G O B 3,516 Posted May 2, 2005 Report Share Posted May 2, 2005 For very short barells, there are only a few variables available for tuning. 1. The standard bolt carrier for AK's has the spring stop in the carrier (the end towards the muzzle) much deeper than the S-12. Due to the cutout for ejecting huge 12ga. shells, there is only so much we can do there, the stop can be moved to the rear (more tension) with a pin, but cannot be moved towards the muzzle(less tension) For the .410 crowd, this stop is just a pin through the carrier and is easy to manipulate for tuning 2. This is the easiest. The gas piston that is screwed into the piston carrier can be screwed forwards (towards the barell) with the "blind plug" out you can see when the max adjustment is made, the gasport cannot be occluded. If more adjustment is needed the regulator piston can be shortened. (I would have spare parts before getting drastic) The "blind plug" may need to be replaced with a custom made piece, a shorter plug without the 'slant cut' will allow the regulator piston to be turned down in diamiter to allow it to come forward of the gas port without blocking it. The increase in stroke should be helpfull. 3. Mass. The boltcarrier/piston assy looks to be as light as it can be made, but any mass that can be safely eliminated will help. Try leaving out the side cover that is trapped in the spring. 4. Dampening. The more energy that is absorbed, the less that is available to cycle the action. Try no buffer, or a black buffer. Try weighting the stock. Try different return springs. Try spacers in the rear of the return spring, on the rod. I personally don't care for short barells, even for HD I like 19" so this is just an intellectual exercise for me, but I would love to know haw these variables affect the function. Who knows, I just might get a "wild hair". G O B Quote Link to post Share on other sites
6500rpm 670 Posted May 2, 2005 Report Share Posted May 2, 2005 Does anyone have an idea of what you can get away with in terms of shortening a barrel without causing problems with the gun cycling? I plan on taking down a 22" IC version to around 19" and having it threaded for an internal choke. I have the ability to open the ports up, but would rather not if 19" is safe. I'm a little confused about porting the chamber being hack, wouldn't you overcome some of the pressure woes by adding additional volume? Most of the rifles named have the ability to run very fast cycle rates and have much higher pressures generated. The 12 to me would be a little different. I'm just asking to learn, not to be a smart ass, this isn't my area. It doesn't look like there's much you can do with the Saiga to change timing/dwell which only seems to leave volume, or pressure by changing loads (custom reloads)? Quote Link to post Share on other sites
pedal2alloy 206 Posted May 2, 2005 Report Share Posted May 2, 2005 There are others here with more experience, but I think that any cutting down of the barrel will require some additional tuning to get back to "stock" reliability. All of the various componants had to be balanced out when the gun was developed so any changes will require tuning of something. With regard to GOB's tutorial which is great, I only have enough knowledge to comment on 2 things. 1) Wouldn't it be possible to create a different gas valve similar to a FAL which instead of having 2 settings, it had something like 10 settings? Wouldn't that really kick ass? 2) My instinct on fooling with the return spring is not to do it. The reason is that it needs a lot of strength on the return stroke to strip off a round especially on an 8 round mag not to mention a 10 round mag that people are developing. In fact, I think that is why they stopped at 8, because the higher the mag capacity, the stronger the mag spring needs to be to lift the rounds, and the harder it is for the bolt to strip off a round. I would also be curious if anyone has measured the size of the gas ports on a factory 18" barrel. (??) Quote Link to post Share on other sites
johnnymceldoo 0 Posted May 26, 2005 Author Report Share Posted May 26, 2005 *bump* Quote Link to post Share on other sites
CGuns 3 Posted May 26, 2005 Report Share Posted May 26, 2005 Bvamp...Gas port tool? Rezeroing? Can you expand on this... <{POST_SNAPBACK}> Yep! X2 I am lost.... Thanks, CGuns Quote Link to post Share on other sites
steve467 0 Posted July 25, 2005 Report Share Posted July 25, 2005 (edited) Johnny I'm in the middle of trying to enlarge my ports too. Can I trouble you to repost the pics at the beginning of this thread. I'm having a hell of a time getting the gas block off. I've got the pins out but can't seem to get it to move. I'm thinking about cutting the gas tube to get it out of the way so I can press the gas block, but would appreciate any tips before I do that. Thanks, Steve Edited July 25, 2005 by steve467 Quote Link to post Share on other sites
twinhairdryers 2 Posted July 25, 2005 Report Share Posted July 25, 2005 I was in the same boat, spent over an hour trying to knock that block down and was worried I was just going to damage the gun in the process before giving up. It seemed like such an easy thing to do to drill these gas holes a bit larger, then turned into a very difficult task. Johnny I'm in the middle of trying to enlarge my ports too. Can I trouble you to repost the pics at the beginning of this thread. I'm having a hell of a time getting the gas block off. I've got the pins out but can't seem to get it to move. I'm thinking about cutting the gas tube to get it out of the way so I can press the gas block, but would appreciate any tips before I do that. Thanks, Steve <{POST_SNAPBACK}> Quote Link to post Share on other sites
steve467 0 Posted July 26, 2005 Report Share Posted July 26, 2005 Quote Link to post Share on other sites
twinhairdryers 2 Posted July 26, 2005 Report Share Posted July 26, 2005 Gave up on the gas block removal. I ended up cutting 3 links off my recoil spring, and I make sure the my gas chamber is super clean and lightly lubed. The misfeeds aren't a huge problem for my cutdown barrel, just an annoyance at times. I was in the same boat, spent over an hour trying to knock that block down and was worried I was just going to damage the gun in the process before giving up. It seemed like such an easy thing to do to drill these gas holes a bit larger, then turned into a very difficult task. Johnny I'm in the middle of trying to enlarge my ports too. Can I trouble you to repost the pics at the beginning of this thread. I'm having a hell of a time getting the gas block off. I've got the pins out but can't seem to get it to move. I'm thinking about cutting the gas tube to get it out of the way so I can press the gas block, but would appreciate any tips before I do that. Thanks, Steve <{POST_SNAPBACK}> <{POST_SNAPBACK}> So what did you end up doing? <{POST_SNAPBACK}> Quote Link to post Share on other sites
USP40 1 Posted July 30, 2005 Report Share Posted July 30, 2005 I cut my bbl down to 19" and had problem with light load will not cycle the rds. I emailed johnnymceldoo to ask about his post . He was very nice and helpful. I took the gas block off enlarge the gas ports to .900 but didn't have a chance to take it out for testing until today Well guys my Saiga now ran 100% on the light load I even bump firing it. Just want to tell Johnnymceldoo THANKS MAN. Quote Link to post Share on other sites
steve467 0 Posted July 31, 2005 Report Share Posted July 31, 2005 I cut my bbl down to 19" and had problem with light load will not cycle the rds. I emailed johnnymceldoo to ask about his post . He was very nice and helpful. I took the gas block off enlarge the gas ports to .900 but didn't have a chance to take it out for testing until today Well guys my Saiga now ran 100% on the light load I even bump firing it. Just want to tell Johnnymceldoo THANKS MAN. <{POST_SNAPBACK}> I'm stuck on the gas block right now. There's really no good place to bang on it and hardly enough of an edge to press it off. I'm going to have to figure out how to make a jig to press it I guess...unless someone here has a better idea. Steve Quote Link to post Share on other sites
USMC_LB 4 Posted July 31, 2005 Report Share Posted July 31, 2005 Just be patient... we need to get johnnymceldoo in here to answer your questions. Dont do anything you cannot un-do... LB Quote Link to post Share on other sites
USP40 1 Posted July 31, 2005 Report Share Posted July 31, 2005 After I took the hand guard off and took the pin out of the gas block it only took 10-15 minutes to take the gas block off. here what I used to do it with . I used a piece of flat metal taht connect the garage door opener rail to the garage door to hit the gas block . I turned the S12 upside down and laid the metal bar on the bbl and whack the gas block it wrked for me but you might want to tape that metal bar with black tape so it would mess up your bbl finish or gas block . You can try it but don't bitch at if it doesn't work for you. The main thing is you have to hit the gas block at the base of it by sliding( whack) the flat metal piece on the bbl. The gas block came off easy I was happy . Quote Link to post Share on other sites
steve467 0 Posted July 31, 2005 Report Share Posted July 31, 2005 (edited) Well I was inspired by USP40's post and used a flat piece of metal as a sort of bucking bar. Worked great, I was surprised to see the rear sight housing wasn't attached to the barrel like on AKs. In the pics below you might notice I managed to take off the bolt on the top of the gas block for the sight. That was an error caused by trying to use it a a grip to press the barrel off..duh. It didn't take much force at all and that bolt popped out. Of course I'll have to get it back in there or weld up the hole to get the gas system to work right. Ok it's drilling time. My goal is light loads function with no problem on setting #2, and I have the three-port config. After going over this thread looks like the best starting point is .09 (?). Edited July 31, 2005 by steve467 Quote Link to post Share on other sites
USP40 1 Posted July 31, 2005 Report Share Posted July 31, 2005 Steve I enlarged mine to .095 worked great. BECAREFUL when you do the drilling use good high speed bit and take your time , you could drill the holes too big and brake that triangle . Good luck man Quote Link to post Share on other sites
johnnymceldoo 0 Posted August 2, 2005 Author Report Share Posted August 2, 2005 Sorry guys but I pretty much stopped coming here after my shotty was stolen. Kinda dont like to think about it if you know what I mean. Yes that block is sort of tight around the barrel. I heated mine about 300-400 F and tilted the barrel downward against a thick wood table and took a soft piece of metal and smacked the block off. I think it took about an inch or so of tight movement before coming off. Then I chucked the barrel in the lathe and polished that area so it would go on easier. I did ding the block up a tad but I was refinishing anyways so I wasnt worried about small dings. Hope that helps some of you and Im glad to see some of you had good success so far in this process. Quote Link to post Share on other sites
detpat 0 Posted August 2, 2005 Report Share Posted August 2, 2005 Sorry guys but I pretty much stopped coming here after my shotty was stolen. Kinda dont like to think about it if you know what I mean. i got an s20 i could let you fondle, uhhh i mean use until you get another, if ya want. it's not the same but at least it will keep you warm at night. pat Quote Link to post Share on other sites
johnnymceldoo 0 Posted August 2, 2005 Author Report Share Posted August 2, 2005 Sorry guys but I pretty much stopped coming here after my shotty was stolen. Kinda dont like to think about it if you know what I mean. i got an s20 i could let you fondle, uhhh i mean use until you get another, if ya want. it's not the same but at least it will keep you warm at night. pat <{POST_SNAPBACK}> Thats kind of you offer. I thought about buying an 870 or something but Its not the same. Quote Link to post Share on other sites
USP40 1 Posted August 2, 2005 Report Share Posted August 2, 2005 sorry to hear about your S12 johnnymceldoo Quote Link to post Share on other sites
detpat 0 Posted August 5, 2005 Report Share Posted August 5, 2005 iaaawwwrrright, i'll drive up and let you touch, maybe even hold my s12, but ya gotta give it RIGHT BACK. pat Quote Link to post Share on other sites
steve467 0 Posted August 13, 2005 Report Share Posted August 13, 2005 (edited) Got this back together and took it to the range today. I bored out all three gas ports with a #42 (.093) drill bit and it functioned flawlessly today with 2 3/4" 1oz #8 shot on the #2 gas setting. Seems like less recoil if you can believe that. I'm probably losing some muzzle velocity with the bigger gas ports but this is my 3-gun shotgun so no matter. If I want it to hit harder I could just go with 3" magnums...heheh. Thanks to everybody who contributed to this thread, I probably wouldn't have tried this modification without it. Steve Edited August 13, 2005 by steve467 Quote Link to post Share on other sites
USP40 1 Posted August 14, 2005 Report Share Posted August 14, 2005 Got this back together and took it to the range today. I bored out all three gas ports with a #42 (.093) drill bit and it functioned flawlessly today with 2 3/4" 1oz #8 shot on the #2 gas setting. Seems like less recoil if you can believe that. I'm probably losing some muzzle velocity with the bigger gas ports but this is my 3-gun shotgun so no matter. If I want it to hit harder I could just go with 3" magnums...heheh. Thanks to everybody who contributed to this thread, I probably wouldn't have tried this modification without it. Steve <{POST_SNAPBACK}> Quote Link to post Share on other sites
BS1066 0 Posted August 28, 2005 Report Share Posted August 28, 2005 I made a jig to press the gas block off my Saiga 12. If there's interest I'll post more pics and shop drawings you'd need to make one. Butch... Quote Link to post Share on other sites
stimpsonjcat 0 Posted August 29, 2005 Report Share Posted August 29, 2005 There are others here with more experience, but I think that any cutting down of the barrel will require some additional tuning to get back to "stock" reliability. This was not the case for me. I whacked 4" off my 22+" Saiga 12 and it didn't miss a beat with 1-1/8 oz shot. 1) Wouldn't it be possible to create a different gas valve similar to a FAL which instead of having 2 settings, it had something like 10 settings? Wouldn't that really kick ass? This was my backup plan if the shotgun had misbehaved. This would be VERY easy to do with a dremel...just grind out slots like the two already on the plug at various positions between 1 and 2. I may even still do this as it seems like such a simple fix. It's not really like a FAL (we are changing how much barrell pressure gets to the spring, not how much gets bled off) but it has the same effect as a regulator. Anyone whose cut down cycles on 2 but not on 1 with light loads should consider this option IMHO. Quote Link to post Share on other sites
Rusty 0 Posted August 29, 2005 Report Share Posted August 29, 2005 I made a jig to press the gas block off my Saiga 12. If there's interest I'll post more pics and shop drawings you'd need to make one. Butch... <{POST_SNAPBACK}> I'm interested. Quote Link to post Share on other sites
mikey1 0 Posted August 29, 2005 Report Share Posted August 29, 2005 (edited) Fellow Saiga12 owners...I don't feel the gas system is ALL the problem?...you might want too try this before drilling?... My S20 (see "jams" on the 20 site) WAS bad!!! on LOW VEL ammo... NOT ANY MORE. Simply sustitute a COLT .45 spring for the front Saiga spring (on a S12 a slightly heavyer spring,say 13#,14# may be better??). You will have $5 invested and no non reversible actions taken. I don't shoot my S12 much, ....AWATTING THE S12 MAG "GOD" TO APPEAR AND FEED THE HUNGRY!!!mikey1 Edited August 29, 2005 by mikey1 Quote Link to post Share on other sites
G O B 3,516 Posted August 30, 2005 Report Share Posted August 30, 2005 Go Mikey! Good find. Th Saiga springs seem to vary in stiffness. It's always good to find non "undoable" things to try for tuning. G O B Quote Link to post Share on other sites
Cobra 76 two 2,677 Posted September 13, 2005 Report Share Posted September 13, 2005 I was comparing the ports on my S-12s yesterday and noticed on my 01' model 22"er there are 4 gas ports in a diamond shape rather than 3 in a triangle like all the rest I've seen. My other ones are 19"ers. Is this normal for the 22" versions? Quote Link to post Share on other sites
JumiKuula 1 Posted September 13, 2005 Report Share Posted September 13, 2005 (edited) I was comparing the ports on my S-12s yesterday and noticed on my 01' model 22"er there are 4 gas ports in a diamond shape rather than 3 in a triangle like all the rest I've seen. My other ones are 19"ers. Is this normal for the 22" versions? <{POST_SNAPBACK}> Longer barrels usually have only three holes but shorter ones have four. ShitBird lost 30cm of its barrel and so it was modified to "four-hole set-up" as one can see in toiminta-ampujat.net BTW those new holes are 2.2mm and ShitBird started to cycle with 24g for the first time of its life... -JumiKuula aka JamShot Edited September 13, 2005 by JumiKuula Quote Link to post Share on other sites
M15A4spr 0 Posted September 14, 2005 Report Share Posted September 14, 2005 On the first post in the thread, the picts are busted Quote Link to post Share on other sites
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