. The Estates I use are Heavy Game - with a 2 1/2 dram load.

 

Try the Estates on #2 and see how they do. I suspect you will see an improvement over the #1 setting. Thanks for your range report! Also, was your barrel cut back to 18.25"? Most of the ones I've seen have been a touch longer - in the 19" range.

[saiga20 0]

Thanks for the info - those Rems are 2 1/2 dram I believe. The Wins were 2 3/4 dram and the estates are 2 1/2 dram. The Estates I use are Heavy Game - with a 2 1/2 dram load.

 

Try the Estates on #2 and see how they do. I suspect you will see an improvement over the #1 setting. Thanks for your range report! Also, was your barrel cut back to 18.25"? Most of the ones I've seen have been a touch longer - in the 19" range.

 

Sorry I miss typed I was on gas setting #2. Also the barrel was cut down to 18" by the pervious owner

[dinzag 31]

O.K. that was what I figured - thanks for the correction.

 

Would you say it was improved over the previous gas port sizes? Would you happen to know what sizes the original holes were? Were they all three the same size?

 

I'd suggest opening the ports up a tad more. Your barrel is a tad shorter and your holes are a tad smaller than our setups. That or check with Cobra & AegisDei about their recoil spring conclusions. They put a lot of time into it.

 

Do you know approx how many rounds have been run through it to date? If it hasn't had many, maybe a good break-in with heavy loads will help.

 

I think the problem with bumpfiring the S-20 & S-12's from the hip is the recoil. The gun is moving in the same direction the empty casing is, but with more force than the rifles. We plan on bumping from the shoulder (or trying to) on Sunday.

 

Edited March 8, 2006 by dinzag

[saiga20 0]

I would say that opening the gas ports is a big improvement. The holes were about .07" and all the same. I'm not sure how many round the previous owner put though the gun. It didn't look like that many from the wear and tear on the gun but its hard to say. I got 200 slugs with the gun when I bought it so I've been shooting 20 or so ever time I take her out. I'll try out a new load or two every time I take her out and post the results. If I open up the ports any more I will also let everyone know.

 

 

for anyone who is considering drilling out the ports its really not hard. hammer,punch and a brass or soft metal to act as a drift. the a drill and drill bit of the size your are looking for. I would advise that you get a good high speed steel bit and not something from harbor freight. be careful to realign every thing when reassembling and you good to go.

 

this tread needs some pics so here

[dinzag 31]

Nice pile of hardware & 4x4! Thanks for the info too!