by Tom Gaylord
Writing as B.B. Pelletier
This report covers:
- The barrel
- AirForce Texan .357
- Is JB Bore Paste safe in a barrel?
- Why haven’t we heard of this before?
- What is the accuracy limit?
- What about brass barrels?
- Leather shoes
- What have we learned?
I have been writing this blog for going on 12 years, and before that I wrote The Airgun Letter newsletter for 9 years. In that time I have talked to thousands of new shooters about the accuracy (or lack of accuracy) of their new airguns. This subject comes up more with rifles than pistols, because when a pistol is inaccurate most people blame themselves. But what I am about to tell you holds true for all guns that have rifled barrels.
Today’s blog was prompted by a new reader who calls himself Geo Johnson. George has an RWS Diana 34 that he is having accuracy problems with. We went through the artillery hold, and since I can’t see him shoot I have to take his word that he is doing it right. It makes all the difference in the world if he is putting any pressure on the stock as the rifle fires, but I will assume he is not. I know that a Diana 34 is a very accurate air rifle, so what else could cause it to not be accurate? Loose screws are a possibility, but they are quickly checked.
How about the barrel? I have written about this many times over the years, but since we have thousands of new readers I thought I would go over it again. New barrels do not usually come ready to shoot. They have to be broken in before you will see the best from them. In the firearms world, .22 rimfire shooters have to shoot several hundred rounds through a new barrel to get it to shoot its best. Centerfire shooters have to go through a very rigid process of shooting and cleaning, shooting and cleaning their barrel for at least a hundred rounds. The only thing that makes this unnecessary is if the barrel has been hand-lapped. Lapping is a polishing process that removes all the rough edges from the rifling after manufacture. But not many shooters are willing to pay several hundred extra dollars for that. Despite what you pay for a new barrel, it always needs to be broken in when you get it, unless it has been lapped.
The reason I don’t stress this as much as I stress using Crosman Pellgunoil on every new CO2 cartridge in a gas gun is because most new air rifles are springers that also have to be broken in from 500 to 1000 shots to smooth out the powerplant. That shooting also took care of the barrel. This used to be a big deal with springers, and since springers constitute 95 percent of all new air rifles, it was pretty much universal. Well, times have changed. Spring guns are now coming from the factory much smoother, and shooters may not appreciate that their barrels still have to be broken in.
AirForce Texan .357
This came to a head last week when Johnny Hill of Weatherford Pawn was talking to me about his new AirForce Texan .357 big bore rifle. Johnny is an experienced shooter who knows about breaking in a barrel. He told me he cleans all his new rifled barrels with 1200-grit valve grinding compound, running a brass brush loaded with it through the bore in one direction (breech to muzzle) about 30 times. He follows that with 20 strokes, one way, of JB Bore Bright, not to be confused with JB Non-Embedding Bore Cleaning Compound (called JB Bore Paste), and then cleans the barrel to remove all compounds. I see no reason why JB Paste cannot also be used, though, because it works on airgun barrels. I plan to use it.
This process either gets rid of the tiny burrs left by tooling that is used to rifle the barrel, or it aligns them with the bore. The same thing happens when a lot of bullets or pellets go down the bore.
Is JB Bore Paste safe in a barrel?
A reader commented that a gunsmith told him that JB Bore Paste wears (he said erodes, but erosion comes from from the heat of powder gasses) the rifling. That is an urban legend that goes around the shooting circles. In fact, all winning benchrest shooters use JB Bore Paste when their bores are new and also periodically to clean the barrels. So do many smallbore target shooters. It is completely safe and only removes the metal that’s deposited from jacketed bullets. If you are skeptical, do some research on benchrest rifles and the need to break them in.
Why haven’t we heard of this before?
A lot of shooters will be hearing about this for the first time. There are many reasons for that. First of all, how many shooters will pay $400 for a premium Shilen or Hart barrel? I didn’t say a Lilja barrel because Lilja barrels are all hand-lapped at the factory — and you pay for it. Some Shilen and Hart barrels are also hand-lapped.
Also. how many shooters ever read their owner’s manuals? Many manuals address the need for a barrel break-in period, but most shooters ignore it and just shoot. You are hearing it now because someone asked why his new gun barrel isn’t accurate. In the case of a Diana barrel my answer is — it will be. Either shoot the rifle a thousand times or clean it as I have described in this report. Shooting gradually either removes those rough surfaces or aligns them with the bore, making the inner barrel surface smoother. Cleaning just removes/aligns the imperfections faster. The point is — don’t walk away from a new airgun because it doesn’t seem to be accurate.
What is the accuracy limit?
Most airguns will benefit from either having their barrels cleaned or going through a break-in period like the one I have described. But there is a limit. Experience tells me that if an air rifle scatters its pellets randomly, it may get a little better, but it may never go beyond a certain mediocre limit. A barrel that puts 8 out of ten pellets through the same hole and throws two of them wide in the beginning will probably improve to the point that all the pellets will go to the same place when it is thoroughly broken in. Even if only 6 of 10 go into the same hole, that barrel will probably get a lot better after it has broken in.
What about brass barrels?
All you Sheridan Blue Streak and Benjamin 392 owners will ask if you should do this to your barrels. The answer is NO! Brass barrels will wear from this cleaning method. Those barrels are only broken in through shooting. However, there might be an accuracy flaw in some of them.
Many years ago I bought a new Sheridan Silver Streak and had Tim McMurray at Mac-1 Airguns give it a Steroid tune so I could test it. As I recall I didn’t test it for accuracy first — I just sent it to Tim. So I had no idea how accurate it might have been from the factory. When it was returned, the accuracy was horrible! It couldn’t keep 5 pellets inside two inches at 20 yards.
I pushed a pellet through the barrel from the muzzle to the breech and discovered there was a huge burr at the air transfer port near the breech. Tim had opened that port for his Steroid tune and apparently a burr was left. I returned the rifle to him and he fixed it for free. After that the rifle could keep 5 Sheridan cylindrical pellets around an inch at 20 yards, which is about as good as Silver Streaks get. Brass barrels don’t usually have problems, but if they do it’s almost always a burr at the transfer port or at the muzzle.
Older readers will remember that leather shoes always had to be broken in. A pair of expensive leather shoes might cost five times what normal shoes cost, but they would still blister your feet until they were broken in. After that, though, they were extremely comfortable. Even the very best had to be broken in.
What have we learned?
I hope you have learned that a new rifled barrel needs to be broken in to remove the tiny burrs and imperfections left by the rifling process. Certain barrel makers will correct this problem as part of their manufacturing process. Harry Pope did it and so does Lilja. Some companies offer hand-lapping as an option. But a rack-grade rifle, be it an airgun or a firearm, will need to either be shot-in or cleaned the way I describe above before the accuracy will be at its peak.
I will tell you more about this process when I start testing the AirForce Texan .357 rifle, which is coming soon. I plan to do a before (cleaning) and an after test with the same bullets, to show the benefits of a proper cleaning.