The Windham Weaponry .450 Thumper conversion for AR-15

Does the AR-15 really need an introduction? Today this emblematic weapon has nearly sixty years of service all around the world. It has evolved, in the military field but certainly has also become a bestseller on the civilian market. Economical, “simple” and above all very modular, this weapon allows both recreational and precision shooting, at short and medium distances. Personally, we find many flaws in it…. but as we own more than a handful of them in our safes, we must be pragmatic!

The major interest of the system is to be composed of a lower receiver and an upper receiver. It is therefore possible to vary different configurations of these parts in order to diversify the practices or pleasures. If we talk about the AR-15 on a French shooting range, the majority of shooters will mention its ammunition, the .223 Remington, maybe even the .222 Remington for those nostalgic for a blessed time in France, where before 1995 the acquisition of weapons of this caliber was very simple. The sharpest minds will mention the .308 Winchester for the AR-10 variants, some others the .300 AAC Black Out. For the record, we will leave aside here the question of the names .223 / 5.56×45 and .308 / 7.62×51, dealing here with equipment resolutely intended for the civilian market … well, it seems so! But it is highly unlikely that exotic ammunitions by their calibers or developments such as the .450 Bushmaster or the .50 Beowulf will come into the discussion.

The Windham Weaponry conversion

The conversion reviewed here is about the powerful .450 Bushmaster caliber in a very short barrel, providing maximum sensations. Windham Weaponry was founded by Richard E. Dyke in 2011 at the former Bushmaster production site. From 1976 to 2006, Richard E. Dyke was the owner of Bushmaster, which he sold to take a well-deserved retirement. But an unforeseen event led him to resume his activity in 2011: the owner – a pension fund – decided to move the Bushmaster production unit to the other side of the country, leaving the majority of employees behind. Resuming his activity, Richard E. Dyke founded the Windham Weaponry company (named after the city in Maine USA where Bushmaster’s premises had been located since 1976) by bringing back together many of Bushmaster’s historical employees. The result is therefore up to the challenge: high-quality weapons benefiting from the know-how acquired over several decades. Let us remember here that the Heckler & Koch company was, in some way, born in similar circumstances almost sixty years earlier: on the remnants of the Mauser factories, largely destroyed by the French authorities in the aftermath of WWII; Edmund Heckler, Theodor Koch and Alex Seidel, former employees, created a company that would leave its mark in the history of armaments.

The interest of this conversion called “.450 Thumper” is to be able to use an ammunition that goes off the beaten track and allows to obtain good results in dynamic and recreational shots with strong sensations. It can be noted that the name given by Windham is quite confusing: one would have the impression that the caliber of the weapon is the “.450 Thumper”, but it is not, it is the .450 Bushmaster. It is a powerful ammunition propelling a 230 grains (14.9 g) bullet to nearly 600 m/s (1968 fps) into the 9-inch (228.6 mm) barrel of the weapon, hot stuff incoming! That is about 2682 joules whereas the .223 offers 1719 joules with a bullet of 55 grains (3.5 g) at 991 m/s (3251 fps) … in a 20-inch (508 mm) barrel! Yes, almost 1000 more joules with a barrel half as long! Finally, it can be noted that the energy potential of this weapon / ammunition couple is slightly higher than… a 12-gauge 32 g slug launched at 400 m/s (1312 fps – 2560 joules). There is still to exploit this ammunition’s energy potential effectively in the target. That’s not the topic here… but we are not worried about this last point! Finally, with a 20-inch barrel, the .450 Bushmaster can reach an energy at the muzzle greater than 3700 joules! Somewhere between the 8×57 IS and the 7.62×51 mm… but with a much lower practical range. Indeed, depending on the length of the barrel and the ammunition loads, the bullet can remain supersonic up to about 350 m. A distance that may seem “important” or “insufficient” depending on the jobs envisaged… something to think about.