Non-Lead Ammo: Good for Rifle Bores?
March 31, 2011
Winchester has a unique solution to the ongoing trend of nonlead ammo. But our gunsmithing editor wanted to know how the new fodder would affect rifle bores, so he fired close to 2,000 rounds to find out.
It's a situation we have to live with at least for the present. No matter what we believe or think about the effects of lead shot and lead bullets on the environment, we're facing more and more restrictions from both state and federal governments. Much of this legislation was first developed in California and may gradually spread into other states. One of the potentially most serious effects of some of these new laws and regulations is the banning of standard lead-bullet .22 rimfire ammunition.
You may not know this, or have even given it any thought, but more .22 ammo is sold and used in the U.S. than any other single caliber. Sure, folks do shoot a lot of rounds of centerfire ammo, but when compared to the number of rounds of .22 rimfire sold and used each year, that number pales in comparison. Consequently, some environmentalists have brought pressure to bear on various state governments, especially in California, to ban or limit the use of traditional .22 rimfire ammunition using lead bullets.
While this is certainly not good news for any gun owner, it could have been absolutely disastrous for shooters in California. Initially, there was no commercially available alternative for .22 rimfire ammo with lead bullets. Now, however, Hornady, Federal/CCI, and Winchester have come up with nonlead rimfire offerings. Winchester's meets the California environmental requirements by using bullets that are composed of a special tin alloy.
This is really quite a breakthrough, because the design of the standard .22 rimfire bullet imposes some unique requirements on ammunition makers. Of great significance is the design of the .22 projectile. The .22 uses a heel-type bullet. This means that the base of the bullet is actually slightly smaller in diameter than the body of the bullet. The reason for this is that the cartridge case has traditionally been produced with an outside diameter at the neck equal to the diameter of the bullet. In order to get the bullet into the cartridge case, the rear end of the bullet had to be made with a slightly smaller diameter. With traditional lead .22 projectiles, this is not a problem, as the soft base of the bullet would obturate, or swage out, under pressure from the expanding gases when the cartridge was fired to fill the barrel bore. Basically, the hollowbased .22 bullets acted like the old hollowbase Minie bullets used during the Civil War. Lead provided a cheap, practical, and effective solution to this design problem.
While the design aspect of the bullet was important, the biggest problem with nonlead bullets has always been finding a material that is economical and meets the performance requirements of the .22 bullet. What's the use of creating a nonlead alternative if no one can afford it or if it just doesn't work? Winchester seems to have resolved this problem with its new Super-X tin roundnose ammo. It has recently come into production and is now available to the consumer.
As a gunsmith, my first concern was with what effect this ammo would have on a .22 rifle bore. After all, tin is definitely harder than lead. I was also interested in the level of accuracy it would provide. I contacted the folks at Winchester and they graciously agreed to supply 2,000 rounds of ammo for a bit of testing.
Please understand from the get-go that I'm not a scientist; I'm just a small-town gunsmith, and my "testing" is definitely not definitive. I can only report the results that I got with this very limited test.
I happened to have a brand-new Ruger 10/22, in the box, which had never been fired. I figured it would be a good "typical" rifle for shooting this ammo. It was not "specially selected" or given to me by Ruger. I bought it on sale at the local Bass Pro shop. Also, the design of the 10/22 makes removal of the barrel for inspection very easy, which is especially helpful in a project like this.
The photograph made inside the barrel shows the leade before the test-firing.
Obviously, there is no wear yet.
When I started setting up the rifle for the test, I discovered a problem I had to address before I could use it. The original factory trigger pull was way too heavy. It was something only a lawyer for a gun company would love. At 7.5 pounds it was far too heavy to get a decent group at 50 yards, the distance I think is appropriate for testing for accuracy. So I ordered a Ron Power hammer and sear kit for the 10/22 from Brownells. Just by installing this kit, the trigger pull was reduced to a nice crisp 3.5 pounds or so. It's still not what many folks would call a target trigger, but it's one heck of a lot better.
I also picked up some extra 10/22 magazines. You sure don't want to do an extensive firing test with just one magazine. If you do, even firing just a few thousand rounds will take forever--or so it'll seem.
I installed a Bushnell 4-12X Trophy scope that I already had on hand. It's not a target scope, but it is more than adequate for any squirrel rifle and gives me a good read on the accuracy potential of this Winchester ammo.
Before starting the shooting, I used a Hawkeye bore scope to inspect the new barrel and take some photographs of the bore and, most importantly, the leade just ahead of the chamber. This is the point where you have a transition from the chamber into the bore. Normally it's a gentle taper, and it's where you'll most often have erosion and fouling buildup, both of which are death on accuracy. If the Winchester ammo is going to cause any problems, that's where it'll probably happen.
This target demonstrates the effects of bore fouling after 500 rounds without cleaning. The 10-shot group was fired at the 1,500-round mark.
The first day I went to the range, I fired just a little over 500 rounds. I initially sighted-in the rifle and then fired one 10-shot group with the new tin ammo. The re
sults were nothing to get excited about. The 10-shot group at 50 yards was about 3.5 inches center to center for the widest shots. I also fired 10-shot groups at the same distance with standard Winchester Super-X and Xpert lead ammo as a comparison. The groups weren't that much different, generally running around 3 inches.
Keep in mind that it was a brand-new gun with a new barrel, and other than the aftermarket trigger, it was "factory" original--no bedding or other accuracy enhancements.
At the 250-round mark, I fired another 10-shot group for record, and it had tightened up a bit to about 2.25 inches. I had expected this because most rifles see an improvement in accuracy as the barrel breaks in. I fired another couple groups at the 500-round mark, but the accuracy had dropped off considerably. The groups were now at about 4.75 inches. I stopped shooting for the day and headed back to the shop. I wanted to check with my bore scope to see if the drop-off in accuracy was due to fouling.
The accuracy improved after running a bronze bore brush through the barrel. This 10-shot group was fired at the 1,000-round mark.
Sure enough, fouling was the problem; however, this particular barrel did not build up fouling in the same way I normally see with lead bullets. The fouling from the tin bullets was concentrated in the rifling grooves next to the lands. There were no long streaks or ribbons of tin fouling in the bore. On occasion, I've seen that sort of fouling with lead bullets. And I noticed what looked like small pin-head-sized or smaller bits of tin at various points in the barrel. All of this was easily removed with nothing more than a few passes with a standard phosphor bronze bore brush. After just a few minutes of work with the brush, the bore was quite clean with no evidence of tin fouling.
When I went back to the range, my initial groups were smaller, but by the time I had fired another 500 rounds, the groups opened up again. As it turned out, this was to be the norm for this barrel throughout my shooting. If you wanted to keep it accurate enough for small-game hunting, you'd have to clean it after a few hundred rounds or so if your rifle is like this Ruger 10/22.
I was concerned that my test would give me a distorted view of the accuracy of the Winchester tin ammo, so I did some shooting with two other rifles that I knew from past performance would deliver superior accuracy. One was an older Remington 513T Matchmaster, and the other was a large-action Martini match rifle. I fired both with the Winchester Xpert, Super-X lead, and Super-X tin ammo. The 513T gave me a 1.25-inch group with the Xpert ammo, a 1-inch group with the Super-X lead, and a 2-inch group with the Super-X tin ammo. The Martini produced a 0.88-inch group with Xpert ammo, a 0.81-inch group with Super-X lead, and a 1.50-inch group with Super-X tin ammo. With all three rifles, the tin ammo did not perform as well as the traditional lead ammo.
Keep in mind that this was not a definitive accuracy test by any means. But it did demonstrate that all three rifles would shoot tighter 10-shot groups with the two types of Winchester lead ammunition than with the new tin ammo. Admittedly, other rifles might not do this. After all, .22 rifles are notoriously sensitive to ammunition. Your rifle might shoot tin ammo much better than anything else. Then again, it might not.
I continued on with the firing of the tin ammo in blocks of 500 rounds. With each firing segment, I again saw a marked deterioration of accuracy as I approached the 500-round mark. This was always due to fouling. As soon as I cleaned the barrel with a bore brush, the groups became noticeably smaller.
Coffield used a milling machine to cut open the Ruger 10/22's barrel.
One other interesting aspect of this experiment was the mechanical performance of the rifle. Other than brushing out the bore, I did not do any cleaning of the rifle during the entire process. On several occasions I placed a drop or two of oil in the action to lubricate the breech bolt, but that was it. Believe me, 2,000 rounds will definitely gum up a rifle, but the Ruger 10/22 performed in a superb manner. It confirmed its reputation as a rugged, reliable rifle.
An Inside Look
At the conclusion of the firing, I disassembled the rifle and removed the barrel from the receiver. I then placed the barrel in my milling machine and cut open the area above the chamber and at the muzzle. This made it possible to closely examine the throat as well as the bore.
After firing almost 2,000 rounds, and he examined the exposed chamber area for possible damage.
I did not know what to expect when I finished cutting open the barrel and examined the chamber area. The throat where the rifling begins ahead of the chamber was in remarkably good shape. There was no noticeable erosion or wear to the rifling. There were some minor and very faint longitudinal scratches in the throat, but that was about it. It did not look significantly different from any chamber I've seen where only lead ammo was used.
I was also interested in the muzzle, as I have often seen gas cutting or erosion of the end of the bore. This is caused by gas and bits of carbon and powder squeezing by the base of the bullet just as it exits the bore. For just an instant you have a jet of compressed material flowing over the sharp edge at the end of the bore, and with enough time and rounds, this sharp edge will be rounded over. That's why you often get improved accuracy when your gunsmith re-crowns or re-cuts the muzzle. In this case, the muzzle looked just fine with no noticeable wear.
The opened chamber shows wear, but there is no indication of damage from the harder bullets used in the tin-alloy ammo.
At the end of the process I had to conclude that with this particular rifle, at the end of 1,970 rounds, there was no perceptible damage to the barrel due to the use of tin ammo. Now, is it as good as traditional lead ammo? I don't think so. But if I lived in California and had to use a nonlead .22 rimfire cartridge for hunting or general recreational shooting, I could--and would--use it. It wil
l provide acceptable short-range accuracy, and it did not appear to damage my rifle.
I think Winchester did a pretty good job of coming up with a reasonable substitute for regular lead ammo, which many folks simply can no longer use. Is it the ultimate solution to this problem? Nope, but I would fully expect Winchester and the other ammunition companies to continue to experiment and work to provide better and more accurate nonlead ammo in the future. The potential market is just too large to ignore.