ATI Milsport SGA 410 — All the Advantages of an AR in .410

David Freeman shooting the ATI Milsport AR 410

As a guy who grew up hunting with walnut and steel shotguns, the idea of a Modern Sporting Shotgun — in more familiar language, an AR shotgun — simply would not have occurred to me. However, I was in a position to attend product announcement and product release events where I was presented with the opportunity to shoot some ARs that were shotguns.

The first was an interesting setup where the same AR lower could be mated with either a 12-gauge shotgun or a .308 rifle upper. Pretty interesting and expensive. Then, I had the opportunity to shoot one of ATI’s ARs that was a 410 shotgun. This one was loaded with .00 Buckshot. Can you imagine putting nine 9mm holes in a target 10 yards away with one trigger pull and almost no recoil? That’s what my first introduction to the ATI 410 Milsport shotgun was like. I shot it a few times, then I reluctantly gave up my position in line.

ATI Milsport AR 410, right profile
American Tactical patented its .410 gauge modular upper receiver. When adding the upper to ATI’s lower, you have a shotgun chambered for 2 ½-inch .410 gauge shells and suited for small game, large game, home protection, target and skeet shooting.

.410 Bore

Shotguns were a very big part of my younger life. However, as I grew older and encountered some of life’s aging issues that put me in a wheelchair and blessed me with a considerable amount of shoulder pain, most of my shooting has involved handguns and .22 rifles. The AR 410 motivated me to start thinking of ways to integrate shotguns into my shooting activities.

Then, I came up with an idea. I challenged my sons and grandsons to learn to shoot skeet better by practicing with 410s. The idea behind it is that 410 patterns are considerably smaller than those of 12 or 20-gauge shotguns, so getting that pattern to intersect a flying clay pigeon would be more challenging.

I have several 410s, including a lever-action, over/under, and a couple of break-action single-shots. I purchased the ATI Milsport 410 for more than busting clays. However, it seemed like adding it to the skeet roster would be fun. My family members all agreed after having the opportunity to shoot it.

For me, shouldering the SGA 410 is fun. It shoots like an AR-15, but you can shoot birdshot, buckshot, or any of several special defense rounds that have been developed for the 410. So, what is this AR 410 that American Tactical has developed? It uses the same Milsport lower that American Tactical uses for its AR rifle. As far as I can tell, Milsport is a term developed by American Tactical to identify its brand of Modern Sporting Rifles. When you pair the lower with a shotgun instead of a rifle, it still serves the same purpose which is to provide an action from which to cycle the rounds.

SGA 410

American Tactical patented its .410 gauge modular upper receiver. When adding it to its lower, you have a shotgun chambered for 2 ½-inch, .410 gauge shells that are suited for small game, large game, home protection, target and skeet shooting. Featuring an 18.5-inch barrel with a custom 13-inch KeyMod rail, the Milsport .410 runs on a gas operated, short stroke, balanced piston system.

ATI Milsport AR 410 with Rogers Super Stoc system
ATI installs a 6-position Rogers Super Stoc stock system. The cam-lock system completely removes any slop or play inherent with collapsible stocks.

The Milsport SGA 410 comes with one 5-round American Tactical polymer magazine. Additional 5-round magazines are available for separate purchase. The Milsport 410 will only operate with the patent pending American Tactical polymer 410 magazine. There is also a 15-round magazine available separately.

Since the Milsport SGA 410 is built on American Tactical’s Milsport lower receiver, it can be converted to 5.56 or .300 BLK just by changing the upper receiver. Every Milsport 410 upper receiver is built to regular AR specs and can be installed on most MIL-SPEC lower receivers.

As you know, ARs can be configured in so many ways. As it ships, the Milsport SGA 410 comes equipped with a screw-on cylinder bore choke tube. Other choke tubes can be used, but the cylinder bore choke tube is probably the one best suited for home defense and other close-up work.

ATI Milsport AR 410 upper and lower receiver
Since the Milsport SGA 410 is built on American Tactical’s Milsport lower receiver it can be converted to 5.56 or .300 BLK just by changing the upper receiver.

ATI installed a 6-position Rogers Super Stoc stock system. The cam-lock system completely removes any slop or play inherent with many collapsible stocks. Once the desired stock position has been selected, the stock can be locked down, simply by clicking the cam-lock lever upward. Pressing the quick-release lever will disengage both the cam-lock and the detent pin allowing you to quickly readjust the stock position.

Installed on the KeyMod rail are flip-up front and rear sights, with a blade sight in front and peep sight in the rear. Both are wind drift adjustable. For home defense use, I added a CVLIFE Rifle Sling and a Feyachi FL22-MB Tactical Flashlight 1200 Lumen LED Weapon Light.

Accuracy and Handling

Shooting the Milsport 410 is the most fun I think I’ve ever had with a shotgun. There is almost no recoil to speak of and cycling through the rounds in the magazine can be done quickly. I used 7½ pellet birdshot when shooting skeet. The brand of ammo I used the most was Winchester Super X.

Paper target after being shot with a Winchester PDX1 .410 Defender round
This is what a Winchester PDX1 .410 Defender round does from 10 yards away.

To proof the gun for the home defense role, I shot some .00 buckshot plus Winchester PDX1 .410 Defender rounds which are packed with three, plated, defense disc projectiles and 12 plated BBs. That round seems to be a real manstopper. It sure plays havoc with a paper target from ranges up to 10 yards.

ARs are built to be handled easily under pressure. With the pistol grip, forearm, and a sling, the gun can be carried in the ready mode and brought to a firing position quickly. Nearby towns are experiencing increased crime, including break-ins, and even occupied home invasions. While I want to believe my home is secure from these types of crimes, there is no guarantee.


We have a split-level home and because of my mobility issues, I occupy the lower level which means if there is an attempted home invasion here, I’m the first line of defense. I’ve kept a loaded pistol handy for years. However, the more I become familiar with this Milsport shotgun, the more I think about having it handy to use as my primary tool in response to a home invasion. Writing this article pretty much sealed the deal. I now have the ATI Milsport 410 loaded and ready to defend against any attempt to illegally enter my home.

I can see the day when the younger generation thinks of an AR shotgun the way we older folks think of a pump or a double barrel. It would be the only type they would need for all their shotgunning chores.

What do you think? Have you tried an AR shotgun? Did you like it? What do you think about the Milsport SGA 410 as a home defense weapon?

  • Paper target after being shot with a Winchester PDX1 .410 Defender round
  • David Freeman shooting the ATI Milsport AR 410
  • ATI Milsport AR 410 receiver and pistol group
  • ATI Milsport AR 410 with 18.5-inch barrel
  • ATI Milsport AR 410 upper and lower receiver
  • ATI Milsport AR 410 with Rogers Super Stoc system
  • ATI Milsport AR 410, right profile

About the Author:

David Freeman

David is an NRA Instructor in pistol, rifle and shotgun, a Chief Range Safety Officer and is certified by the State of Texas to teach the Texas License to Carry Course and the Hunter Education Course. He has also owned and operated a gun store. David's passion is to pass along knowledge and information to help shooters of all ages and experience levels enjoy shooting sports and have the confidence to protect their homes and persons. He flew medevac helicopters in Vietnam and worked for many years as a corporate pilot before becoming actively involved in the firearm industry.
The Mission of Cheaper Than Dirt!'s blog, The Shooter's Log, is to provide information—not opinions—to our customers and the shooting community. We want you, our readers, to be able to make informed decisions. The information provided here does not represent the views of Cheaper Than Dirt!

Comments (25)

  1. @Anon E Mouse… It mentions it in the article. Comes with one 5 round polymer magazine. Extra 5 round magazines available and I believe 15 round ones are available for it also.

  2. Surprised there was no mention of how many rounds the magazine holds.
    From the picture of the target, I’d guess 4.

  3. Since the ‘60s I’ve been a fan of .410, and have owned several since that time.
    Early on I realized that the slug rounds didn’t always perform as advertised. Because 410 is a caliber and not a gauge i determined that solid round balls not only gave excellent penetration, but at shotgun ranges were surprisingly accurate. However, because most .410s are tightly choked, a full bore ball could ruin the fixed chokes in my older pumps and double guns.
    I found that .375 lead balls not only fit tightly in the shot cups, but passed the chokes without damage. Plus, the shot cups prevented gas leakage past the load.
    For deer and hogs I normally remove the end of a regular 3” round, dump the shot, and stuff 2 .375 lead balls down to the bottom.
    The results out to 30 yards are impressive.

  4. @Mike… you’re correct that the FA was added at the request of the ARMY and was designed and implemented after Stoner had sold the design to Colt’s. Stoner felt it necessary. The pencil pushers/bean counter procurement folks also specced a different powder than Stoner specified so that also contributed to introduction of the FA. It’s certainly not a licensing requirement, only that a lot of uppers are built to mil-spec dimensions the FA is there, regardless of caliber. But there plenty of “sport” AR style firearms that don’t included the FA or dust cover. As far as “built in hammer”… assuming you mean forward assist… The M1 Garand, M1 Carbine, and M14 also had a form of FA, albeit not exactly like the AR.

  5. I wouldn’t recommend shooting 45 Colt in any .410 unless the mfg will warranty it. I currently own three iterations of the Taurus Judge platform and am very familiar with the strengths and limitations of .410 rounds. I plan to one day own an AR in .410. Lower recoil means quicker follow-up shots on target. Four 00 pellets in the chest with a 2.5″ .410 round vs nine 00 pellets with a 12 ga at similar velocities; both are deadly.

  6. ABSOLUTELY love the .410 AR platform. Bear Creek has a great model…. NO ammo – lack of ammo – $$$$ of ammo.

  7. Pretty interesting being .410 bore. Little pricey. Wouldn’t be bad for potential home scenarios though. Too bad around here .410 isn’t nearly as plentiful or inexpesive as 12ga shells around my parts. Main reason my Mossberg 500 hardly ever gets used. Don’t want to burn the ammo I do have for it so it sits locked up. Kid I work with has an ATI Milsport in 12ga., not totally sure on it’s reliablity but his seemed to have pretty decent fit and finish.

  8. I’d love to have one, I’d love to have a 12 gauge AR style shotgun too. Of course there are lots of guns I’d like to have. I wonder if you can shoot 410 slugs through this? That would add to the fun. With a 15 round magazine it would be a great defensive weapon.

  9. This question is slightly off topic, but I’ve been thinking about this for a while. Why do ARs, NOT in a .223 configuration, have the forward bolt assist? The FBA was included shortly after weapon was put into service, to overcome fouling by the use of early powders. Is it a licensing requirement?

    As far as I’ve been able learn, the M-16/AR-15 is the only weapon with a built in hammer.

  10. Chiappa over/under double badger 22 mag/ .410…one of my favorites for the farm…5 1/2 lbs plenty of power for many kinds of varmits😉. I, too have had zero problem finding Ammo.

  11. Where can you purchase them and what is the price? I don’t see them anywhere on the CTD site. Also knowing whether or not they are capable of running .45LC is helpful. I own two .410s and both are capable of both calibers.

  12. This is for Gery’s comment back on February 28th. Mossberg makes a very fine pump .410 shotgun and ii is available through Academy Sporting Goods, at least here in SC. Cost was a little over $200.00 dollars a couple years ago. Fine gun, bought it for home defense after seeing what one will do to a paper plate at a distance of 50′ shooting the pellets and sabot round. Very impressive. As far as getting ammo is concerned, you do have to look for it, especially the home defense rounds, but its worth it.
    Hope this helps.

  13. Your question, “Can you imagine putting nine 9mm holes in a target 10 yards away with one trigger pull and almost no recoil?”
    NO, not with a 410 gauge unless this is an automatic or this gun chambers 6″ shells

  14. 410 shells in 3 inch are nonexistent in our area. I managed to find some at a new shop that purchased inventory from an estate sale. They were pricey at 40 dollars a box for number 6.
    My 410 is my go to for outside defense and for small game so I want ammunition on hand.

  15. The upward spring pressure of a box magazine can deform paper or polymer shotshells over time. If a box mag-fed shotgun is kept for home defense, I’d recommend periodically inspecting loaded magazines and replacing any shells that show signs of dimpling or bending.

  16. .410s are fun. I have a little .410 Pointer single shot secured by the back larder.

    Have a birdshot shell and Hornady defense load handy for moles, whatever pest, or snake.

    I was playing with this shotgun a month or so ago at the range. It has a tight choke and patterns well .

    so- On a larked tried the two buck one slug Hornady load at 50 yards. Did not really expect to even hit the target. Two hits in the chest about 6 inches apart! I was impressed and tried it again with the same results. Far from helpless but of course my house gun is a 12 gauge with double aught. Just the same one of the genuine toughest guys I know a little younger than me has a .410 in the house, only shotgun he owns. Buckshot loads have enough penetration that is certain. A good feature.
    Bob Campbell

  17. Several comments about not being able to find 410 Bore ammo puzzle me. 2.5 inch shells in various pellet sizes are available from Winchester, Fiocchi, Armscor, Federal and others. Winchester rounds average around 68 cents per round. I do notice some of the defensive rounds are running a buck per round, but not bird shot. Winchester Super X Target rounds are the ones I’ve shot the most of. And yes it pays to actually measure the round rather than go by what’s on the box when shooting them in AR style shotguns. No, you cannot shoot .45 Colt rounds in the AR 410.

  18. Good luck finding 2.5 or that matter even 3″ 410 shells.
    I have a Henry H-110 410 lever gun. It is sweet. It was my bump in the night gun for outside the house. (I have my 1911 45acp for inside) But the lever gun went into the safe when I found a 30 carbine. Gee I really like my 30 carbine more than my 10-22. Finding 30 carbine ammo is almost as hard as 410.

  19. There are several sources for these usable 410 rounds. Some vendors actually cite the packaged lengths so you know they fit But I’ll not list them. But yes they have to fit in the magazine, There are sources less than $1 per round

  20. Yes this is the ideal shotgun class for home defense and hunting, especially for those who can’t handle 12ga recoil anymore. Remington Ultimate Defense 4 000 Buck shot rounds work well. The critical element is knowing the actual length of the unfired round so you know that it will fit in your magazines. The length cited by manufactures is the open hull length that happens after discharge that matches the barrel chamber. If you have been using an AR then all that muscle memory directly applies. I just swap my Charles Daly upper on my regular AR lower. Those 10 and 15 round magazines can blast out more pellets faster then an MP5 9mm. There are more benefits but…

  21. A friend showed me one of these, I think. But it used a 410 shell that could only be as long as a 556 and if I heard it right are only sold by this same manufacturer. At over $2 a round. ???

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