I currently use a Benelli M4 with good results. I'd like to have a detachable mag. How reliable is the Saiga 12 vs other similar auto detachable mag shotguns? Do they run like an AK?

I think you would be happier with what you already have. But everyone needs a new project….

The russian ones are reliable from the factory.  Saiga and vepr.  They were very similar.  The big differences were the vepr uses straight insert mags and the saiga used rock-n-lock.  And the saiga had an adjustable gas block.  The vepr was not adjustable, but was "self regulating".  The vepr was also built tougher, had a BHO on the bottom of the receiver, and was available an RPK folding trunnion.  The way they work is very similar to a normal AK, but not exact.  The bolt head is 2 pieces instead of 1.

For the russian ones, some of them ran great right out of the gate.  Some of them required "break in", which basically smoothed the rails where the carrier rode.  My vepr has been 100% since day 1.

There have been clones from KUSA and imported like the JTS.  Those are hit and miss.  The original design was sound.  The execution of the cloning and whatever corners they cut have made some of them unreliable trash.  There are examples of KUSA rear trunnion rivets coming out in the very first mag.  And I was next to a dude at the range who had SBS'd a JTS clone and it wouldn't run more than 2 rounds in a row.

There's a lot of information on the internet.

The biggest issue with Saiga's was that some had improperly drilled gas ports (Friday afternoon or Monday morning guns).  That was easily fixed.

Are these more reliable than the USAS12? Why is the USAS 12 an nfa item? Is there a way to check to see if the gas ports were done correctly?

 Take off the gas tube and stick an endoscope down there?

IDK about the USAS12 reliability, my vepr is 100% reliable so far.  I cant say if its more reliable, but it definitely isn't less.

For why the USAS12 is NFA, I think it just got caught up in some administrative BS by whoever was running the ATF at the time.  That was in March 1994, right around the time they were pushing the federal AWB.  They were on a roll declaring certain shotguns as DDs by name.  They decreed that the USAS was too heavy to be sporting, and made it a DD.  

The russian ones came in a decade later.  By that time, the political climate had changed.  And there were clear(er) rules about what could be imported as sporting.  The AK shotguns came in as sporters and could then be converted after they were in the country.

That is an issue which also affected some of VEPR-12 production.

Between the 2 (and based solely on internet reading lol) I think it’s less common of a problem in VEPRs.

I’ve only had 1 example of each, but I upgraded to the VEPR-12 and it was quite the upgrade indeed. I never had any reliability issues with my Saiga however.

The Picatinny rail, straight-insert mags, and automatic bolt hold-open on the VEPR-12 are all significant upgrades. I also got one of the early ones with “folding” stock that was spot-welded. (That weld is removable.)

Yeah that’d be the only way to really check that during an inspection.

Owning both, I’ll definitely say the VEPR-12 is more reliable.

Everything about it is better.
Only exception would be the 20rd drum of the USAS-12 is a better drum than the aftermarket 25rd VEPR drums, but the clear polymer rear plate of the USAS drum is prone to aging and cracking around the assembly screws.

Mine is cracked there, but still holding up. The USAS drum cannot accept S&B buckshot because the OAL is too long, but its 10rd stick mags work just fine with them.

Either type of mag is slower to reload into the USAS-12 and it only has a manual bolt hold-open (via the charging handle).

The 8rd Russian stick mags in the VEPR are my preferred option (for if I was employing it as a weapon, anyway). You can still kneel and get into various firing positions with those.

USAS-12 needs 100% hot shells to function reliably, but can still be finicky even with those.

Yep that’s basically it. ATF declared the USAS-12, Street Sweeper, and Striker 12 to be DDs all at the same time (and let people register them tax-exempt for about 10 years after that.) I got my USAS-12 very inexpensively because the original owner had never registered it, and was never shooting it because it was hidden.

I’ve got a Street Sweeper too, and they suck as a combat shotgun. Horrible. lol

I’m really not much of a shotgun guy in general, but IMHO the VEPR-12 is the king of high-capacity shotguns.

For LE work I favor something more svelte like my trusty 14” Benelli M1 Entry. (I don’t have an M4 but they’re great. Berettas too.)

I don’t have mag pouches for my VEPR-12 yet.
It would take an extremely specialist kit setup to go “full battle rattle” with one, and honestly I don’t see a good usage case when compared to other, more popular options. (Spetsnaz must’ve had their reasoning though.)

I really wanted to like my Saiga. We polished the internals ,cleaned up the ports and opened them a hair as well. At the end of the day it was funny and not as reliable as my Benelli. Various aftermarket mags had issues as well. I gave up after throwing a lot of work at it and sold it.

Mine has been for the last 20 years.

Had it since 2004.

I don't shoot it a ton but when I do it works.

I have had several Saigas, both 12 & 20 ga.  I also had a .308 one as well.  One of the 12ga. was a Tromix built gun and ran 100% with anything.  I don't know how much work was done to it by Tromix as I bought it used, but it was definitely nicely done.  The other was a stock gun I converted and found some of the 'Friday vodka' issues with it.  The main issue was the dust cover popping off when I would shoot it.  With some minor repairs, I was able to get it running 100%.  But my home build wasn't as nearly as nice as the Tromix gun.  The 20ga needed hotter loads to run, but ran fine with Estate field loads.  I eventually sold them off for something new.

I had a Verp-12 with the side folder factory stock.  That was my favorite as it was a full factory setup.  But I was so shotgun heavy and I ended up trading it for a motorcycle.  I made out in the end, but I still miss it.

I ended up getting a $325 Chinese made Vepr-12 clone from SDS as I had Vepr mags left over.  It is basically a Lynx-12 that takes Vepr mags.  The last shot bolt hold open doesn't work with my CSSpec mags, but I still prefer the straight insert mags.  It was a impulse purchase as I got a bonus at work.  I ended up picking up half a dozen guns at the sametime, so the Vepr clone just sits.  I really, really need to take it out to test fire.

On the same note, I had several Saiga-12 mags left over as well.  So I got a SDS imported Chinese pump shotgun, the Civet-12, that takes Saiga-12 mags.  It was $225 or so.  It's in my pile of guns I haven't gotten to shoot.  So when I do go to the range, I start with my carry guns and work my way down the list.  The Chinese shotguns are unfortunately at the end of the list.

Between work, other hobbies, life, family, etc., getting enough range time is tough for me.  It's easy to either do a little work or jump in the pool with the grandkids on a Saturday morning.  I work a commission job, so a few hours Saturday morning can make me a chunk of change.