Sighting in a big bore airgun — the TexanSS: Part 2
by Tom Gaylord
Writing as B.B. Pelletier
- For Aaron
- First thing
- Size matters
- Look around for bullets
- Why start at the low end?
- What about the power you give up?
- Physician — heal thyself!
I’m getting an increasing number of direct contacts from my web page because people apparently don’t want to ask their questions in front of this crowd. I hope that changes, because with all the readers we have, the answer is almost always here.
Today’s report is for reader Aaron who just got an AirForce TexanSS and isn’t satisfied with his groups. Fortunately for him I used to work at AirForce, so I know what he probably isn’t telling me and that helps me cut to the chase. How should you sight in a big bore air rifle that has adjustable power?
This report applies to smallbore air rifles, too. But they have pellets with established reputations for accuracy, so the problem is much better defined and easier to deal with. With big bores you are usually faced with selecting the right bullet to fit your rifle and then finding the right power adjustment for that bullet. All in all, this can take a long time — especially if you do not have a background with blackpowder weapons. And when I say black powder, I mean the real thing — not a gun you drop pellets of pre-measured powder into!
Before you do anything, first consider the powerplant you are sighting in. The TexanSS has a shorter barrel than the Texan, so the velocity has to be slower. With a slower velocity you want to use a shorter bullet that is easier to stabilize. Shorter bullets are lighter because they have less lead. The TexanSS will handle bullets weighing from 143 grains for a round ball to 350 grains for a long conical. I would start with a semi-wadcutter of around 200 grains.
If we were sighting in a Korean big bore that has about half the power of a TexanSS, try to start with a lighter bullet, if you can. But there is one other thing to consider before you buy any bullets — the size of the bore.
As I have said very recently, size does matter. We saw it in the report on the .22 rimfire cartridge and again a couple days ago when I ranted in the report, Everything old is new again. The TexanSS bore size is not given on the Pyramyd Air website, so I asked AirForce for the number. They told me it is 0.457-inches. That means a .457 or .458 bullet is ideal — with the .458 being slightly better. When I load blackpowder arms I try to use bullets that are a thousandth larger than the bore — unless I’m shooting round balls that are patched. Them I size 0.005-inch under the bore and use a 0.010-inch thick cloth patch that compresses on loading.
Also do not lubricate the bullets. At the low velocity a big bore achieves, the soft lead bullets are self-lubricating. Adding bullet lube just messes up your clean bore and detracts from accuracy.
Forget pellets! When you shoot at this power lever (above 250 foot-pounds) the real diabolo pellets are not right for the gun. They work okay in lower-powered big bores, but suffer when the power goes too high, because they don’t have the bearing surfaces to handle it.
Look around for bullets
There are many sources for lead bullets online. Look at as many of them as you can find, because you never know where the best bullet will come from. You want soft lead bullets — not hard-cast bullets. Soft lead bullets slip through the barrel with no lubrication and will give the best accuracy. Hard cast bullets will leave smears of lead on the inside of the barrel, forcing the need to clean the barrel more often.
Let’s now turn our attention to the rifle. The TexanSS is adjustable — not for power, as much as to tune the gun for each bullet you use. Yes, the tuner does adjust the power of the gun, but that isn’t it’s primary purpose for being there. It’s to tune the gun to a specific bullet.
The rifle comes from the factory with the adjuster set up high, so I dial it back to as low as it will go. I start at the low end of the power band and work up. I do the same with centerfire ammunition when I reload. Often the most accurate load is near the maximum recommended load, but sometimes it isn’t. My advice is to start at the low end and work up.
With lighter bullets, though, the Texan likes to have more tension on the hammer. Since I start with bullets that weigh around 200 grains (which is light for a .45-caliber bullet) I start around the middle of the adjustment range or a little more.
The Texan and TexanSS have a long cocking lever on the right side of the action. This reduces the effort to cock. To access the power adjuster on the left side of the action, the cocking lever must be forward like this.
The power adjustment wheel is turned by pushing the holes (arrow) up for less power and down for more. The lines are for general reference. For 200-grain bullets I usually begin about here, which is over half power.
Why start at the low end?
The low end is where you most often find the best accuracy. When I tested the Texan I got the best accuracy with all but the lightest bullets when the gun was set below the halfway point.
What about the power you give up?
Power without accuracy is meaningless, so if you don’t have accuracy you give up nothing. You may “only” get 275 foot-pounds with the most accurate bullet. That’s 125 foot-pounds less than the 400 promised by AirForce, and it bothers some shooters. They think they are losing something they ought to get. But what if they could put 6 bullets into 1.5-inches at 100 yards like I did with the Texan?
Physician — heal thyself!
I told Aaron that I hadn’t gotten as far as testing the TexanSS for accuracy yet. I have been stymied by unusual winter weather here in Texas. But I am still on the job and we will soon see what I can get from the test rifle.