Maionchi AZ20 review with Richard Atkins

Two budget priced lighter loads for comfort at a modest price reviewed by Richard Atkins

We are hearing much more about lighter loads at the moment. Considering all the hoo-ha that surrounded the original move from 32 gram to 28 gram shot loads, when a lot of shooters thought their scores would go down, the desire to go to 24 gram loads for clays seems to be growing by itself.

Pondering the reasons for increasing interest in 24 gram loads I suspect there are three main aspects: First is the potential cost saving (although some premium 24 gram loads will cost more than some budget priced 28 gram cartridges).

Another obvious one is lower recoil;  providing the 24 gram loads are not ultra high velocity this is easy to detect for yourself and a very desirable feature of lighter loads.

The key factor then becomes effectiveness: just how well can a 24 gram load compare against a 28 gram load?

I’m sure the well established 21 gram 12 gauge loads, used by many instructors and shooting schools etc, helped spread the word and knowledge that lighter loads can break clays well too. Introduced when lead prices rocketed a few years ago, with many of us glad of a cartridge that helped keep costs down, they remain quite popular. 

We were happy to keep shooting albeit (as we often thought) shooting at a disadvantage; but we also found they were amazingly smooth and soft to shoot with and, to our amazement, we were soon breaking more clays than we anticipated.

I have written articles explaining why lighter shot loads can, and often do ‘punch above their weight’ so won’t re-run that here; but there are sound reasons why.

Understanding the test results

  • Velocity is measured at 2.5 metres from the muzzle.
  • Pressure is the mean breech figure in Bar (as per CIP).
  • SD is Standard Deviation (consistency).
  • CD is the Central Density rating. This records the percentage of the total pellets landing in the 30-inch circle that were also within the inner 20-inch circle
  • Shot size is derived from actual pellet count per ounce and is listed to the nearest UK size, with < and > symbols where shot is slightly larger or smaller than the nearest size. UK No.7 = 340 pellets/oz; UK No.7.5 = 400 pellets/oz; UK No.8 = 450/oz; UK No. 9 = 580/oz.
  • Shot weight is the average actual shot load, measured in grains. 1 grain = 0.065 grams = 0.0023 oz. CV is Crush Value. This is the amount by which the shot is reduced in size when subjected to the standard crush test. A smaller value means harder lead, so a CV figure of 20% is harder than 30%, for pellets of similar size. Smaller shot crushes proportionately more than larger size.
  • Choke boring Nominal pattern percentages at 40 yards are: Half Choke 60%; Imp/ Mod (three quarter) choke 65%; Full choke 70%.

We have featured some of the recently reintroduced Maionchi AZ20 range (and have more for future review) but with growing interest in 24 gram loads we look at those this month.

The distinctively printed yellow, blue and white cartons of 25 carry the shot size and load information weight on the front. Note that the 2.4mm printed alongside 7.5 indicates shot size is Italian, so pellets should be closer to UK shot size 7.

These loads closely follow the make-up of the 28 gram loads we reviewed previously; they even use the same 70mm long orange plastic parallel Martignoni cases with 10mm metal heads. It would be easy to load the lighter load into a 67mm case  and save a small amount on cases and wads, but the longer case permits a longer wad column; especially useful with fibre wad loads.

Primers are the highly regarded Martignoni with paper covered flash hole; these worked reliably, even in older guns.

Propellant powder used is Vectan A24 from French maker SNPE. This
is a single based, small square cut flake, single base propellant for lighter shot loads in 12 gauge. This produced some moderately quick velocities with charge weights of 20.3 grains in the plastic wad and 21.1 grains in the fibre wad load.

It always requires more powder (of similar type) with fibre wads cartridges as they are less efficient than plastic wads at sealing the propellant gases.

Pressures are modest in both types.

The wads in both cartridge types follow the aAZ20 28 gram loads. The plastic wad is the same GT, with longer honeycomb central cushioning section and an efficient gas sealing skirt base wad; this was originally designed by SNIA. The shot cup is shorter, to accommodate the 4 grams less shot.

The fibre wad is an 18mm long, single unit, with laminate film sealing both ends, made by Diana: this is used with two, 4mm thick, over powder ‘nitro’ cards.

Maionchi AZ20 Target Load24 gram 7.5 shot fibre wad

Shot load367 grains
Pellet (count per oz)318
UK shot (size / CV)7¼ / 26%
Pellets in 30in dia (Av)108
Pellets in 20-30in [79]
Pattern  70%
Velocity374 m/s (1,227 fps)
Recoil (M) (unit= Ns)9
Pressure (unit = bar)570

Maionchi AZ20 Target Load 24 gram 7.5 shot plastic wad

Shot load375 grains
Pellet (count per oz)337
UK shot (size / CV)7 / 31%
Pellets in 30in dia (Av)93
Pellets in 20-30in 85
Pattern  62%
Velocity384 m/s (1,260 fps)
Recoil (M) (unit= Ns)9.2
Pressure (unit = bar)445

Shot loads

The shot load is always key in cartridge performance; ultimately it is pellets that break clays. Shot loads were very consistent and within a pellet or two of the nominal 24 gram weight.

Shot in both types were round and nicely polished with graphite for a smooth dark surface finish. They were quite well graded for consistency of size although each type was clearly a different batch of shot. This became clear when checking the actual pellet count per ounce to confirm shot size, with the fibre wad shot giving 318 / oz and plastic wad 337.

This produced an average 21 pellets per load more in the fibre wad cartridges. These differences are not unusual and typical of why it is essential to thoroughly evaluate such things when undertaking meaningful pattern testing.

Unfortunately it is rather time consuming to check such details and so few people actually ever do it but, without doing so, actual pattern percentage results can be some way out.

Shot hardness plays an important role too; the harder shot patterns more closely than softer shot when all else is roughly equal.

The shot in the plastic wad loads gave average crush values of 31%; this is on the softer side and indicates somewhere around 2.5% of antimony. The fibre wad load gave 26% CV which indicates around 3 to 3.5% antimony with this shot size. It would therefore be fascinating to see how these differences play out on the pattern plate and, ultimately, the clays! 

The fibre wad is an 18mm Diana type, with two over-powder ‘nitro’ cards
The plastic wad is the same type as in the 28g shell, but with a longer central section

Laboratory tests

Both these 24 gram loads were submitted to the Birmingham CIP Proof Laboratory for pressure, velocity and momentum testing. Pattern tests were conducted at 40 yards from a 30” long, standard bore size barrel with 2¾” (70mm) chamber with standard length (short) forcing cone and bored Imp Mod (UK ¾) choke. 

The laboratory reports make it clear these cartridges are well put together. Shot and powder loads were consistent in weight and, combined with efficient assembly and good quality control, this has produced consistent velocity results comparable with any price band cartridge – impressive!

The actual velocity figures are, as with the 28 gram AZ20 cartridges, comfortably under the 400 mps but are typical of those found with many successful competition brands. There is a point where higher velocities enter a realm of diminishing returns; higher velocities never come alone!

Recoil is, of course, directly affected by velocity and so the moderate velocity does help reduce both actual and perceived recoil. However, we should also realise that shot load weight makes more difference than velocity does in the amount of recoil a cartridge produces.

That shows in the momentum figures when compared.  A 404 mps 24 gram cartridge recently tested gave 9.7 Ns momentum; a 28 gram cartridge with 370mps velocity gave 10.36 Ns momentum.

Slightly harder pellets in the fibre wad produced a dense pattern
The plastic wad still produced half choke results from an Imp Mod barrel

The AZ20 fibre wad at 374 mps velocity produced just 8.97 Ns momentum: and that feels a whole lot smoother than 10.36! You really can shoot a large number of this cartridge in a day without discomfort or loss of concentration.

If a slightly lower velocity can cause concern, think on this too. The
air resistance encountered by shot pellets retards their progress as the square of velocity; that means that the faster pellets encounter considerably more resistance than slower pellets.

This results in the initial difference, which may seem a lot, being lost to air resistance and their terminal velocities get closer as distance increases. And that is why so many successful cartridges are not hyper-velocity.

A rather fascinating aspect of conducting your own meaningful pattern tests is that you can see for yourself just how long established (but not
always well understood) principles of shotgun ballistics and performance work out in practice. 

It also helps keep some properties attributed to certain components in perspective; such as the influence a plastic wad can make over a fibre wad. Many take at face value that they will get a tighter pattern with a plastic than fibre wad. All else being equal that is likely so; but maybe by less than you think. More importantly, all else may not be equal!

Pattern testing revealed the fibre wad cartridge, fired from the same fixed choke, Imp Mod barrel, produced an average of 70% pattern density (= Full choke) to the plastic wad result of 62% (Half choke +2%).

The fibre wad load is faster which should work against it! The answer is in the shot load; the pellets gave a 15% harder CV reading in the fibre wad cartridges and this allowed the fibre load to exceed the pattern density of the plastic wad load.

If one compares the number of pellets in the respective patterns which, incidentally, were also very consistent with less variation pattern to pattern than frequently found, the fairly large pellet sizes with 24 gram shot loads have fewer pellets per load. This resulted in fairly open patterns at 40 yards despite being half choke plus. 

That’s not necessarily an issue, as you wouldn’t expect to get a second barrel Olympic Trap competition cartridge performance from one of the keenest priced cartridges currently available.

I would really like to see the AZ20 24 gram load offered in 8.5 shot size (UK 8) as per the 28 gram. Just look back at the excellent and dense patterns these 28 gram AZ20 loads produced to see why. 

I’m sure this would be appreciated in those seeking a 24 gram load for general club and minor competition use. On the range, sensibly used, these cartridges worked well. My nearest sporting ground is fibre only and I had a great day using a mixture of these and some AZ20 28 gram loads for the longer targets.

The plastic wad has a shorter cup to accommodate the lighter load

I shot first barrel DTL, where I take my first shot before the 35 yard mark, with both fibre and plastic types and did feel I got better kills with the fibre. The pattern tests, done later, showed why. Having Invector choke in my trap gun I upped the bottom barrel to Imp Mod for first barrel for my next outing and that helped; I usually use 3/8 choke.

I like them both; very smooth to shoot which I increasingly appreciate and a very clean burn. For the closer to approaching middle distance clays, as a great many sporting targets are, they will still do the job. Then use the 28 gram for longer targets and, for the extreme stuff then I always have a box of premium cartridges in my bag; hardly a problem.

Cartridges fit well into the ‘horses for courses’ description despite what some will have you believe. The thing to do is try them for yourself. With a bit more choke you will be surprised how far even a modest pattern density cartridge will do what you require. Remember, all pattern tests (except skeet cartridges) in these reviews are fired through the same Imp Mod barrel. 

Then just go out and try some; they are nice to shoot with, and are a very nice price too! 

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