Engineered plastics, synthetic stocks and modern materials in airguns
by B.B. Pelletier
Blog reader Brian Saada has written a guest blog for today. He wrote one the end of May (More on manufacturing tolerances), and it caused a lot of you to comment. I feel certain today’s blog will do the same thing.
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by Brian Saada, aka Brian in Idaho
“The best airguns are made from metals and woods.”
The above statment may well have been true years ago; but, during the past 20 years, we’ve seen increased use of plastics and synthetic materials in the airguns we shoot, and some that we have yet to buy or shoot.
The word plastics is a hugely broad and generic term that is often misused and even more often misunderstood. Even 30 and 40 years ago, plastic was being used in airgun pistol grips, some sights and other non-critical components (non-critical to the bean counters, anyway). Still, we often equate plastic to cheap, but that’s not always a fair equation. Words such as lightweight, durable, impervious to oils and acids are more in line with the use of well-made plastic parts. Many of you may remember the Remington Nylon 6 rifles — a noble but less than satisfying attempt to make a plastic stock on a firearm (Nylon ages and deteriorates in some applications and does not do well in severe cold).
Today, the term synthetic materials is much more appropriate to these so-called plastics, as many of these are highly evolved materials or fairly recent developments. Since the gun makers don’t do a very good job of describing these materials in their advertisements or literature, I thought that I would do my best to describe what some of these materials are and what their purpose is.
As the name implies, thermoplastics = thermo (heat) and plastic (moldable or malleable material condition). The difference between these plastics and the cheaper and more brittle styrene-type plastics that are injection-molded or cast is in the types of resins used and the material properties. Thermoplastics typically have greater surface hardness, greater density and can often be remolded or bent/shaped under heat. These materials also drill and machine reasonably well and are not prone to cracking like their cheaper counterparts. A well-made synthetic pistol grip would be made from thermoplastic or, as seen below, so would a Crosman 1077 rifle stock.
Crosman’s 1077 incorporates modern synthetic materials.
This, too, is a fairly generic label or term that can be applied to a lot of materials however, it implies that the selection of resins and additives were engineered or thought through based on the application of the material to a specific part of the airgun. The breech of a Crosman 2240 pistol is one example.
Breech of the Crosman 2240 isn’t made of metal.
Somewhere back in the day, some engineer needed to reduce costs, simplify manufacturing and also pop out hundreds of these breech parts per day. That engineer also had some level of durability and surface hardness to achieve in this plastic part. Keep in mind, this is a wear area or wear surface part that will see thousands of bolt actuations over the life of the product, so the actual plastic maker had to select a recipe of resins and possibly some filler additives (solids) that would make a reasonably functional part. It’s likely that this resin already existed in a DuPont or an ICI catalog and no R&D or great development was needed. The engineer looked at a table of properties in the catalog and picked the material that met the need for cost and usefulness.
Another group of materials that fit into this category is the reinforced plastics or molding compounds. As the name implies, the plastic is reinforced with a variety of other materials. Chopped or shredded fiberglass is very common, so are carbon fibers and even nano-particles for very small parts that require long life cycle or use. Titanium particles and other metals can also be used as reinforcement or for machinability on a mating surface of a part. The higher-end airguns, such as the FX brand, likely use these types of materials in their gun stocks as they are very, very strong and their density can be “heard” by the solid thud made when tapping on the stock. More frequently, we would see these types of material under the hood of our cars in air cleaner boxes, ductwork and even intake manifolds on fuel-injected engines (my Mitsubishi V-6 has one of these).
If you’re turned off by plastic use in an airgun, think of the level of durability needed to meet low CTE (expansion by heat) and resistance to all the nasty stuff going on under the hood of a car or truck, including oil, gas and road crud. An airgun is a hospital operating room environment by comparison!
I, too, was once of the “give me metal and wood” school of thought on this issue of plastic parts. But, I can shoot my Gamo Whisper .22 with the camo synthetic stock all day long. Not so my HW97K. About 3 hours of lugging around that 9-lb. monster, and I’m done for the day! Hooray for plastics!