The Windham Weaponry .450 Thumper

The Windham Weaponry .450 Thumper
Want an exciting deer hunt in a straight-walled rifle cartridge state? Or, for that matter, any state that allows semi-auto hunting? Check out the Windham Weaponry .450 Thumper rifle! The hunting jacket worn by DeNiro is battery heated and made by My Core (MyCoreControl.com).

Back in the 1970s, when I was very young and growing up in a city, there weren’t many opportunities to hunt, with the exception of shooting birds and squirrels in some woods near my house, on an almost two-acre lot owned by my grandparents, or at a friend’s property, but that hunting was done mostly with pellet guns. Shooting with real guns was done at The American Range in North Jackson, Ohio, and at quarry mines—not much to hunt there, except for paper targets and rocks. I was mostly a shooter and gun collector, but many times the hunting articles in Guns & Ammo magazine would grab my attention away from articles on handguns and military-styled semi-autos (my true love) and divert my interest to hunting.


I liked camping, and the idea of taking a Winchester Model 94 .30-30 into the mountains on horseback for a deer hunt was a fantasy for this city boy. I didn’t know any deer hunters back then, with the exception of an older cousin’s husband, who had promised to take me, but that never worked out. I mostly stuck to small-game hunting, influenced by one of my favorite gun writers of all time, Bob Milek, who was the real pioneer of handgun hunting in the 1970s and ‘80s. His influence led me to countless squirrel hunts with my grandfather’s Hi-Standard model GD .22 LR pistol, shooting pests with CO2 pellet handguns, rabbit hunting with 1911s, and even groundhog hunts with my Colt AR-15 SP1 at a relative’s farm in the early 1980s. (Bob did a lot of groundhog hunting with the Remington XP-100 bolt-action handgun chambered in .221 Fireball and was the greatest promotor of that gun.)

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Outdoor Sportsman Group’s director of social media marketing, Rudy Bachraty, gets some footage of Windham Weaponry’s VP of sales and marketing, MarkEliason, describing the features of the .450 Thumper rifle at the 2018 NRA Show. (Photo by Joe Kriz)

As far as other types of hunting, I even went pheasant hunting (once) in the mid-1980s, with my grandfather’s J.C. Higgins 20-gauge, bolt-action shotgun, but as far as the firearms hobby in general, I was mostly a shooter, collector, and “class 3” kind of guy. I still wanted to go deer hunting, eventually.

When I acquired property out in the country decades later, the opportunity was in my face, as deer seemed to be everywhere, so I didn’t waste any time. The problem was that my property was in Ohio, and that state only allowed shotguns with slugs at the time for modern long arms. (For other details on Ohio deer regs, see the article I wrote on the TNW ASR, as well as Scot Loveland’s article on the ATI Omni in this issue.) No Winchester Model 94 dream deer hunts in Ohio for me! Handguns over .357 with straight-walled cartridges (no shoulder) were/are allowed, so I could summon my inner Bob Milek and have a ball! And I did, but came up empty during a couple of seasons. I then decided to use a shotgun, as I kept hearing stories of big Ohio deer running a mile or two after getting hit with .357 and .44 magnums fired out of handguns. I am in the very hilly and thickly-wooded part of Ohio, so it’s not like I can see for a couple of miles, as if I hunting on farm land. I wanted less hiking and tracking with my hunting.


I first chose a Beretta 3901 semi-auto slug shotgun, since I was running international sales for Beretta USA at the time (the 3901 series was the only made-in-U.S.A. shotgun by Beretta USA at the time, and I sold those shotguns for export). This shotgun was very accurate, but I sometimes had an issue with the cantilever scope mount throwing the accuracy off if it got bumped around (Ted Nugent told me the same thing regarding the one I sent him). Cantilever mounts are like diving boards and, in my opinion, they are the worst concept for a scope mount.

The big problem with using a 12-gauge is the recoil. Sure, a few rounds fired from a pump when you are wearing a thick hunting coat, and you won’t really feel much, but when you have to sight in a scope, or check your scope every season, you may be firing 20 or more slugs in a row, and that just isn’t fun when firing from a bench—not for me anyway. Even semi-autos will beat you up when firing slugs.

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The other problem with a 12-gauge slug is the drop in its trajectory. As I stated, this is the hilly and wooded part of Ohio that is close to the West Virginia border. Although 100-yard shots are possible on my property, most deer are taken at under 50 yards, so if you sight in your slug gun at 50 yards (what I did), your slug will hit five inches low at 100 yards, even though you may be getting a two- or three-inch group. At 125 yards, only 75 feet further that the 100-yard mark, you had better have your thinking cap on when all of the adrenaline is pumping and you spot a buck at that distance, as the slug will be experiencing a 12-inch drop! Sabot rounds have better performance at these distances, but for me, after a couple of years, hunting with a 12-gauge slug for deer got real old, real fast, especially when Ohio changed the law in 2014. We could now use rifle cartridges…some rifle cartridges.


At first, the law stated that all cartridges had to be straight walled. A slight taper was permitted, but no case shoulder—even the “mild” shoulder of a .44-40 would disqualify a cartridge (FYI: more deer had been taken with the .44-40 fired from rifles than any other from the late 1800s, to the early 1900s). The big downside to the law was that it was cartridge-specific for long arms with some “off-the-beaten-path” options like .444 Marlin, .45-90, .45-110, and .50-110. There were more common cartridges like .45-70 and .454 Casull, but not many that would chamber in a semi-auto rifle (with rifle power), with the exception of the .45 Winchester Magnum, which was only found in M-1 Carbine conversions of the 1980s (these suffered from breakage if done on inferior receivers), and in a conversion done by an AR-15 custom shop.

As single-shot .45-70s (as well as some .444 Marlins) began flying off of the racks of guns shops all over Ohio, I considered an AR-15 in .45 Winchester Magnum, but the cost of the conversion, as well as the idea of reloading for it soured the idea a bit. As stated earlier, handgun hunting was/is permitted, to include all straight-walled cartridges from .357 to .50 (not cartridge-specific for handguns), but I wanted a semi-auto rifle, in order to take advantage of its fast follow-up shots, bullet velocity, bullet-energy increase and accuracy from a full-length barrel. Thankfully, the law was changed a couple of years later, to include all straight-walled cartridges from .357 to .50 for long arms. I’ve always been intrigued by old semi-auto rifles, so I considered the .401 WSL (Winchester Self-Loading), as I have wanted a Winchester Model 1910 rifle for some time, and then, just in time, the .450 Bushmaster cartridge arrived!

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The .450 Bushmaster was developed by Mr. Tim LeGendre, who is the owner of LeMag Firearms. LeGendre was intrigued by gun legend Jeff Cooper’s “Thumper” rifle concept of a hard-hitting round (.44 and greater), which could be used to take on very large game at shorter distances. It seems that Cooper must have spent some time studying old Winchester advertisements for its Model 1910 and its powerful .401 WSL cartridge from the early 20th century (I’m sure that Cooper also had some trigger-time with the .401 WSL as well). LeGendre developed the cartridge concept using a .45-caliber bullet and an AR-15 platform and called it the .45 Professional. After Bushmaster Firearms became interested in the cartridge, Bushmaster engineers began working with Hornady Ammunition. During these early days of the .45 Professional, Hornady ballisticians suggested some changes to the dimensions of the cartridge, and it became the .450 Bushmaster.

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The Windham Weaponry .450 Thumper field strips like any AR-15 and will pack nicely for any hunting trip.

The .450 Bushmaster case is basically a .284 Winchester case (without the neck) at 1.7 inches long and is topped with a .45-caliber bullet, most commonly in 250-grain or 300-grain. The maximum pressure for this load is set at 38,000 psi. Not much is available in .450 Bushmaster, but more companies are coming on board—I was able to test two. Hornady Custom 250-grain FTX “Flex-Tip” (which is safe for loading in tubular magazines) was designed for maximum penetration and expansion. It has a muzzle velocity of 2,200 and energy of 2,686 foot-pounds at the muzzle. My other load is Winchester’s Deer Season XP, which is a 250-grain Extreme Point, which features a polymer tip for accelerated expansion and a tapered jacket designed for penetration on deer. It has a muzzle velocity of 2,200 and energy of 2,686 foot-pounds at the muzzle, which is the same as the Hornady round tested. Most hunting loads retail in the $34 to $38 price range for 20 rounds, but I have heard that a major ammo manufacturer will be coming out with “plinker” rounds at half that cost, which is great news, as it is fun to “destroy” stuff with this powerful round, especially since it is getting launched from an AR-15-type platform.

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This is one impressive rifle. If you are worried about a bear coming after you while you are deer hunting from a blind, or while you are gutting a deer, a semi-auto, .450 Bushmaster-chambered rifle like the Thumper will not only put food on the table, it will prevent you from becoming food on the table for something else.

The .450 Bushmaster is a powerful round designed to take large game 250 yards and in. At 200 yards, it produces almost 1,300 foot-pounds of energy with the Hornady FTX or Winchester EP 250-grain bullet. That’s more than enough to take a large deer, elk, or bear. Firearms News writer and Alaska resident Rikk Rambo has informed me that Anchorage Police are using the .450 Bushmaster in AR-15-type platforms as patrol rifles to deal with the huge increase in brown bears being found within city limits. That’s a big round for a patrol rifle!

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Yes, these are large rounds! The Thumper comes with one five-round magazine, which is a converted 20-round GI-type aluminum magazine.

When the Windham .450 Thumper arrived at my local gun shop, I just couldn’t wait to try it out. Taking it out of the box, the Thumper appears as any standard AR-15. Mine was an early model, which came with an A2 stock, 16-inch 4150 chrome moly vanadium steel barrel, standard CAR-15 insulated handguards, and a five-round magazine. I asked Windham Weaponry’s sales and marketing project manager, Matt Hasty, about the buffer weight for this beastly cartridge, and he stated that it is 5.12 oz., which is the same as Windham’s standard full-size AR-15 5.56mm buffer, which is probably a surprise to some reading this. (For reference, Windham’s .308 buffer weighs 5.36 oz. for the rifle-length model and 3.76 oz. for the carbine-length model, while an M4 buffer for 5.56mm is 2.96 oz.)

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The Windham Weaponry .450 Thumper with beautiful wood stock set from Boyds.

The current .450 Thumper SKU (R116SFSL-450) features a Luth AR-15 buttstock, which adjusts for length of pull as well as cheek rest height, Hogue over-molded pistol grip, and 13-inch M-Lok handguard. Windham also offers wooden furniture from Boyds (boydsgunstocks.com) on special AR-15 SKUs, but does not offer the stock sets separately, so you will have to contact Boyds directly if you want a more traditional hunting look. The .450 Thumper field strips like any other AR-15. (By the way, there is now a .450 Thumper available in a pistol version!)

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The only real difference between the .450 Thumper’s bolt and a standard 5.56mm AR-15 bolt is the diameter of the bolt face.

Besides the larger bolt-face diameter and barrel, the only real difference I would like to talk about is the way the Thumper feeds this massive ammunition. What I like about it is that it’s as simple as can be. Standard 5.56mm magazine feed lips hold the .450 Bushmaster cartridge with no issues. It would also appear that there is just another type of follower installed, but that is not the whole story. The folks at Windham Weaponry got together with the folks at Fulton Armory, and Windham just installs the Fulton Armory single-shot magazine follower, which rides on top of your existing 5.56 follower. This adapter works perfectly for the .450 Bushmaster and will also ride smoothly down the magazine body when you load five rounds. I then installed this adapter in an aluminum 30-round GI magazine and after about seven rounds, I experienced some problems, like the follower getting stuck. What I discovered is that this will not work with anti-spring-compression followers, which I had installed in many of my GI magazines many years ago. I then tried the adapter in a standard military, aluminum, 30-round, M-16 magazine with a standard follower, and bingo! Eleven rounds riding up and down the magazine body and no issues with manually loading and unloading—that is maximum capacity when using a 30-round magazine. I didn’t get to try it out with any anti-tilt followers, which leads to the next magazine experiment.

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Fulton Armory’s (Fulton-Armory.com) single-shot magazine adapter rides on top of any existing 5.56 follower and works perfectly for the .450 Bushmaster cartridge in 20-round magazines.

As far as polymer magazines, this adapter does not work in them—I tried Magpul, Troy, Daniel Defense, Orlite, and Thermold. There may be a way to make some adjustments to the adapters to get them to work in polymer magazines, but I did not have the opportunity to try. If you want to shoot .450 Bushmaster in an AR-15 platform, or add extra capacity to your shooting experience, you will have to stick to GI-spec aluminum magazines. The other thing I noticed is that the 20-round size magazine was riveted at 13⁄8" from the back-bottom of the magazine. When the Fulton Armory adapter is removed, the standard 20-round magazine, which was adapted for five .450 Bushmaster rounds, holds 15 rounds of 5.56mm. (This type of magazine riveting for limiting round capacity is commonly done in Canada.) Most states limit capacity to five rounds for deer hunting, but Ohio is limited to three rounds total, including the one in the chamber, so my magazine would have to be modified to hold only two rounds. I did this with a wooden dowel rod cut to the proper length.

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After bore-sighting the scope, I wanted to get a feel for the wood set from Boyds so I installed it—great stuff and looks and feels fantastic. Then, I set up some steel from ShootSteel.com, a 12" x 20" torso-shaped target, at about 45 yards. Offhanded, the big .450 Bushmaster rounds impacted the target and knocked it over. After readjusting the target, I filled up a one-gallon milk jug with water and blasted it at the same distance—what an explosion!

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Now you see it, now you don’t! The .450 Bushmaster round obliterated a one-gallon plastic milk jug filled with water at 45 yards.

Now that I was thoroughly impressed, as well as excited, I decided to do some real blasting, so I took the modified 30-round magazine, loaded it up with 11 rounds of .450 Bushmaster greatness, in the form of Winchester Deer Season XP 250-grain Extreme Point ammunition, and fired away. Cases eject at 2 or 4 o’clock (depending if they hit the brass deflector—I watched on slow motion video) and land about six feet away. No malfunctions with this magazine for nine rounds and less. With 11 rounds, the first two would hang up and not feed properly. This probably has something to do with the large rounds trying to make the curve in the magazine.

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Initial “dress-up” of the Windham .450 Thumper: CAA light mount with green lens-equipped Ledwave Raptor light, Harris bi-pod attached to a CAA P-rail, sling-stud adapter, CAA aluminum four rail handguard, and Butler Creek nylon sling with cartridge holder.

Later, I went ahead and put my own touch on the Thumper—sort of a “tactical hunting” look, so the wood came off and the A2 stock and grip went back on. My customization was what suited me for where and what I was doing initially. Since I would take it into the woods long before deer hunting would start, I added a CAA light mount with green bulb-equipped Ledwave Raptor light, Harris bi-pod attached to a CAA P-rail sling-stud adapter, CAA aluminum four-rail handguard, CAA magazine holder, and Butler Creek nylon sling with cartridge holder (some states do not allow deer hunters to carry extra magazines), and topped it off with a Burris Fullfield 30 4.5x -14x scope. The idea was that I may see a coyote while giving it an “out-in-the-woods” test.

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Also attached: a CAA spare magazine holder, and the rifle is topped off with a Burris Fullfield 30 4.5x -14x scope.

I didn’t see much in the way of varmints, but I did have some fun blasting some stumps and rocks. I was constantly impressed by the power of this cartridge and the reliability of the Windham Thumper to feed and extract this new round. Powerful and fast follow-up shots are a must if you are in bear country. Black bears have started to venture into eastern Ohio at a much higher rate than in years past. Last year, a black bear picked up a 50-pound bag of bird seed from the back porch of a neighbor’s house with its mouth and carried it into the woods. This rifle makes me feel much better when venturing into the woods.

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DeNiro firing the Windham Weaponry .450 Thumper with a converted 30-round magazine which will hold 11 rounds but would only function reliably with nine. The Thumper will wreck most things in its path—biological or mechanical!

After stripping off a few accessories, it was time for the bench. I took the Thumper out on two different occasions to test for accuracy and chose 100 yards for the distance. I began with Hornady Custom .450 Bushmaster 250-grain FTX. With the first couple of five-shot strings, I got 2.9-inch and 3.1-inch groups. My third group was a hair over one inch. Recoil was sharp, hard, and directly straight back, without much muzzle rise from the bench. Since I was shooting from a rest, the butt plate of the A2 stock was kicking against the upper portion of my shoulder, which is an area that wouldn’t get near as much recoil attention as if I were standing. I still took my time, as long as a couple of minutes between shots. This is a good time to mention the trigger. Having owned dozens of AR-15s (and a few M-16s) since 1978, I can say that this is just an average AR-15 trigger. I have spent four decades squeezing them so I don’t feel the need to swap it out for a two-stage trigger with a two-pound break or whatever the “experts” are recommending these days.

The trigger that came with this rifle is just fine for hunting or target shooting with the .450 Bushmaster cartridge, but if you don’t like average AR-15 triggers there are many options out there.

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With most deer taken at 50 yards or less, in the heavily-wooded and hilly part of Ohio, the Windham Weaponry .450 Thumper is a sure bet that you will use up your deer tags. This five-shot group measured .85 of an inch with all Winchester Deer Season, 250-grain Extreme Point, .450 Bushmaster rounds landing almost on top of each other.

Next up was my only other load: Winchester Deer Season Extreme Point 250-grain EP rounds. All five-shot groups were well under two inches with an average of 1.7 inches, so I was very happy with this ammo. Although the Winchester ammo had an impressive best group of 1.4 inches, it did not beat Hornady Custom’s best group of one inch. Since Hornady’s .450 FTX average group was 2.4 inches and behind the Winchester .450 EP average of 1.7 inches, I decided to shoot a few more strings of Hornady Custom FTX to see if it was me that caused the groups to open up a bit. Taking my time again, Hornady Custom again ended up on the larger side, with one group measuring 3.1 inches. It seems that the Winchester load may be a bit more consistent, but you still won’t go wrong with the Hornady load in this caliber.

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DeNiro found the .450 Bushmaster cartridge and the Windham Weaponry Thumper to be one accurate combination.

I then moved on to 200 yards, as I decided to shoot steel plates, which were about 12 inches in diameter. I only had Hornady Custom 250-grain FTX ammo left, so I loaded up the five-round magazine and started shooting. Once I got my hold over figured out, I consistently hit the plates from a braced standing position. After about 20 shots, I went out to 300 yards. This time it was harder, as expected, but I managed to hit that plate two or three times out of five from the same standing braced position. This was of course after figuring out the hold over. At 300 yards, the .450 Bushmaster 250-grain bullet drops about 25 inches, compared to the drop at 200 yards of only three and a half inches. For 200 yards and in, I would be very confident hunting with this round, and possibly out to 250 yards. The Thumper functioned flawlessly with the magazines provided and that says a lot.

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.450 Bushmaster Ammo Showdown: Although Winchester’s Deer Season 250-grain EP rounds’ average of 1.7 inches bested Hornady Custom 250-grain FTX rounds’ average of 2.4 inches, Hornady came out on top with the best overall group of one inch at 100 yards. Without the flyer, the group measured 7/8 of an inch!

As far as the recoil, if you are planning on doing a lot of .450 Bushmaster bench shooting or just a lot of shooting of this caliber wearing lightweight shirts, I would strongly recommend a muzzle brake and/or a recoil pad. In over 40 years of shooting everything from long-range rifles to machine guns to 12-gauge slugs out of pump shotguns, I have never had to hold ice on my shoulder after a day of shooting; I did after about 80 rounds from this rifle with a standard A2 stock. My shoulder wasn’t just the usual red color with broken blood vessels, it was also black and blue. As I stated earlier, if you are wearing a thick hunting coat, you won’t even remember the recoil, and if you are only shooting one box of ammo while wearing a t-shirt while standing, no problem. It’s the bench shooting while wearing a thin shirt with no muzzle brake or recoil pad that is going to make things uncomfortable. However, the rubber pad on the Boyds stock solved much of the issue when I put the wood set back on.

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My deer hunt for 2017 didn’t go as I wished. A deer tick disease in eastern Ohio/western Pennsylvania/northern West Virginia killed off a lot of deer for that season. I knew something was up in October of last year, as I just didn’t see many deer around the property, and the activity at the feeders seemed to be light. My younger son did get one, but he usually does (see the TNW ASR article in this issue). If you were wondering, we eat the deer we shoot and enjoy the meat very much.

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The Windham Weaponry .450 Thumper will have to wait until the 2018 deer season to help fill the DeNiro family freezer, as a deer tick disease killed off thousands of deer in Ohio during the 2017 season.

The Windham Weaponry .450 Thumper combines my love for semi-auto, military-styled firearms with a big game cartridge, and to me, that is far more exciting than deer hunting with the .30-30 lever-action I had dreamed about as a kid. I only seem to get deer during muzzle-loading season. Go figure; the “class 3” guy ends up bagging deer with a single-shot muzzleloader—sometimes God likes to have a laugh. But, I think that will change thanks to the .450 Bushmaster cartridge! 

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DeNiro’s son Matthew bagged this seven-point buck in fall of 2018 with the Windham Thumper in .450 Bushmaster.

WINDHAM WEAPONRY .450 THUMPER
Model: R16SFSL-450
Caliber: .450 Bushmaster
Type: Rifle (AR-15-type)
Action: Semi-automatic, gas impingement system
Capacity: 5 + 1 (ships with one five-round magazine)
Weight: 7.2 lbs.
Overall Length: 35.6"
Safety: Manual lever with indicator markings on both sides of receiver
Receiver: Flat-top type upper receiver with laser-engraved caliber
Receiver Material: Forged 7075 T6 aircraft aluminum with aluminum trigger guard
Barrel: 16" chrome lined with A2 flash suppressor
Bolt Material: Carpenter 158 steel
Barrel Material: 4150 chrome moly vanadium 11595E steel
Rifling: 1 turn in 24" – Right hand twist
Stock: Luth-AR buttstock with adjustable buttplate and cheekrest
Fore-end/Pistol Grip: WW free-float fore-end / Hogue overmolded beavertail grip
Rear Sight: None – Ready for optics or other type accessory sights
Front Sight: None – Ready for accessory sights
Packaging: Hard plastic gun case with black web sling and operators manual
MSRP: $1,413.00
Contact: Windham Weaponry
(207) 893-2223,
WindhamWeaponry.com



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