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Ammo Sig P320 pellet and BB pistol: Part 1

Sig P320 pellet and BB pistol: Part 1

by Tom Gaylord
Writing as B.B. Pelletier

Sig P320 pistol
Sig P320 pellet and BB pistol.

This report covers:

  • Start with the package
  • The pistol
  • Many P320s — which one is this?
  • Light rail
  • Trigger
  • Magazine
  • CO2 cartridge
  • Blowback
  • Large handgun
  • No disassembly
  • Evaluation so far

Start with the package

When is a clamshell package not a clamshell package? Answer? When a Sig Sauer P320 pellet pistol comes inside! Guys, Sig has done the impossible. They have created a clamshell package that does not have to be cut apart to get the product out! What they give you is a cardboard box with a two-piece plastic case inside. It makes a transparent window that shows off your new Sig P320 pellet pistol, and, like other cardboard boxes, the gun can go back inside and be stored until you want it again. It’s reusable. They ought to get an award for this!

The pistol

The Sig P320 pellet/BB pistol is a 30-round semiautomatic repeater that mimicks the new Sig 320 firearm the U.S. Army recently selected to replace the M9 pistol. In the world of firearms the 320 is making news because it is an inexpensive Sig pistol. Of course that’s relative, since most Sig sidearms are costly, but the 320 is hundreds less than the norm, and it is modular. Parts can be swapped to give a sidearm in different caliber and one with different ergonomics.

The Army will be getting theirs in 9mm, and now you can get yours in .177. Yes, I said .177 and this time I don’t mean just BBs. The Sig P320 is a real pellet pistol! A semiautomatic pellet pistol that has a blowback slide, a RIFLED barrel (yes, I checked), a 30-round belt-fed magazine (you’re going to love that!) and the same size and weight as the firearm. And, yes, it also does shoot BBs.

When was the last time I told you about a true semiautomatic PELLET pistol? Answer? Eleven years ago I reviewed the Desert Eagle pellet pistol. I called it the first pellet pistol with blowback. Is this the second one?

Many P320s — which one is this?

Sig has brought out a plethora of P320 pistols in various configurations for different tasks. I think the pellet pistol I am looking at is styled after the P320 Nitron Full Size, which is chambered in 9mm, .40 S&W and .45 ACP. The pellet pistol is a full-sized handgun.

All the controls are in the correct place, but not everything works. The drop-free magazine works when the release button is pushed, but the disassembly lever doesn’t move. The safety switch is above the left grip and takes a stout push to engage and disengage.

The sights are fixed with two white dots inn the rear and a white dot in front. The rear notch is wide and the front post is wide and square. With strong lighting on the target I think I can do good work with these sights.

Light rail

There is a Picatinny light rail cast into the front of the gun’s frame. That’s for your tactical lights and lasers. I had to pay several hundred dollars to get the same thing on my Wilson Combat CQB.


The trigger pull is strange. It’s a long pull that feels like single action, but it stacks near the end like a double action pull. It’s long and heavy for a single action pull but light for double action. It will be interesting to see how it plays out in the accuracy test.


The 30-shot magazine has 15 linked plastic pieces with two chambers in each piece. The owner’s manual calls them “seats.” To load you raise a cover on the back of the mag and just stuff pellets or BBs into each chamber as the belt is moved clockwise. You can load pellets and BBs in any order, without regard to each other. The BBs seem to be held in by friction and not by a magnet. I will watch how well this magazine works, because I have seen similar belt feeds in other airguns. Some work well while others hang up.

Sig P320 pistol magazine
To load the magazine, flip the back up and start stuffing BBs and pellets as the belt is moved clockwise.

CO2 cartridge

To install the CO2 cartridge you must remove the backstrap. On the P320, that’s an easy task. The backstrap comes off with a tug on the plastic that surrounds what would be the floorplate. The manual shows the magazine installed when this is done, and that does work, but I found that to put it back on, the magazine needed to be removed.

Sig P320 pistol backstrap off

There is a folding screw tab to help you pierce the CO2 cartridge, yet it tucks out of the way when the grip strap is on the gun.


I just had to see how it felt, so I dry-fired it several times with a CO2 cartridge installed. The recoil is both quick and stout. It will be interesting to see what the shot count is, since it’s going up against the Desert Eagle that uses gas like a dragster!

The slide is solid. What would be the ejection port is just a cast window in the solid slide, and since nothing has to come out of the receiver, it works fine. If you jam a pellet or BB in the barrel, just remove the magazine to gain access to the breech. Then the jammed projectiles can be pushed back with a rod through the muzzle and dumped out the magazine well.

Large handgun

This is a large handgun — fully 1911-size, and the grip is even wider to hold the 17-shot double-stack magazine (in the 9mm firearm). I bet the firearm recoil in 9mm is almost nothing. I mention the size because some shooters have small hands and this would seem large.

No disassembly

You can forget disassembling the P320. It isn’t designed for that. And, at the retail price, you wouldn’t expect it to be.

Evaluation so far

The Sig P320 will be an exciting air pistol to test. It’s a semiautomatic pellet pistol that also fires steel BBs.There aren’t too many like it.

I remember touting the accuracy of the Desert Eagle for many years. Is thisa challenger? Perhaps. We shall all see.

author avatar
Tom Gaylord (B.B. Pelletier)
Tom Gaylord, also known as B.B. Pelletier, provides expert insights to airgunners all over the world on behalf of Pyramyd AIR. He has earned the title The Godfather of Airguns™ for his contributions to the industry, spending many years with AirForce Airguns and starting magazines dedicated to the sport such as Airgun Illustrated.

52 thoughts on “Sig P320 pellet and BB pistol: Part 1”

  1. B.B., I picked up a Desert Eagle at a pawn shop and the seal has gone bad (taken a set, I think) and I have been putting Pelgun oil on it periodically for a week or so and it has gotten better but it still leaks a bit. Is there anything else I can do, apart from replacing the seal, which doesn’t look easy on this gun?

    • Rambler,

      You might keep at it, but use more than just a dab of the oil. I had a vintage CO2 pistol that was an instant leaker, but I put a couple drops of Pellgunoil right on the valve (holding it upside down) and installed the CO2 cartridge from above, and after four or five CO2 carts it became an extremely slow (2 or three days) leaker, something I could live with.


        • Rambler,

          You mentioned above that you don’t plan to leave full CO2 carts in the guns anyhow.

          The official lawyerly take of the industry is not to store them with CO2, but B.B. and others have air guns that hold very well that have had CO2 in them for many years with no issues. Opinions vary on this, but B.B.’s opinion on leaving guns full of CO2 indefinitely is the correct opinion. :^)


          • Michael,

            BB has revised what he says about leaving CO2 in guns. Some of them are designed in such a way that leaving CO2 in them is not good. Those are the ones with small pipes inside to channel the gas.

            The vintage ones that have just a reservoir are fine to leave filled.


            • B.B.,

              Hmmm. Well, the ones in my collection that hold the best/longest tend to be the vintage ones anyway! Still, I might go through a bunch and check ’em out.

              Thanks very much for the update.


              • But what I have seen when a cartridge is left in the gun is not the problem of it leaking then.

                What does happen though is it will compress and form the seal to the shape of the Co2 cartridge head.

                So when the next cartridge is loaded it might have a little different head size and shape. So then it might not conform to the cartridge right. Plus the seal gets smashed thinner. Which takes out the flexibility of the seal.

                All I know is I want the seal in my Co2 guns to not be compressed so they will have there full original shape and flexibility.

  2. It appears it may be a winner. If the fixed sights are pretty much on, the idea of a repeating blowback pellet pistol for half the price of the Desert Eagle. Looking forward to further tests of this pistol.
    Best wishes

  3. B.B.,

    The stacking trigger has me suspecting this pistol is a faux semiautomatic that has the trigger doing something more than just releasing the sear. Are you sure of the ad copy’s accuracy?


  4. I like to see innovation. The belt fed magazine is a nice idea. bb’s and pellets,.. nice too. ( I wonder what mechanism drives the magazine? ) In a way, it is a bit like a revolver mechanism in which a “wheel” holds and advances the pellets. The 92FS I have has a small wheel/clip. The little flip up/down Co2 handle is a nice idea too.

    Good Day all,.. Chris

  5. BB,

    As Michael has pointed out, I am suspecting that this is really a revolver. How does the belt advance, by the trigger mechanism or the slide mechanism? A way you can test this is to remove the CO2 cylinder and place one pellet in the belt near the bottom, insert the magazine and pull the trigger a couple of times. Then remove the magazine and see if the belt advanced.

    You can also work the slide without pulling the trigger and see if it advances the magazine. You could perform that test without removing the CO2.

    Another question I have is whether the belt is the “chamber” or does a probe push the pellet into the barrel prior to firing? If this is indeed a revolver, that would be pretty much out of the question as the advancement would come just prior to firing.

    I guess what I am looking for is what would be a very sophisticated CO2 action pistol. I strongly suspect that Sig’s carbines are also “revolvers”. The Air Ordinance SMG22 uses blowback to advance the belt, but also uses the belt as the “chamber”.

    FX, Hatsan and Evanix have the semi mechanism worked out, but still rely on a rotary magazine. If their actions could be mated to Sig’s or Air Ordinance’s belt magazines, you would really have something there. Imagine a powerful, semi air rifle with a thirty round magazine. There is a company that is making a rotary magazine for the FX Impact that holds 28 .177 pellets.

    • The belt advances via the trigger. If you look at the muzzle side of the magazine there are two open areas. One side is the trigger advancing part and the other side is the “stop”. The trigger mechanism advances the belt and as it’s advancing, the other piece comes out and provides a “stop” for the advancement. This is all prior to the actual hammer fall which is the last thing that happens. The magazine advancing part pushes down on the plastic piece the pellet sits in and then the magazine “stop” is against the same plastic “tube” the pellet rides in but on the other side of the magazine. The timing seems to be pretty precise.

      I should have taken pictures because the operation doesn’t lend itself to the written word very well. 🙂

  6. BB,

    It just came to mind that unless this had an open bolt mechanism such as the Thompson or Sten, you could not remove the magazine with the slide forward if a probe was stripping the pellet from the belt and chambering it. It would have to be very sophisticated indeed.

    • Coduece
      That’s a very good thought. If the Co2 container was big enough to supply the action for a longer period of HPA shots taken. You could have a more reliable action. Plus the HPA would be used more efficiently to get usable shot count. No miss fires when the HOA started going low.

      That is what hinders the FX Monsoons. I know. I had a couple. Fill pressure is everything on those gun’s to make the gun cycle correctly for a given weight and fitting pellet to the barrel.

  7. I have the black version of this pistol. It would be a reasonable purchase if priced at about $60. To their shame, SIG promotes this pistol as a replica and training aid. However, notice that the “slide lock” is really a safety — there is no slide lock. I don’t think the real P320 even has a safety (but perhaps the military version will?). The slide does not lock open when the magazine is empty. The pistol is ready to fire when a magazine is inserted — there is no need to rack the slide. The slide release lever is just molded plastic and is not function. This is not a replica or training aid – it is just an overpriced toy that depends on the Sig name for sales. I’m keeping mine but hope that someone (especially KWA) will soon make a real replica of the Sig P320.

    • BB and the group. I have been thinking and with out a full cup of coffee in me this morning, granted a very dangerous thing to do.I don’t remember you doing a test of the Sig P226 pellet pistol. Your rest of the P226 X5 open BB pistol was so good I bought one . That would be another blow back pellet pistol with a rifled barrel for 1/2 the price of the Desert Eagle. If you did test it a link to the test would be nice.

    • Gordonsbuck,

      Keep in mind that I know less about powder-burners than anyone else here, but might the firearm P320 have an internal drop safety plus trigger safety a la Glock? Also, might the firearm be fire-able in DA for the first shot? If so, that might eliminate the need to rack the slide.

      Just the 2 cents of a firearm neophyte,


    • Finally someone to call Sig out. They think that their name and a cheap facsimile will make you buy this to train with . No .You use a replica like a 1911 or S&W MP 40 that is a functional replica of the actual firearm . You do that to learn the manual of arms for a real firearm and to develop muscle memory and familiarization . This imposter does not do that. Sig needs to decide if they want to build quality airguns or just play make believe.

  8. It will be interesting to hear about this new gun whose firearm version has replaced the Beretta as the army’s pistol. Surely the appeal for the firearm is more than just being cheap! Since part of the objection to the Beretta was the lack of stopping power with its 9mm round, I wonder how the new pistol is supposed to correct that?


  9. I was just thinking it might be a way to cycle the action on a semi auto air rifle without using the hpa. I doubt it would be worth the extra shots but I wondered whether it had been tried before.

  10. BB
    If the slide doesn’t cock the hammer or insert a pellet into the barrel it’s nothing more than a moving part that uses up CO2 and looks impressive. Means the pistol is really a revolver. The trigger pull is doing everything.

    Perhaps we need a new classification, a semi-auto revolver, revolving semi-auto or just an imitation semi-auto !

    Then there is the new M11 that pulls the inner barrel back into the mag housing to capture a BB, pushes back the hammer till it slides off and strikes the valve in the rear of the mag, all with the trigger pull. At least it has no slide movement to use up CO2 and the trigger is surprisingly smooth with a good oiling.

      • BB
        Did a little searching on this one, Hard Air did an article too. Evidently Sig does not even call it a semi-auto. Seems the term is being applied for the looks alone and not really an accurate description. It’s being used a lot though in the airgun world lately with all the replicas and has led to some confusion. Perhaps a semi-auto lookalike would be a better description ?
        There happens to be a pic of the packaging there too.

        Although it is called a Sig and claims to be supported by them, I noticed a ‘ Made in Japan ‘ on the frame. But if it’s to Sig specs it’s no big thing. I think all these companies renaming the same airgun made by ASG or some one else in Asia is leading to a lot of confusion.

        I often wonder if the Asian companies design the gun first then look for customers to apply their brand name to it.
        As a collector I’m not impressed with the lack of realism but it is a new belt fed pistol that may find a place in my collection as well as the Umarex SA10, another first. Still undecided but an outstanding sales event tends to sway me in that direction. There are just too many replicas out there to get them all but the outstanding ones are really good replicas. Heck, the real steel guns are looking more like toys these days with all the composite receivers and colors.

        • When I got my p320, I also noticed the made in Japan on the side as well. I thought for sure it would have made in USA on it or something of that nature. Everyone is outsourcing these days and complaining about there aren’t any jobs!!!

  11. I guess stuff like this keeps interested and sometimes buying these replica pistols. With a lot of the higher end pistols made out of pot metal rather then plastic, a strong blowback will eventually self destruct the pistol , I should have kept my non blowback P08 and put up with the hard trigger pull, At least I had a working replica that looked like the real thing, I understand the blow back on this pistol does nothing but provide the tactile response of firing the actual weapon. The frugal side of me says “why” , Save the C02 for more shots . Displaying the gun is still fine. You can tell the folks YUP, this is a replica of the new issued US Army hand gun. I still hope it turns out to be relatively accurate, It would be cool to see 2″ groups at ten meters.

  12. Did anyone else notice what appears to be exposed roll pins in the close up photos? I am not sure what to make of that. Since it does not appear to be a split case design,.. I suppose they are there to hold some internal component(s).

  13. With co2 being self regulating the engineers should be able to get very consistent action, and as small as the systems are on the blow back action pistols they should be able to tuck something away on a rifle somewhere unobtrusive. I think a reliable semi auto with the power of a marauder would be awesome.

  14. B.B.

    Hard Air Magazine posted their review of the Sig Sauer P320.


    Regarding the loading of the CO2 cartridge, HAM had this to say in their review:

    “On the plus side, there’s no screw head or other external mechanism that punctures the CO2 cartridge and makes the pistol “live”. This is because the SIG SAUER P320 pellet pistol is fitted with SIG’s patented cam-lever mechanism that positions and pierces the CO2 cartridge using what appears to be the rear strap of the pistol grip frame. It’s just about invisible and works very well.”

    HAM’s claim for a cam-lever mechanism contradicts your picture that clearly shows a folding screw tab.

    Has SIG SAUER modified the P320 already to eliminate the folding screw tab? Or is HAM wrong?

  15. Love the looks and this pistol sounds good, but, Sig needs to get real on their advertised FPS. Sure I know not all guns meet what is published (some exceed it) but Sig is really bad about it. HAM tested it and only got around 350 FPS. I’m not after all out power, but when you are 100 less fps than advertised, it puts false expectations out there. Read all of B.B.’s and others tests, Sig seems to do this a lot. I’m not knocking the guns, I just think they should lower the advertised FPS a little.

  16. B.B., off subject, looking at the QB Chief PCP on PA, it looks impressive. I can’t help but compare it to the Benjamin Maximus. The Chief is $50 less, but claim the same FPS, both claim the same # of shots. The Chief is heavier, but rewards with a wood stock. Maximus has the great shot curve (velocity drop as the pressure drops) for an unregulated gun. I wonder is the Chief with meet that or beat that? Maybe a test to come? (HINT HINT).

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