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.410 might be possible

9K views 63 replies 7 participants last post by  TRX 
#1 ·
Saiga .410s aren't $149 any more, and you'd have to find one, pay the FFL fees at both ends, plus shipping, and then you'd still have to buy all the parts and do all the work to convert it to AK configuration.

Building a parts kit into a pistol is legal. Same should apply to building a kit into a shotgun.

Kits are back down to $119 right at the moment.

Doing some preliminary doodling, it looks like it should be possible to build a standard-length AK in .410, bypassing the whole "buy and Saiga and convert it" thing.

A .410 conversion should be roughly similar to a .308 conversion. A .410 shell will fit in a .308 magazine. Do the usual mods to fit a .308 mag.

Unlike a regular cartridge, a shotshell is longer after it's fired. This should not be a problem.

The Saiga 12 and 20 gauge rifles use a two-piece bolt head, but the .410 is one-piece. I figured the two-piece bolts were for ease of manufacture or to make extraction easier, but Saiga figured the .410 didn't need it.

The .410 rim diameter is .524", a 54R is .567", so there's room to open up a standard AK bolt to .410 size.

Numrich has 3" chambered .410 barrels for $50-ish. As a wild guess, I'd expect they'd be thinner than AK barrels and would require bushings at the tenon and to mount the RSB, GB, and FSB.

Lore has it that Saiga went to the new gas block with the oversize floating piston to get sufficient zip to cycle the action with low-pressure shotgun shells. Given the AK's flexibility in handling lower pressure metallic cartridges, I'd give the stock configuration a try before getting fancy. Then I'd open up the gas port a bit, space the gas piston to put it deeper into the gas block, and maybe ream out the gas block as far as practical and sleeve the piston. If none of those worked, a homemade gas block with a Saiga-sized piston ought to work. The floating tappet shouldn't be necessary.

If you started with a Yugo gas block, you could make it adjustable by modifying the gas shutoff.

Looking at pictures (I've never had the opportunity to handle a Saiga in the metal) it looks like the front trunnion is designed with some kind of guide ribs to help the shotshell go into the breech straight. The bolt also has fingers going forward, supposedly for that purpose. A shotshell's flat front means it has little room for deviation from the barrel centerline, whereas a pointy rifle bullet just has to hit the hole somewhere.

Again, I'd try it and see how things worked before over-planning things. Put a mark on the top of a shell with a felt tip, use that as a clock to see where the end of the shell hits the breech face. I can think of half a dozen ways to add guides or fillers to direct the cartridge if needed.
 
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#28 ·
They don't seem to exist in my local area. And once I paid an FFL and shipping to get one here, I'd still have to convert it.

$120 Romy underfolder kit, $35 AK-Builder flat, $25 Numrich .410 barrel, and the parts box is cheaper than I could get a .410 Saiga to my door... and then I'd be out about the same time and money to convert it to AK configuration.

I kind of have my heart set on a double-underfolder .410 now.

Other than that, "just because" ought to cover it!
 
#29 ·
for me it will be for my swith barrel build and I will only need to do the barrel. that and I have a few kits i bought cheap back in the day. 119 barrel less kit and a cheap barrel and it can be done for less than $150 total on a flat. I dont think they need compliance part on a shot gun or am I wrong???? I thought it was just on assult rifles I havent really thought about it.?????????

Dont for get that after you buy a Sagia you need to convert it if you want a pistol grip. and that is going to cost. then a Saiga needs expensive mags. I paid $175 for mine before obama and I need to but a pair of mags that will cost close to $80. If I can make a $2 g2 mag work then I can have lots of mags cheap.

the mag is however the secret to the Sagai working and its differant than any oter AK in how it feeds when the bolt is back the round hits the upper shroud before it ever starts to leave the mag. it a a reaally steep angle in the factory mag.

the dust cover is differant as well as the recoil assembly. the spring has a short rod in it and the spring does not go all the way forward inside the carrier and the buttion has a lock in itthat has to be pressed to remove the cover. there is also a cool sheild on the spring that covers the enlarged ejection port in the cover. I may coppy the sheold on my 308 length switch barrel build to keep dust and snow out.

here is a few pics the bottom of the carrier has a grove cut into it in the front also. and not the shell position when the mag isinstalled it is up against the shroud
 

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#30 ·
I found a 28 guage blank cheap Im still trying to figure out a rimless version for sporting clays I likely can take brass shells and rebate the rim. the case minus rim will almost clear the lugs a few thousands renoved and it will. I would only need a two rond mag for clays as that is all you shoot at one time. so I could actualy get away with a one round mag and load one in the pipe. 50 rounds of brass shells will last a long long time if i dont loose them. a small shell catcher will be needed to hold a couple shells per round. I must have a AK sporting clays gun in 28 guage.

I suspose I could buy a 20 guage and just use that but thats no fun besides who else would have a AK 28 Guage?????? LOL and I can hunt deer with a 28 guage cant with a 410 in this state. My son will need a small bore slug gun in my zone as he cant use pistol untill he is 18.
 
#31 ·
after looking at a misc Saiga trunion (not sure of its oigin I noticed the lugs are wider apart than a saiga 410 and more like a 308 (its not bulged and has a 22mm bore) I can almost get a 28 guage shell through there as is. It would be alot of work to get this to work with a standard bolt

the bolt is almost going to need to be long like factory on a 410 to be able to get this to feed with a shroud.

also note how the factory bolt head is reduced in the extended section so it will fit between the upper and lower guides /shrouds and rotate. Im thinking a bolt head extension pinned in, might be the ticket like on a 20 guage. it might be the trick to get a 28 guage to work as well
 
#32 ·
Midway sells 32 gauge shells. Considering how oddball it is, I thought the price was surprisingly reasonable.

If I remember Ed Hubel's 12gaFH thread on Accurate Reloading correctly, he got a ruling from the ATF on his .720 caliber rifles. The ATF said that even if the barrel was rifled and he was shooting blown-out BMG in it, if it would still accept a standard shotshell, it was still a shotgun as far as they were concerned.

Of course, shotshells have tiny rims, and with enough extractor hook travel, there's no reason you couldn't shoot a rimless brass shell, as long as the rifle could still shoot a standard shotshell. At least, that's how I understood the thread. It's something like 65 pages long now...

I have a 4140 bar cut up to make bolts from. Depending on how the feed issues work out, I could always make a Saiga-length bolt if I had to. I'd like to do it without going that far, if possible, so others could duplicate it without a lathe and heat treating a bolt.
 
#35 ·
Looks like, other than the kit, the most expensive part of this build will be the bayonet. eBay and Gunbroker prices reflect the average selling price I found on various fora - $100 to $125! Yow!

On the other hand, Polytech's web site has brand new underfolder bayonets for $75... sometimes I wonder how people set prices on things.
 
#36 ·
The .410 barrel showed up today. It says "NEW HAVEN BY MOSSBERG MODEL 283T - .410 GA. - FULL CHOKE 2 1/2 AND 3 IN SHELLS - NORTH HAVEN, CONNECTICUT - MADE IN USA" on it. Quite a lot, for a small barrel...

The breech end is threaded. The picture at Numrich showed dovetails cut for the pump bits, and fingers going back over the breech. This is just threaded, no dovetails, which is good. I suspect the picture was generic.

Interestingly, the threaded tenon is small enough that when I make a bushing to press it into the AK trunnion, the barrel pin shouldn't intersect the threads.

I think most of the "finger" function, if needed, could be taken care of by an extension to the rear sight block.

The barrel is .812 where the RSB goes; the RSB ID is .790. It would be easiest to turn the barrel down to accept the RSB. The barrel is tapered where the gas block goes, .625-ish. The gas block is .595 ID.

SAAMI pressure for the .410 is 13,500, so shaving .022-.025 from the barrel diameter shouldn't hurt anything.
 
#37 ·
Hmm. One barrel says "New Haven" and the tenon is .725x24tpi. The other says "Western Auto" and the tenon is .715x24tpi. Otherwise the barrels are identical.

23/32 is .7188", or 8.256mm. Close enough for 8.25mm, except for the thread pitch. Weird.

I was going to order a tap, but I guess I could pin the barrel to the spacer sleeve. It's an AK, after all... My internal threading skills are shaky, and I'd just as soon avoid that if possible.
 
#38 ·
if you had a reamer and you could cut the end down and thread the .812 secton to
7/8-14 thread and then bore out a 22mm trunion slightly and thread the trunion. and then you would not need a pin. the chamber can be done on a lathe with out a reamer BTW. in the end it likely would be about the same work as doing a bushing. you could do a threaded rifle barrel in some thing 243 or any 308 length shell and have a two barrel set. :) Im working on my switch barrel reciver now.

I will have some bent blanks that are 1/2" longer possably for sale very soon in .O45and .060 4130 steel, they wont have mag demples so a wide G3 mag will fit. Ill have the longer rails also.
 
#39 ·
put the tap in a drill press to keep it straight and clamp your work down before you drill or bore to cut nice square internal threads. if something like a bushing is being done then turn it in a lathe put the tap chuck in the tail stock and then turn the chuck back and forth by hand. dont tightn the tail stock so you can apply forward pressure. if the treads are externial and your not cutting them with a bit they make die holders that will fir the tail stock. I have been doing muzzel treads like that and they are reasonably true and work fine for a muzzel attachment etc.
 
#41 ·
It's good enough for Kalashnikov, it's good enough for me...
His design had a threaded barrel. Im guessing it was bean counters and politicains that made it a stamped, pinned & riveted ugly monster it is today LOL.

Im hoping to thread a trunion this week to get a idea of how hard its really going to be. i ahve made up alignment guagesa nd go no go guages and am working on a way to turn my mills spindle by hand with a tap in it. I spent yesterday cutting out blanks form 4130 plate and designing a G3 mag well and working on ways to keep the mag in. I have a super cool idea. Ill may be doing some extral long in the front bent blanks inthe near future that might be for sale if there is intreast. I also have the metal bent for the rails so the ejector wont have to be welded in on a standard rail.
 
#42 ·
My lathe is a 1950s Atlas 10x60. The Atlas design doubles the leadscrew as the power feed screw. It hangs right out in the open, for rust and swarf. By the time I got the lathe the screw was noticeably worn; despite my best attempts to preserve it, it's now worn to almost a V thread.

I could thread something long enough to hold in the steady rest, over an unworn portion of the screw, but it's all enough of a hassle I'd as soon avoid it.
 
#43 ·
So, I'd ordered a nice Romy underfolder flat from AK-Builder for $30, and a couple of Tapco flats from DPH for $15 each. I pulled the Tapco flats out of their bags and the outer sides have a very coarse belt-sanded finish, not at all like the one I bought a year ago.

So I set the first one up to bend... and bent it wrong.

[unprintable: deleted]

The top rails weren't completely bent at the front, and I'd measured across the outside. That made the sides .020" different in height.

My fault for not triple-checking. I measured to the inside of the (partial) bend on the second one, and got it right.

The AK-Builder flat, by comparison, is a whole different thing. Nice and smooth. No locating pin holes, so I had to drive my roll pins down flush. Stepped top rail! And properly bent and trimmed up front, no Dremel work needed to get the flat to fit into the slots in the trunnion. Beveled sides at the ejection area.

AK-Builder's equivalent (non underfolder) flat is $20. Next time I'll pay the extra $5, even if they don't come with lower rails.
 
#46 ·
if your building from a blank you likely could heat them and flatten them out some. On a tapco I dont think they will clear.

Im going this route on on my conversion builds its 1/2" longer than standard in the front a lots in the rear but will be cut to normal in the back.
4130 steel this one .045
 

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#48 ·
Bending the Tapco flat -

It's a variant of 555th's fixture. The flat bolts between two shoes, then some fine thread 3/8" rod pulls it through.

The miscellaneous holes are because the angle iron is recycled from a previous project.
 

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#49 ·
I set the barrel up with the breech at the tailstock end so I could turn the threads down. There's a radius on the end of the tool to prevent a stress riser at the end of the cut.

Flip the barrel over, cut the step for the RSB. There was no way the Romanian bits were going to work, but the Chinese bits were all bigger. I only had to turn .020 or so off the barrel for the RSB.

Moving up to the handguard retainer area, I discovered the barrel wasn't straight, though it looked okay sighting down the bore. It was also out-of-round. The kicker is, it appeared to be rolled and welded, like muffler pipe! There was a dark line on the inside that I thought might have been rust from condensation. There's a definite lump on the outside, though, and you can see some imperfections where it was welded. I know Ford uses welded brake lines in their cars, and welded tubing does fine for hydraulic cylinders, and the .410 isn't a high pressure cartridge, but it was a bit creepy just the same.

The handguard retainer bit cleared up. I repositioned the barrel to reduce the unsupported area. When I bought the lathe, it came with TWO steady rests. Unfortunately, I just discovered one is apparently for a South Bend, or at least a 10" lathe with a single pyramidal way. The other fits the Atlas, but it's for a 12" lathe. <sigh> I sharpened the tool and made teeny tiny cuts, holding onto the barrel with my hand to damp the vibration.

Unfortunately the combination of warp and out-of-round on the gas block area made it impossible to turn concentric. After cogitating a while, I dressed the high spots with a file, then filed it down to the right size. It's a bit out of round, but it shouldn't affect the press fit.

I'll have to cut the barrel for the FSB later.

Fortunately, the Chinese parts were almost perfect. Even opening up the Romanian RSB and GB as far as they would go, I don't think I would have had enough barrel thickness to be safe. It would have required custom parts, or cutting and welding tubes to the Romanian parts.
 

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#50 ·
I have two Romanian handguard retainers and an AMD-65 retainer. They have keys on the sides to keep the retainers from twisting on the barrel.

The Chinese retainer is from a 1966 milled military rifle. Besides being larger in diameter, it has no keys; it's retained only by the flip lever and shaft.
 
#51 ·
M-14 magazine with 3" .410s in it.

The spring is pretty stout; the top shell has been in the magazine for a couple of days. You can see where it has bent under the load.

I'll have to get some music wire and wind a weaker spring, and balance spring tension vs. feeding later.
 

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#52 ·
The bolt is from one of the Romanian parts kits I bought. The pins just pushed out by hand when I took it apart.

The boring tool is a ground-down 1/2" end mill. I made the toolpost years ago; it has a slot for a 3/8" tool at the correct height, and a 1/2" hole for a boring bar on center.

The metal cut easily enough, and the sharp cutter didn't care about the interrupted cut. The Romanians put a great big dirt groove around the perimeter of the bolt face, which makes it look funny when the OD is opened up. I'm not sure what it will do to the soft shotgun shells when fired, but from comments on Saiga-12.com some Saigas are like that and it doesn't hurt anything.

I haven't recut the extractor yet. It sits at an angle, and the rim on the shotgun shell is round and not as tall as a 7.62x39, so I want to grok it in fullness before cutting.

I managed to salvage the mis-bent Tapco flat. I adjusted the hole positions with a diamond bit, then cut off the screws to the right length. I have a piece of 3/16" steel flat with a 10-32 hole in it. If you grind the screws down until they're just proud of the opposite side, they're correct for the front trunnion. This flat is sacrificial, since I wanted to figure out the magwell mods on a $15 Tapco flat instead of my expensive AK-Builder underfolder flat.
 

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