A shooting instructor once told me that shotguns are made to fit a person who is around 6 feet tall and 180 pounds, give or take. If you fall much outside those parameters, and maybe even if you don’t, an off-the-rack gun is not going to fit you properly — and a shotgun that doesn’t fit will lead to all sorts of problems with your mount and form. Most importantly, a shotgun that doesn’t fit isn’t going to shoot where you point, and that leads to misses. I admit I’ve been guilty of shooting an ill-fitting gun for years, and my shooting has suffered for it.

This point was driven home to me last week at a trip to Gunsite Academy in Arizona. Gunsite is a Mecca for shooters and hunters, and I was there with seven other women to take the Ladies Shotgun class. Mossberg provided the shotguns — the venerable 500 I was already familiar with. But this 500 had the FLEX system, which I had seen at SHOT Show but never seriously played around with.

Before we started the course, instructor Il Ling New had me mount a gun so she could evaluate fit. “You’ve been shooting a gun that’s too long for you, haven’t you?” she asked. Guilty.

Then Mossberg’s Linda Powell pulled out a box of goodies — assorted stocks, combs, recoil pads, forends and barrels — and each woman in the class started building her own gun. The FLEX system is completely toolless, which makes swapping out components a piece of cake. We would be wingshooting on the first day, so I ended up choosing an adjustable camo stock and a super-thick recoil pad that together gave me a 13 1/2-inch length of pull. Comb height wasn’t quite right — a common problem for women, because we tend to have proportionately longer necks than men — so I added a medium-height comb. After adding a vent-rib barrel and a matching camo forend, I was ready for the trap range.

Shooting clays with a gun that actually fits was an entirely different experience from the years of sporting clays and duck hunting I’ve done with a too-long gun. I’d been mounting my gun “all wrong” to compensate for its bad fit, so it took me a few shots to accustom myself to what a proper mount actually felt like. Years of bad habits don’t undo themselves quickly! Once I got used to doing things the right way, I was smashing clays like a pro. OK, not quite like a pro.

The second and third day of the Ladies Shotgun course was going to be focused on home defense, and a long wingshooting barrel just doesn’t work in those close-quarters, often indoor scenarios. We swapped out the barrels for something shorter and non-ribbed, added an EOTech sight and put on a higher comb to help elevate our eyes up to the optic. The whole process takes just minutes, and you’ve now got the same gun with a very different configuration.

For two days we shot Federal Premium No. 8s, No. 4s, buckshot and slugs out of our home defense-configured Mossbergs, with the holographic EOTech sight providing a perfect sight picture. Shooting birdshot is one thing, but hard-hitting slugs are another — and an ill-fitting gun will leave you bruised (on both shoulder and cheek) after enough rounds of that kind of recoil. The right length of pull and comb height makes all the difference in hit rate as well as comfort in that kind of scenario.

At the end of the class, the guns had to be reconfigured back to their original wingshooting configurations to be shipped back to the manufacturer, and again the process took just minutes.

The FLEX system is designed to be completely modular — sort of the AR-15 of shotguns, as far as configuration and accessory options are concerned. The beauty of the system is that the same gun can work for multiple uses and multiple users, and the parts (stocks, recoil pads, combs) are even interchangeable with Mossberg’s MVP and .22LR rifles. Get a FLEX 500 in 12- or 20-gauge, pick one of three recoil pads, one of six or seven stocks in black or your choice of camo (including a pistol grip), standard or tactical railed forend in black or camo, one of about half a dozen barrels for assorted uses, and you’ve got a gun that fits you perfectly and can be adapted in minutes to fit anyone else in the family. Changing the comb requires an Allen wrench, but every other swap is completely toolless and can be done in seconds at home or in the field.

Where else are you going to get a single shotgun that perfectly fits Mom, Dad and kids? It’s a great system for a youth’s first gun, as well, because the stock and comb height can be so easily adjusted as the shooter grows.

If you’ve been shooting an off-the-shelf gun and never bothered to have it truly fitted to you, you’ll be amazed at the difference in comfort and success rate you’ll get with a gun that you can mount properly and point effortlessly. The Mossberg FLEX system is an ideal way to get that perfect fit without having pricey gunsmithing or fitting work done.