So I watched this video, and I have some feedback regarding your concerns/questions. I heard several things said by Nick that made my ears perk and caused me to scratch my head and question it's validity, but I want to stay true to your original topic, so I will focus in on the issue of gun/barrel manufacturers.
This was a quote from Nick when asked about the "perfect slug": "Twist rates are all over the map and sizes are all over the map. The manufacturer doesn't let us know what size the barrels are or what size the choke is. It's a free for all."
Well, this is a half truth! First of all, when Nick started giving examples of gun manufacturers and calibers, he ONLY gave big bores. So when he tells you that these manufacturers are closed lip about parameters and twist rates, he is telling the truth. However, you can easily figure out the twist by slugging the barrel and using a piece of tap as a reference on the cleaning rod. Just start it at 12 o'clock, and count the rotations until it exits the muzzle. Then divide that by the length. Then you have the twist. As far as the size of the slug goes, get a slug that is .001 larger than the groove diameter of the barrel, and you're on the right step to finding the perfect slug for that gun. This is because a good concentric seal is essential to accuracy. You will still need to play with shape and weight, but without a good sealing slug, you're wasting your time. You're also wasting your time if your gun can't generate enough power to push the slug to a stable velocity.
But then he made a reference to not knowing what size the choke is. Well, this would exclude big bores as big bore air rifles don't utilize choked barrels. Only small bore air rifles use choked barrels. This is because 99% of them are designed to shoot pellets, not slugs, and pellets love a choke. The choke is typically the last 1 to 1.5 inches of the barrel, and it concentrically reduces the barrel size by .001" to .002". The choke is designed to regulate the shape of a pellet before it exits the muzzle. But if you're talking small bore, and choked barrels, there's a 90% chance the manufacturer is using a Lothar Walther barrel. And those barrel specifications are READILY ACCESSIBLE on Lothar Walthers website. Lothar Walther uses a twist of 1:17.7 on their .22 and .25 barrels. But if you have a custom small bore barrel (like TJ's), his specifications are readily available as well. His 22 caliber is a 1:16. His 25 acp is a 1:14.
But interestingly enough, Nick only makes his 22 caliber ammo in .217" or .218". Well, the groove diameter of the Lothar Walther 22 caliber air rifle barrel is .221". And the groove diameter of the 22 caliber TJ's, CZ, or Russian Federation barrel is .220". So NONE of the slugs Nick makes in 22 caliber properly seal the grooves of any of these barrel manufacturers. Same with the 25 caliber barrels from Lothar Walther (which remember, 90% of air rifle manufacturers use). Nick's 25 caliber slugs are all .249 and .250. But the groove diameter of the Lothar Walther .25 barrel is .254. So again, the slugs don't properly seal inside the barrel. They engage the lands, but not the grooves. And without engaging the grooves, you're wasting air and destabilizing your slug right out of the muzzle. The high pressure air from the tank is moving much faster than the slug itself is moving. It finds it's way around the slug (through the gaps in the grooves) before the slug ever leaves the muzzle. This turbulent air is just waiting there at the end of the muzzle for the slug to exit.
However, these slug diameters fit beautifully in FX air rifles. You want to know how I know this....? Because FX air rifles don't have rifling. The twist of the barrel is present in the barrel itself (through the length of the barrel) as it's pulled through the extrusion machine at the FX factory. The design is brilliant. But every other barrel manufacturer uses a mandrel to cut rifling into the barrel. So when you push the slug into the rifled barrel, it engages the lands of the rifling and stays put. But since FX barrels don't have rifling, the slug MUST be slightly larger than the inner diameter of the barrel. Otherwise (since there are no lands to engage) it would just slide right out after you cock it and started walking around in a hunting scenario. Ever wonder why FX rifles are so accurate? Well, the way the projectile is propelled down range is the same as other air rifle manufacturers. The only thing that's different is the barrel. And with a barrel that forces you to use a slug that properly seals, it equates to accuracy down range. I wonder what small bore air rifles Nick shoots his ammo out of? Because he said (and I quote) "So we try to come up with bullets that work in the widest variety of guns." But this hasn't been my experience. The shape and profiles of his slugs are beautiful. But I think he's off on his diameters. Since 90% of gun manufacturers use LW barrel, I would think that he would look into swagging slugs in .2215 for 22 caliber and .254 for 25 caliber. THEN he would have a bullet that works in the widest variety of guns. Continue to make the .217 and .218 and .249 and .250 for the FX air rifles, but also swage .2215 and .254 for the Lothar Walther rifles. Same shapes, just slightly larger diameters. There's no reason whatsoever that these rifled barrels can't be as accurate as FX rifles if the slugs seal properly in the barrel.
But in a nutshell, the specifications are easily attainable for the barrel of any and every air rifle. All it takes is a little research. Often the manufacturer will tell you if asked.
This post wasn't designed to demonize Nick in any way shape or form. I think he does great work, and I think he's a great guy. I use his slugs. His price points are amazing. I just think he should consider manufacturing some slugs in .2215 and .254, and watch how much more accurate they are in the rifled barrels compared to the slugs he's currently producing in 22 and 25 caliber. It's the shooters responsibility at that point to know the dimensions of their barrel,and but the appropriately sized slugs.
Just my $.02
