OPSol® Mini-Clip™ Short Shell Shooting Solution!

Minishells are becoming quite popular for those who like the 12-gauge shotgun, but do not like the recoil of heavy loads nor the muzzle blast and noise that accompanies shooting them. Normally, I use the 20-gauge for home defense simply because of less recoil when firing slug, or #3 Buck. But I do like the power of the 12-gauge when shooting even reduced recoil slug loads and buckshot.

After firing a Mossberg 500 Security shotgun with minishells, I was sold on the concept. Depending on the load fired, the 12-gauge actually had less felt recoil than the 20-gauge in a side by side comparison.

Minishell shotshells are only 1-3/4″ long Aguila), with some being 2-1/4” long (Nobel Sports) and increase the capacity of pump-action shotguns. They work great in Winchester 1300 shotguns, though other pump guns may not cycle reliably without modification. They are also perfect for use as low-recoil ammunition for single-shot or double guns as well.

Minishell shotgun shells will not properly feed in any semi-automatic shotgun, regardless the brand.

They do seem to cycle through the Remington 870 series of “Ratchety Shotguns” with little problems, but feeding issues do come up at times depending on how well the operator can adapt to cycling the shells. We found that it takes a quick, sharp working of the pump handle to extract and eject the minishells, but even that wasn’t guaranteed.

According to Mossberg regarding the 500 Series of pump shotguns; “The elevator that catches the round to be subsequently fed to the ramp and chamber has been lengthened and widened. This modification will not prevent you from firing regular size shot shells.”

Not that I disagree with Mossgerg’s statement regarding minishells, but apparently the Mossberg 500 Tactical shotgun that I recently purchased and fired did not have this modification, as the first attempt to chamber an Aguila minishell without the Mini-Clip™ from OPSol® resulted in the front of the shell taking a nosedive through the elevator. I will say; however, that 2.25-inch Mini Shells from Nobel Sports chambered fine; they do not require the OPSol Mini-Clip™ to be installed.

Enter the Mini-Clip™ from OPSol®.

The OPSol Mini-Clip 2.0 Flex.

From OPSol®…

The OPSol Mini-Clip™ allows use of 12ga 1.75” Birdshot, Buckshot, and Slug shells                

 Fits: 12ga Mossberg 500, 590, 590A1, and Maverick 88 models.

 Below are some points about the OPSol Mini-Clip:

 Use with Aguila Birdshot, Buckshot and Slug offerings in Mossberg 12ga 500, 590 and Maverick 88 models.

  • Easily installs and uninstalls in seconds to allow use of 1.75″, 2.75″ or 3″ shells as desired by user.
  • Practice with less expensive Aguila birdshot as the recoil response vs. Aguila buckshot is slight.
  • Low recoil of buckshot allows for safe, easy and comfortable aiming and shooting with pistol grip configurations (with proper grip/face clearance, of course). Not confined to hip and laser shooting.
  • Mini-Clip stays in well, but may want to tape in with electrical or Gorilla tape for close contact or heavy foliage environment applications.

 Obviously, there is no need to run out and by a new Mossberg 500 series, 12-gauge shotgun to run Mini-Shells with the OPSol® Mini-Clip™. You can just install the OPSol® Mini-Clip™ in any Mossberg 500, 590, 590A1, and Maverick 88 model, if you already have one. The installation is not permanent; you can easily remove the OPSol® Mini-Clip™ to run standard fodder.

Twain, at OPSol, LLC, provided me with three versions of the Mini-Clip; the original, Version 2.0, and the Version 2.0 Flex to use with the Mossberg 500 Tactical (see my review of the Mossberg 500 Tactical at https://guntoters.com/blog/2018/08/26/mossberg-500-tactical-71-12-gauge/).

Three Versions of the OPSol Mini-Clip: Original (left), 2.0 (center), and 2.0 Flex (right).

Installing the new OPSOL Mini-Clip 2.0 Flex Adapter.

The Ledge Mates to the Receiver.

OPSol Mini-Clip Fully Installed.

OPSol Mini-Clip™

The original Mini-Clip has two ‘ears’ that are pressed inward when inserting the Mini-Clip into the loading port.  The ‘ears’ also has small tabs that catch against the side of the loading port that helps it to remain in place under “normal’ conditions’ (more on that later).

There is also a ledge at the rear of the Mini-Clip that mates with the upper, inner extrusion at the rear of the loading gate. The combination of the ledge and ears helps to keep the Mini-Clip in place.

OPSol Mini-Clip™ 2.0

The Mini-Clip 2.0 differs from the original Mini-Clip in that the ears have been removed and the clip is more of a solid block. As before, the sides are squeezed inward for inserting the Min-Clip into the loading port. The ledge, as before, engages the rear of the loading port.  From all indications, the Mini-Clip 2.0 fits more firmly than its predecessor.

OPSol Mini-Clip™ 2.0 Flex

While maintaining the insertion characteristics of the Mini-Clip and Mini-Clip 2.0, the Mini-Clip 2.0 Flex, the sloping end of the clip has been relieved to allow the clip to flex when the base of the shell strikes the forward edge of the clip. This flex, I believe, helps to prevent the shell from bouncing and helps for better chambering.

Of the three Mini-Clips received, the Mini-Clip 2.0 Flex was the tightest fit in the loading port.

And, according to OPSol; “The Mini-Clip 2.0 Flex has the flexibility to accommodate a wider range of short shell lengths, should Aguila ever want to make an even shorter (or longer) Minishell.”

Installation Instructions:


  1. Put gun on SAFETY. Ensure firearm is unloaded with no shells in the magazine cylinder/tube or chamber. Make sure pump slide is in extended position.
  2. Squeeze sides and insert the back flat end into the loading port at an angle.
  3. Push in so that the OPSol® Mini-Clip™ is in flush to the rear and the bottom. Rack the slide a few times to ensure the OPSol® Mini-Clip™ is in position. It should not move. If it does move, remove the OPSol® Mini-Clip™ and repeat steps 1, 2, and 3


  1. Put gun on SAFETY. Ensure firearm is unloaded with no shells in the magazine cylinder/tube or chamber. Make sure pump slide is in extended position.
  2. Rack the slide to the rear.
  3. Place a finger (your choice of fingers) into the ejection port and push the Mini-Clip downward and outward toward the rear of the loading port.
  4. Pull the Mini-Clip free of the receiver. The shotgun is now ready to receive standard-length 12-gauge shells.

At the Range:

I ran all three Mini-Clips with Aguila 1.75-inch Buckshot (seven #4B and one #1B pellets, which are rated at 1200fps.  Note that this is a version of the ‘Buck-n-Ball’ loading.), and Aguila Lead Slugs (7/8-ounce rifled slug rated at 1250fps)


Nobel Sports 2.25-inch MiniBuck (00 Buck rated at 1250fps) cannot be used with the OPSol® Mini-Clip™. There is simply not enough room for the 2.25-inch shell to clear the loading tube and the forearm cannot be pushed forward to chamber the shell.

Prior to running the Minishells, I ran a couple of Federal TRUBALL – LOW RECOIL RIFLED SLUG (1- ounce slug running at 1300fps) to set a baseline for comparison. (As another comparison, the Remington Slugger in 20-gauge is a 5/8-ounce hollow-point rifled slug running out at 1580fps. This and #2B (when available) or #3B is what I normally run in the 20-gauge for defensive purposes.)

The targets were two standard silhouette set at 10-yards distant, one for patterning the Aguila 1.75-inch Buckshot  and then one for patterning the Nobel Sports 2.25-inch MiniBuck (not running the OPSol® Mini-Clip™), but I also set a standard silhouette at 10-yards and 25-yards for testing the Aguila Lead Slugs for any drop at those distances.

I am going to tell you up-front that this was not going to be an extended evaluation, as I had a limited supply of Nobel Sports MiniBuck (10) that I could run without the OPSol® Mini-Clip™ installed. While I had an ample supply of Aguila Lead Slugs with me, the range that I frequent had a good supply of them – at a cost, of course.  I had ten rounds of Aguila 1.75-inch Buckshot and was willing to sacrifice them for the sake of science.

My plan was to initially run one of each shell with each type of the OPSol® Mini-Clip™. That would give me three per Mini-Clip, with two of 1.75-inch and one of 2.25-inch shells.  That would also give me some left over for some “Play time.”

The synopsis of all of this was that I can shoot the minishells all day, if necessary. The bad news is that, for the bad guy, I can shoot the minishells all day, if necessary. That also translates into more practice time with the shotgun without all of the strain and pain that is normally felt (sometimes for days) after shooting 2.75-inch Buck and Slug fodder even for a short time. The old shoulder just does not take the abuse as well as it used to in my younger years.

In regard to the OPSol® Mini-Clip™ (or clips I should say), I can shoot the minishells all day with the OPSol® Mini-Clip™, if necessary. All three versions functioned well with minishells of 1.75-inch. But, there was once more test to run.  The OPSol® Mini-Clip™ was removed and two 2.75-inch Federal TRUBALL – LOW RECOIL RIFLED SLUGs were shot.

You see, running the minishell is like running .38 Special in a .357 magnum revolver, or a .44 Special in a revolver chambered for .44 magnum. The shorter shell leaves debris in the chamber; sometimes to where the longer .357 magnum or .44 magnum shells are hard to (or will not) chamber. It seemed to me that running the minishells may have the same affect in a shotgun. If, for some reason, I needed to switch to a longer shotgun shell, would there be any issues. Thankfully, the answer is no. The chamber of the 12-gauge, even after firing minishells, did not exhibit any kind of issue when loading full-length shells.

Overall, the evaluation of shotgun and OPSol Mini-Clips went well. Patterning and slug hits were noted as well as shotgun operation with and without the OPSol Mini-Clips.

Now, I did have one additional test to perform, but I am saving that for later.

About That ‘Normal’ Operation:

According to OPSOL; “The OPSol® Mini-Clip™ was designed for recreational shooting. Any other use is at the personal discretion of the shooter.”

Also from OPSol; “Mini-Clip stays in well, but may want to tape in with electrical or Gorilla tape for close contact or heavy foliage environment applications.”

Unloading Minishells:

Alright, so loading minishells with the OPSol Mini-Clip installed is not a problem. What about unloading minishells? Obviously, shooting the darn shotgun until it is empty is a fun solution, but you may not be able to do that. For example, you have had the Mossberg 500 that is in the closet stoked with minishells and you want to unload it for PMCS (that’s Preventative Maintenance and Services for you not familiar with that acronym). Will the OPSol Mini-Clip interfere with unloading? The answer is no. Some like “shucking the corn” to unload the shotgun while others, like myself, like the more passive-aggressive approach and unload the shotgun by way of the magazine tube.

You will notice that the front of the OPSol Mini-Clip is slanted. This slant allows you to successfully load the magazine tube. The front slope will also allow you to successfully unload the magazine tube when stoked with minishells. However, you can remove the OPSol Mini-Clip and unload as follows:

Note: The following procedure assumes that a shell is chambered. Regardless, always perform steps 1 through 6 to check yourself by going through the motions anyway. (How long has the shotgun been stored loaded?) Always assume that a shotshell is chambered).

  1. Move the safety button to the rearward “Safe” position (it should have been there in the first place, even with a LNC (Loaded but Not Chambered) shotgun.
  2. Keep the muzzle in a safe direction.
  3. Press the lock lever and pull the forearm rearward, slowly until the live shotshell is completed extracted and visible in the ejection port. If there was no chambered shotshell, skip Step 4 and continue to Step 5. Otherwise, continue to Step 4.
  4. Remove the shotshell by hand.
  5. Pull forearm completely rearward to release the next shotshell onto the Elevator.
  6. Turn the shotgun so that the Ejection Port faces downward to allow the released shotshell to drop out from the Ejection Port.
  7. Push the forearm completely forward, closing the bolt without a shotshell being chambered.
  8. Turn the shotgun over so that the Trigger Guard is upward and the shotgun remains in a safe direction.
  9. Insert the trigger finger into the Loading Port and press the Cartridge Stop (on the right side of of the Receiver) inward to release shotshells one at a time. The shotshell will spring rearward once released by the Cartridge Stop, but the edge of the base may hit against the Bolt Slide. If this happens, simply lift the base of the shell slightly upward until it clears the Bolt Slide or pull the forearm slightly rearward until the Bolt Slide starts to move upward into the Receiver, thus freeing the shotshell from the Bolt Slide.
  10. Manually remove the shotshell from the receiver.
  11. Repeat Step 9 and 10 until all shotshells are removed from the magazine tube.
  12. Press the action lock lever and pull the forearm completely rearward.
  13. Visually inspect the chamber, elevator and magazine tube to ensure the shotgun is completely unloaded.

The Final test:

How about that final test that I had planned?  This is in the form of a “What-If” question. What if I needed to transition to a full-length shell and still had one or more ‘minishells’ loaded?  I could load a full-length shell (or more depending on what remained in the loading tube), pull out the OPSol Mini-Clip, chamber the full-length shell (or shells), but what would happen when the minishell was next in line to chamber?

To test this, I first had to determine if a 2.25-inch and 2.75-inch shell could be loaded in the magazine tube with the OPSol® Mini-Clip™ installed.  The answer was yes to that question. With the pump handle fully forward, a 2.25-inch 2.75-inch shell can be loaded into the magazine tube.

With the OPSol® Mini-Clip™ 2.0 Flex installed, I could not catch the front lip of the clip to try and pull it upward and outward.The clip is against the bolt when the forearm is fully forward. I could; however, pull the forearm slightly rearward enough for the bolt to unlock a bit without totally extracting the chambered shell or tripping the Cartridge Stop where a stored shell would be released. This gave my finger enough room to slide it under the OPSol® Mini-Clip™ and remove it from the receiver. Then, the forearm was moved all the way forward, which re-chambered the ‘minishell.’

In short, the test failed. However, I continued the test anyway.

The shotgun was shouldered, the chambered Aguila “minishell’ was fired, the forearm pulled rearward so that the ‘minishell’ would be extracted and ejected. The 2.75-inch shell was loaded and fired. This process was repeated for the Nobel Sports 2.25-inch MiniBuck , and then was repeated again to chamber a minishell, which again nose-dived through the elevator as it did before.

This is not something that you want to do in a stress situation.

Actually, and with the Mossberg 500 tactical that I have, everything functioned as I expected it should. The OPSol Mini-Clip must be installed when running Aguila minishells and you cannot mix-and-match different lengths of shells and expect positive functioning.

In short, installing the OPSol Mini-Clip turns the shotgun into an Aguila ‘minishell-only’ dedicated shotgun – at least until the OPSol® Mini-Clip™ is removed.

I would not run “Boo-Boo” with Aguila ‘minishells’ without the OPSol Mini-Clip, as “Boo-Boo” is from an earlier generation of Mossberg 500 shotguns. I would also refrain from running 2.25-inch shells through “Boo-Boo” until it is tested with these shells. The 2.25-inch shells; however, ran fine through the new Mossberg 500 Tactical.

To Summarize:

Three Versions of the OPSol Mini-Clip: Original (left), 2.0 (center), and 2.0 Flex (right).

As OPSol has stated; “The OPSol Mini-Clip™ allows use of 12ga 1.75” Birdshot, Buckshot, and Slug shells.”

Because the OPSol Min-Cllip can be quickly installed and removed, the transition from minishells to full-length shells is easily done.

How does the OPSol Mini-Clip fare? Well, let’s just say that I will not be running ‘minishells’ without a OPSol® Mini-Clip™installed in any Mossberg 500 12-gauge shotgun that I own.

So, which is best; the Mini-Clip, the Mini-Clip 2.0, or the Mini-Clip 2.0 Flex?

From my findings, I have to go with the Mini-Clip 2.0 Flex. The 2.0 Flex had the tightest fit in the loading port, but not tight enough to where great effort is needed to remove it.

Ayup! If you intend to run Aguila ‘minishells’ in your 12ga Mossberg 500, 590, 590A1, and Maverick 88 model shotgun, I highly recommend using the OPSol® Mini-Clip™ for reliable and trouble free functioning. Is it a perfect solution? Well, nothing is perfect, but it does allow you to shoot minishells through the Mossberg 12-gauge with some degree of confidence that is greater than not using the product.

The only question that should remain, then, is whether you actually want to run 1.75-inch minishells. I have included a couple of reference videos in the Resources section. I do; however, take exception to a statement the presenter makes in the Home Defense: Aguila 12ga. mini shells video; something to the effect of, “Who needs that many shells in a shotgun?” I’ll just say that the presenter lost some credibility, in my opinion.

For me, running a 7/8-ounce Aguila rifled slug ‘minishell’ through a Mossberg 500 shotgun at roughly 1200fps warms the cockles of my heart and lessens the recoil of doing such, as recoil felt no more than shooting a MSR. And, having ten of these puppies at my disposal doesn’t hurt my feeling at all. And, installing the OPSol® Mini-Clip™ 2.0 Flex makes shooting them happen.





About Taurian

Taurian is a U.S. Army veteran and former LEO and Defensive Tactics Instructor. Taurian also has over fifty years of experience as a Technical Writer and Training Program Developer. After leaving home at the age of ten without any shoes, Taurian continues on with many years devoted to the keeping and bearing of arms.

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