The 100 ATR comes in several configurations, including an iron sighted version and one with a choice of recoil pads that adjust the length of pull. This offers end users many options. The 100 ATR Night Train I tested has a one piece moulded stock and a bipod.
The 100 ATR has a button rifled fluted barrel with a recessed crown. The thin taper made it lightweight and handy.
At the heart of the Mossberg 100 ATR system is the Lightening Bolt Action trigger sytem, a very responsive product. The adjustment for this system is shown here.
Mossberg uses a Lightening Bolt Action trigger system, which has a distinctive crescent shaped protrusion from the trigger. It was crisp and consistent, on par with many more expensive rifles.
I recently tested the Mossberg 100 ATR Night Train Bolt-Action Rifle in .308 (hereafter called the 100 ATR), a bolt-action centerfire rifle with a 4+1 magazine and a lightweight fluted barrel. It turned out to be a light package for flinging .308 rounds; but it is an amazing value, considering the price. To put this in perspective, it is roughly half the price of similar types of rifles designed to do the same job.
O.F. Mossberg and Sons Inc. is primarily known for its shotguns. Actually, Mossberg is the largest pump gun manufacturer in the world, and the “Made in the USA” stamp on the 100 ATR makes me like it more. This is a company with a stellar reputation for reliable and rugged law enforcement products.
The 100 ATR weighs 8.5 pounds with the included bipod. It handles like a scout rifle, a concept originally refined by Jeff Cooper, which defines a lightweight, handy, accurate rifle designed for general field use. A scout rifle generally weighs about 6 to 6.5 pounds. With the bipod and scope removed from the 100 ATR, (I shot it from Caldwell rifle rests) it weighed about 7 pounds. This is lighter than most rifles specific for police tactical intervention. It is appropriately a matte-finish product, with an even coating on all metal parts.
The 100 ATR has a semi fluted, button rifled barrel with a recessed crown. The barrel is tapered and profiled with a relatively thin contour for this application. Usually, this is beefy barrel territory. I am partial to a barrel contoured like a target rifle.
I usually shoot in some pretty warm climates. This time, my range sessions were in moderate weather, but I had enough rounds to see how well the barrel dissipates heat. It did well enough on the range to make me think, “I could get used to this.”
Lighter rifles are easier to tote around. I’m guessing that is the purpose with the 100 ATR. It was much handier than its contemporaries. Mossberg included a sling (which is usually a sporting rifle accessory). I wouldn’t think twice about lashing this to a pack, considering I have winter boots heavier than the stripped down version of this rifle. It also seemed rugged enough to take a few knocks and still deliver consistent groups. Where would I use this rifle? I have some LE friends who drop in via chopper and ride in via 4x4 to clandestine labs and growing sites. The 100 ATR is a natural fit here.
The bolt and receiver design looks a lot like a Howa, a product I have only had the pleasure to shoot once. It is a two-lug bolt with about 60 degrees of throw. The surfaces mated fairly well and the bolt moved smoothly in the boltway. It has a squared off claw extractor and plunger ejector. The recoil surface (where the bolt cradles the cartridge head) has plenty of steel for high pressures and long service. For a tactical field environment, it should be noted that the bolt travels through two stages after disengaging. Again, it has a great tactile feel, but it can be noisy.
On a tactical gun, the officer should be able to operate everything (except steering the projectile) blindfolded. The 100 ATR has these features, including the fact that one can touch the rear of the bolt and determine the firing pin is cocked and the operation of the safety. Mossberg should be commended for the fact that the “feel” of this rifle is consistent and solid.
Mossberg was kind enough to include a spongy recoil pad on this model. I said it was lightweight. Light rifles firing effective cartridges have a tendency to beat on the shoulder. I’m pretty used to this, but the pad helped. However, since the included scope had a moderate eye relief, one should be conscious of scope bite on this package.
This rifle came with a Barska 4x16 x 60mm variable scope mounted on its Picatinny rail. I spend a lot of time looking through optics and I would have picked a different optic for this package. Even an untrained eye can detect the aberrations I found at 200 yards, which prevented users from turning it up to full power without distortion. I could go on, but one gets the picture. It is a cost effective scope in a high stakes business. My pick for this one is a Millet 4x15x60 Tactical Riflescope, a moderately priced scope for moderate engagements. Yeah, I know it costs the same as the rifle. It’s a better fit for the job.
The 100 ATR receiver is bedded into a synthetic, one-piece stock. Usually, one piece means that the stock is molded and fixtures are attached later. On the 100 ATR, the sling swivel inserts and the trigger guard are molded into the “one piece” package. This makes the stock lighter and keeps costs down. At first I didn’t care for the design but it is snag free and ideal in a drag bag, especially the integrated trigger guard. The 100 ATR has a safety that sits at the right rear of the bolt. Between the taper of the grip and placement of this safety, most users will enjoy instinctive operation. I found I could switch the safety on or off without looking at it or surrendering my sight picture. I also like it when the manufacturer makes a bolt gun that can be placed in battery with the safety on or off, which is an important quality in a tactical rifle. In fact, one can touch the center of the bolt and know the firing pin is cocked. This is truly an “eyes on target” rifle.
I like a little less taper in the forend and a higher, wider (or adjustable) comb, but this rifle was a natural fit for most shooters who tried it. The barrel is free floated over the stock and the free floating remained consistent, regardless of how much I heated the barrel. The stock did have a distinctive “ring” to it when firing, which reminded me of those one piece molded PR 24 batons on a practice dummy. I can’t stand molded batons, but the ring of the 100 ATR felt perfect.
The Picatinny rail comes standard on this model, and it is just long enough for appropriate scope mounts. It has a generous milled opening for loading, which is important because the 100 ATR uses a non-floorplate magazine.
On a bolt rifle, having a magazine without a floorplate requires that the shooter know how to unload unfired rounds without chambering them completely. If it had a floorplate, one releases the latch and the rounds, spring and follower pop out of the bottom. On the 100 ATR, it is tricky to scoop unexpended rounds out of the magazine. The most likely scenario is to let the bolt strip the rounds from magazine without chambering them entirely, kicking them out one at a time, while the rifle is pointed in a safe direction.
The magazine and follower did work as advertised, though. Shooters who practice cycling the bolt quickly for a follow up shot will find that the 100 ATR is not finicky.
The 100 ATR came bore sighted. I fired the first group at 100 yards, gambling on the rough zero. The group was on the 2 o’clock about 4 inches high, but it was on the paper. I adjusted the scope only once and shot several sub 2-inch groups with several brands of ammo. It seemed to like the Federal 165 Grain TRU. This is one of my favorite cartridges also. This rifle only occasionally produced sub MOA groups, but it could pound out 2 inches at 100 yards all day long.
For a mid range rifle, a 2-inch group at 100 yards is about right. There were several instances where the groups were sub MOA. This is what the end-user will discover on his own.
Mossberg uses a LBA (Lightning Bolt Action) Trigger System, which is has a crescent shaped protrusion from the finger pad area of the trigger. I liked the feel of this trigger. It had almost nonexistent creep, and fairly quick lock time. The instructions that came with the rifle say the trigger was adjusted at the factory. The setting was light enough for field work and the trigger was crisp enough for mid range shooting. Really, if this is a cost-effective package, I would like to try the custom models. Mossberg did its best work here.
The Mossberg 100 ATR Night Train is a moderately priced rifle with the right features for a service gun. It is simple to operate, easy to tote around and accurate enough for the job.
Lindsey Bertomen is a retired police officer who teaches at Hartnell College in Salinas, Calif. Reach him at firstname.lastname@example.org.