Borescoping Air Rifle Barrels

In this post we’ll follow-up on the previous one about borescopes. This time, we’ll look down a variety of air rifle barrels and observe some basic differences. And, there’s a kick at the end…

The guns chosen here for inspection are simply ones that were ready-to-hand in the HAM offices. The selection was no more scientific than that!


BSA R-10 Air Rifle Barrel

To set a benchmark, let’s first go back to the BSA R-10 barrel. As is well-known, this is produced by the company’s cold hammer-forging process.

What's Inside Your Airgun Barrel? First Borescope Results

Looking straight down the bore, it’s clear that there are 12 lands and grooves in this .22 caliber barrel. Again, here’s the side view of the same barrel. The grooves look to be pretty deep.

This post shows the first photographic results of some investigations inside airgun barrels using a borescope. I think they are very interesting and hope that you will agree. There will be more to come, too...


Umarex Notos Barrel

Now, let’s look at the .22 caliber barrel of the Umarex Notos. Again this has 12 lands and grooves. However the lands are less wide and the grooves wider.

Borescoping Air Rifle Barrels

Below we have the side view of the Notos air rifle barrel. The widths of the lands and grooves look to be fairly similar. The rifling looks shallower, however.

Borescoping Air Rifle Barrels


FX Smoothtwist Barrel

Now we’ll take the barrel from an FX Impact. It’s an original “Smoothtwist” barrel.

It’s well-known that these barrels have a different type of rifling. It’s shallower and is pressed-in from OUTSIDE the barrel, not machined from inside as with most barrels.

Huh???

Yes, the barrel is almost devoid of apparent rifling. For confirmation, look at this side view.

The Smoothtwist barrel is ALMOST devoid of visible rifling. If you look carefully, it’s just possible to see some rifling, but it takes “the eye of faith” to be sure that’s what you are seeing.


QB78 Air Rifle Barrel

Next, let’s take a look at a good old QB78 barrel. It’s a .22 caliber tube. Again this has 12 lands and grooves.

I’d say that the rifling looks to be quite shallow in the QB78 barrel. Here’s the side view.

Borescoping Air Rifle Barrels

As with the BSA barrel, the width of the lands and grooves are quite different in this case.


Benjamin Marauder .25 Caliber Airgun Barrel

Now let’s take a peek down a .25 caliber Marauder barrel. This is almost-certainly a Green Mountain-manufactured tube.

Borescoping Air Rifle Barrels

Here, it’s immediately obvious that there are only six lands and grooves. Is it the same in Crosman-manufactured air rifle barrels for the .177 and .22 caliber Marauder? Dunno. I’ve not scoped them yet.

Here’s the side view. Note the big differences between the widths of the lands and grooves.


Now We See Some Leading!

Although I’ve not mentioned it yet, all the barrels shown above were reasonably clean. So what does leading look like?

Well, take a look at this. WOW!!!

Borescoping Air Rifle Barrels

Here we have the side view of the heavily-leaded barrel of another .25 caliber Marauder.

Looks like there’s a lot more to discover with our borescope!

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