Archive for January 2006
by B.B. Pelletier
We had a comment last week from DB, who says, “I have had some interest in these precharged airguns but the prices for the pumps seem to me to be way out of line, and scuba tanks are even more expensive. You can buy a really nice firearm for less than the cost of this gun [Career 707 Carbine] and pump. Is there any economical option in our future? My wife would kill me if she thought that I would spend $200 on a pump!”
I want to put the prices of precharged guns and gear into perspective for you. Before Daystate began making precharged rifles in 1980, they hadn’t been made since before World War I. New guns were still sold in the early 1920s, but they were assembled from parts made before the War. In today’s money, those smallbore airguns started at a low of about $1,000 and went up rapidly. They developed less than 200 foot-pounds, and their pumps sold for hundreds of dollars (adjusted to today’s prices).
The 19th century was the big-bore heyday
The finest and most powerful big bore guns were made during the 19th century. Power levels got as high as, perhaps, 300 foot-pounds, and guns were sold in kits with all the tools and equipment needed to make them work. A starting price for a complete kit was around $2,000 of today’s money, but the price quickly rose to $10,000 and more on the finer models. These were gorgeous guns, for sure, but they didn’t use scopes and all had to be filled from hand pumps. If one of today’s big bores had been around, it wouldn’t have been inoperative, because no one had the means to charge a gun to 3,000 psi. Those vintage hand pumps could get as high as 1,000 psi in extreme cases, but then they took a very long time to fill the gun because they compressed so little air.
After Daystate broke the ice, the entire world got into PCPs. Shooters discovered how accurate they are and how easy to shoot. Shot after shot with no pumping, no cocking, nothing but loading and shooting. And, accuracy that surpasses a .22 rimfire out to 50 yards.
The big bore revival began in 1996
Dennis Quackenbush brought out his CO2-powered Brigand rifle in 1996. It shot a .375-caliber round ball and got 60-80 foot-pounds of energy. Accuracy was on the order of 5 shots in 1.5″ at 30 yards. Gary Barnes soon followed, and his early big bores were pushing the 250 foot-pound mark, with accuracy equivalent to Quackenbush. The Koreans saw a market and brought out the Fire 201 air shotgun with a 9mm rifle barrel. That gun got 150-175 foot-pounds and accuracy of 1″ at 40 yards. By now, the 21st century had started and the race for power was on!
The multi-stage hand pump debuted in the mid-90s
Fredrik Axelsson designed a multi-stage hand pump that could compress air to 3,000 psi for the European target shooters and the few sporter PCPs that existed. The name of the first company to market a hand pump was Axsor. Within a few years, Axelsson left Axsor and started another company called FX to make a different hand pump and several models of sporting PCPs. Hill of England came out with a completely different hand pump capable of achieving pressures up to 3,500 psi.
Before we move on, you should know something about the technology in one of these exotic hand pumps. They are actually a pump within a pump within a pump! That’s correct, there are actually three pumps nested inside what looks like a common bicycle pump. I have repaired many of these pumps, and they’re very complex inside. There are about 20 different-sized O-rings in one of them! And they generate great heat when they work – high enough to cause brass parts to fail if you don’t give them a break after five minutes of pumping. I own all three models – the Axsor, FX and Hill, and all my pumps still work perfectly after many years of service because I follow the manual’s recommendations. Yes, $200 is a lot of money, but not when you consider what you’re getting.
Incidentally, DB, a 3,000 psi 80-cubic-foot aluminum scuba tank sells new for around $150, so it doesn’t cost more than a hand pump. I have two tanks. I paid $20 at a garage sale for the last one and $100 for the one before that.
High-pressure electric compressors
You’ll pay $2,500 for a cheap electric compressor that will go to 3,000 psi, unless you buy the FX electric compressor. Yes, it does have the hand pump at its heart, but it is water-cooled for much greater longevity. As long as you don’t abuse it by filling scuba tanks, the FX compressor should last a long time.
“You can buy a really nice firearm for less than the cost of this gun and pump.”
Yes you can! You can also buy a nice lawnmower for less – so what? Neither one is a precharged air rifle. You don’t buy these things to save money – even though I hope that I’ve demonstrated you are now paying less than ever for this technology. Precharged air rifles are science experiments with practical applications. They aren’t firearms, nor should they be used as substitutes for them. Enjoy them for what they are.
What about the future?
I don’t see big bore prices coming down much. What I see is capability going up. Quackenbush now makes a big bore that delivers 1,000 foot-pounds, and Barnes does the same. The Korean guns are pushing past 300 foot-pounds. Smallbore repeaters are becoming more accurate and more reliable. A new hand-pump that is being developed will at least hold the price steady, regardless of where the Euro goes. Plus, there are several lower-priced electric compressors in development. Companies are working toward a target retail price of $600 for a portable electric compressor (the FX compressor is now at $1,200). If you’re interested in precharged airgunning, you’re in, what will someday be called, the Golden Age.
by B.B. Pelletier
You’re already on the internet, so I don’t have to tell you how good it is for finding facts. But, several of you have asked research-type questions, so today I thought I’d show you the mother lode of airguns links – AirgunInfo.com, hosted by Pyramyd Air!
Airgun forums and blogs
Last week, I answered a basic question about airgun forums. Well, there a whole section of the main page dedicated to them on this site. It’s on the left margin, and you click on the forum logos to connect. You’ll even find this blog there. Then, there’s a hot link under the General Info heading to lots more forums. It’s called airgun forums, logically enough. The coding has made most links open in a separate page, so you won’t lose your index page on Airgun Info. A few do not, however, so pay attention to what you are doing as you browse.
Classified ads and used guns!
You guys are always wanting to buy the neat collectible guns I show you here. Well, the classified ads are where to begin. I just spent 10 minutes there browsing the links and may have bought a bargain airgun book! Don’t forget, may of these classified sites give you free listings, so when it’s YOUR turn to sell, they are also great for that!
Besides the classifieds, there are also used gun sites. I would have thought Pyramyd would only have linked to their own used guns, but it looks like they got most everybody! I spotted one missing link, which I forwarded to them, but this is the best collection of used gun listings I have seen.
Repairs and parts!
We always need links to repair stations and parts suppliers. The Repairs and Parts page on this website is HUGE! This reference site must rank as one of the best if not THE very best airgun reference site on the internet. One word of caution on the repairs; some of these guys have not been around that long, so check references before sending off a treasured heirloom. If I tell you about someone in this blog, I have already checked out that person’s work. Not that I’m an authority, but I won’t recommend someone I know to be a fruitcake. On the other hand, anyone can hang out their shingle on the internet!
Almost all airgun manufacturers have some kind of website. The links for them are on the Manufacturers page. If you want to know what Baikal IMZ says about the airguns they make (like the all-black Drozd), check out their site! The manufacturers will also announce new products on their website (some of them, at least), so this becomes your window on the world of airguns.
Talk about Macy’s sending customers to Gimbels! Pyramyd Air has a page of Dealers. It worked in Miracle on 34th Street, and it works for Pyramyd Air for the same reason. For those who fly the Maple Leaf, there is an entire page devoted to Canadian Airgun Dealers. Customers know instinctively that when a dealer is willing to tell you about other dealers (to the point of telling you what they specialize in!), they are confident of their own position in the marketplace. Gimbel’s didn’t understand it in the movie and neither do most of the other airgun dealers.
For those who still can’t convert inch-pounds to Newton-meters in their head, there is a great Conversions web page. If you still haven’t found the energy conversion page on the Pyramyd site (despite the tons of bread crumbs I’ve been scattering), perhaps this page will be of some service.
And SO MUCH MORE!
There is so much on the Airgun Info site that I’m going to let you do your own exploring. When a new guy asks a question that you know is answered here, please refer him if you see the comment first. I think Pyramyd Air deserves our thanks for providing this wonderful reference for free. I’ve got it bookmarked on my “hot buttons” bar at the top of my browser. I suggest you do the same
by B.B. Pelletier
This one is for JW, who read the posting on cleaning airgun barrels and asked, “Okay B.B. You’re sure this is safe? My RWS owner’s manual says not to use brushes, but I’m assuming since I’m only doing it this once, it will not harm anything. By the way, I bought some cleaning pellets and shot a few through my RWS 34. I was amazed at how black they were. I’ve only shot about 250 pellets through it since I bought it new, so I’m assuming that it came from the factory like this. Is this typical for a new gun?”
Airgun barrels are made from soft steel or brass!
Soft steel abrades very fast, and brass abrades even faster. Incidentally, some of the airgun forums are talking about phosphor bronze barrels right now. The last use of phosphor bronze (and any other kind of bronze) was on the Sheridan Supergrade, whose production ended in 1954.
When you clean the bore of a gun, the cleaning rod can rub against the bore at the point where it enters the barrel. It will wear the barrel if it does rub. That’s why you are warned to clean a barrel from the breech, if possible, so you don’t wear the rifling at the muzzle.
To overcome this potential problem, cleaning rods are now sometimes rubber-coated for bore protection. The point is…don’t let the rod wear the bore by rubbing.
Flexible cleaning rods!
Some guns are constructed in such a way that a flexible cleaning rod or cable is the only way you can clean it from the breech. I use one when needed, but I’m very careful! Some of these flexible systems are potentially very hazardous to rifle barrels!
Several years ago, an airgun hobbyist was selling cleaning systems made from monofilament fishing line. The line was passed through the muzzle and out the breech of guns with sliding compression chambers, like the Diana RWS 52. It was looped to grab a cleaning patch and pull it back through the bore from breech to muzzle – just like the experts tell us. What they didn’t tell anyone was that if you got lazy and pulled from the side of the muzzle instead of straight, the monofilament line would cut through the steel on your barrel! If any of you are lapidaries, you can back me up on this. Don’t jade carvers use monofilament line coated with diamond dust to carve jade?
This same hobbyist was also selling green ScotchBrite scratch pad material as a bore cleaner! Folks, green ScotchBrite is so abrasive that it can remove the rifling from a steel barrel in a very short time. Many airgun manufacturers use it for final detail finishing before sending their parts out for bluing, annodizing or plating!
Use a brush that is softer than the barrel
I suspect that RWS warns against using brushes to clean their barrels because so many shooters are careless when they clean. If you do use a brush, use one made of a material that’s softer than the barrel of your airgun. For steel barrels, a bronze brush is fine. For brass barrels, there are nylon brushes, though I feel you should stay out of a brass barrel altogether unless there is a real problem.
The cleaning procedure I outlined in the linked article is recognized by all the major firearm and airgun manufacturers in the world. You only do it when there is a problem with accuracy – not after every firing.
Felt cleaning pellets
Felt cleaning pellets should not be used in a spring-piston gun. They do not cushion the piston sufficiently, and it is akin to dry-firing. You can use them in just about every other powerplant. If you do use them, pack in enough pellets to provide some resistance when the piston comes forward. For a gun with the power of a Diana RWS 34, perhaps five cleaning pellets in a row might be enough to cushion the piston.
The black stuff JW mentions seeing on his felt cleaning pellets is the graphite anti-oxidant coating found on some pellets so they don’t turn into white dust in six months. It does not harm the gun, and it keeps getting removed and redeposited as you continue to shoot.
If I make it sound as though the barrel on you airgun is fragile, don’t fret. It really isn’t that bad. With a little common sense, you can keep an airgun barrel working well for longer than a lifetime.
by B.B. Pelletier
A lot of you like to hunt with your airguns. I’d like to show you a carbine that’s a hunter’s dream – the Career Carbine in .25 caliber! (Scroll to the bottom of the page to see specs & prices.)
The Career 707 Carbine is a trim little rifle with a BIG PUNCH! In .25 caliber, it will roll the largest airgun game.
The Career 707 was one of the first powerful Korean repeaters to come to this country. It has been a huge success, mostly due to the smashing power the rifle develops. In fact, it’s so powerful that Americans were asking for modifications to LOWER the power before the first year of importation was up (1995). That’s a switch! The big plus with a Career is the accuracy. These rifles can deliver sub-1″ groups at 50 yds. and still deliver the same muzzle energy as a .22 short!
The Career Carbine came several years after the rifle. It has the same general appearance as the rifle, but the shorter length makes it lighter and faster in the woods. You will lose some shots due to a smaller reservoir, and the power is not as great as the rifle, but the Career Carbine is still a very powerful air rifle! Instead of 70 foot-pounds, you’re down somewhere in the 50s. Big deal! The woodchucks won’t know the difference.
The Carbine is also a loud airgun. It has to be with that much air coming out of a short barrel. If you decide to buy one, do so for the convenience of a small handy carbine that still exceeds the power of most European airguns. Because you will shoot diabolo pellets, you will have the same safety range as lesser air rifles. I’ll make pellet recommendations in a moment, but there’s one more thing I want you to think about.
The Career Carbine in .25 caliber!
As long as we’re going big today, why not go all the way and get a .25 caliber carbine? While I was looking through the pages on the Pyramyd Air website, I noticed how difficult it is to find the Career Carbine. Then, I noticed a sale on the .25 caliber Career Carbines. Do you know what a great deal this is?
I think that airgunners sometimes order a carbine without knowing how powerful it will be. Maybe they’re shooting an RWS Diana 52 at present and this little carbine that weighs LESS THAN 7 LBS. is MORE THAN TWICE AS POWERFUL as their rifle. They don’t stop to consider how the Carbine accomplishes that. It does it with a lot of compressed air, and the muzzle blast reflects it. If you’re prepared for the sound of a .22 rimfire, the carbine sounds nice. If you compare it to a spring rifle, it will assault your senses.
Today’s Career has an adjustable pellet feed, so the gun can adapt to long or short pellets. My No. 1 pick is the 36.6/36.8-grain super-heavy Eun Jin pellet. Yes, they’re expensive compared to smaller-caliber pellets, but this is a hunting rifle we’re talking about, and these pellets really reach out and do the job. Never scrimp when it comes to ammunition for hunting! My second choice is the (almost) 31-grain extra-heavy Beeman Kodiak pellet. In fact, try both pellets in your gun to see which is the best. Some guns shoot the Kodiak better than the Eun Jin.
Two more pellets
I know from experience that the 21-grain Diana Magnum pellet is very accurate in other .25 caliber airguns, so give it a try in the Carbine. It’s lightweight (imagine 21 grains being called light!), so you’ll get more velocity to reach out farther and flatter for squirrels and rabbits. The H&N Field & Target pellet also looks good. At 24.4 grains, it’s a medium-weight pellet in this caliber.
If you use a scope, you’ve GOTTA pick the new Leapers 6x Bug Buster. It’s built on Leapers new TS super-strong platform and has more power than ever – yet it’s sized perfectly for the Career Carbine. The article I linked to is about a different TS scope, so don’t be confused by the slightly different appearance.
The bottom line for the Career Carbine is this – it’s not for everyone. But, for hunters, it’s a good ‘un. If you hunt where light weight and small size are important, this one might be for you.
by B.B. Pelletier
This topic was suggested by a flurry of questions about dieseling that we received just after the new year began. I thought I’d take some time to explain what we believe goes on in the spring-piston powerplant when it fires.
This book is a standard airgun reference. It’s hard to find. However, you might find one at an airgun show.
The standard reference
For airgun operation, especially spring-piston guns, The Airgun from Trigger to Target by G.V. and G.M. Cardew is the source of most of what is known. The Cardews did extensive research and experimentation in this field, and they published the complete results, including their test designs. So, if someone doubts what they say, he knows where to begin if he wants to prove them wrong. To date, very few have taken up the challenge.
Four phases of spring-piston guns
The four “phases” refers to how much velocity is generated and also how that velocity is obtained. The phases are:
This is the weakest of all spring-piston guns. The powerplant doesn’t generate much compressed air, and the loose-fitting projectile doesn’t make good use of what there is. The Marksman 2000K pistol is a modern example of a blowpipe gun, though there have been numerous other exapmles throughout history. The “Gat” pistols are another example, as is the vintage Quackenbush line of airguns (not the big bores made today by Dennis Quackenbush). The blowpipe is really just a mechanical device that emulates a common pea-shooter or blowgun.
The popgun phase begins when there is more compressed air, but it doesn’t generate enough heat for combustion. The pellet fits the bore tightly and makes maximum use of the air pressure. Though the name sounds degrading, all the spring-piston target rifles and some of the pistols are actually popguns. The FWB 300 rifle generates velocities of less than 550 f.p.s. in .177. Since there is no combustion (I will address this in a moment), the popgun is usually the most well-regulated of all spring-piston guns, not varying in velocity by more than a few feet per second. The IZH 53M is a good example of a modern popgun pistol, while the IZH 61 is an example of a popgun rifle.
This is the phase that almost all adult sporting airguns are in. When the piston compresses the air, the heat it generates is so high that it ignites any small droplets of lubricants that may be present in the compression chamber. What the Cardews proved by their testing is that all powerful spring-piston guns burn fuel to generate their power. The power that’s added by combustion depends on the amount and combustion quality of fuel available. This is where some badly-tuned spring guns shoot at all different velocities. Ten years ago, I was advised by the importer of some Chinese air rifles to liberally lubricate the compression chamber with corn oil. He said the wax in the oil would leave deposits on the walls of the compression chamber and make the piston seal fit tighter, raising velocity. In fact, the corn oil was a very good fuel! The treated guns jumped by 100 f.p.s., or so. [I bet I've just started a race to the kitchen to "borrow" the Wesson Oil!]
The Cardews maintain that all powerful spring-piston airguns are in the combustion phase. They also say that isn’t a bad thing. As long as the combustion is controlled and small, it benefits us all. In other words – all guns diesel. But when it gets out of hand, we move up to the next and final phase.
This is the phase you DON’T want to be in! An abundance of fuel in the compression chamber no longer burns – it explodes! You get much higher velocities out the muzzle – and broken mainsprings, swollen compression chambers and guns that sometimes actually re-cock themselves at the other end! All combustion-phase airguns are capable of detonating, so the shooter has to severely limit any fuel-like substance that is introduced into the compression chamber.
When you hear a loud BANG! and sometimes see a bright light coming from the muzzle (flames in the barrel!), you have a detonation. Since all combustion-phase guns can detonate, the thing to do is to reduce the number of detonations to as few as possible. Just having smoke in the barrel is not a detonation, but the byproduct of a normal combustion. BB guns are the biggest combustors of all, but almost all pellet rifles and many powerful pistols are also combustors.
You’ll have to get the Cardew book to read about their experiments. It’s also a good reference book for anyone who wants to know more about airguns.
by B.B. Pelletier
We got this comment last week, and I promised an answer as a complete posting because this one will take some time. Butzback asks, “How does the Gamo compare to a Beeman? The Beeman is so much more expensive [that] it makes me wonder about quality, performance etc.” Let’s get to it!
First we do Gamo
Gamo is a company that dates back to 1889, when they were founded to produce high-quality lead.In 1950, the company decided to start production of lead pellets to satisfy the growing demand in Europe. In 1961, Gamo introduced their first airguns to the Spanish market. Today, they are the largest airgun maker in Europe.
Gamo guns have been coming into this country since the early 1960s. Their models have always been different and innovative. The Expomatic was a repeating diabolo pellet rifle, made at a time when pellet repeaters were not well-known. Gamo guns today range from youth models to the extremely powerful Hunter 1250 Hurricane. Most of their rifles have been springers, which is what I will concentrate on in this posting. However, they’re also a leader in CO2, and they’ve built a few single-stroke pneumatics. The big rumor on the street is that they’ll soon offer a precharged rifle. Because they own BSA, who already knows precharged technology, they have access to those designs. They’re also supposed to be working on a new type of hand pump, which should hit the market when and if a PCP comes out.
All Gamo spring rifle models are different, but they do share some common characteristics. The dry-fire capability we discussed last week is one of those, as is the Gamo trigger. The trigger starts out as a very stiff and creepy unit with an ambiguous release point. However, the more you shoot the gun, the better this trigger gets. There have been other airguns with this same characteristic – notably the BSF spring guns from Erlangen, Germany, and many of the Webley rifles of the 1980s and ’90s. I’ve shot a Gamo Hunter 440 with 6,000 shots on the trigger, and it was as smooth and predictable as most spring gun triggers – certainly as good as an RWS trigger.
Moving on to Beeman
Unlike Gamo, Beeman doesn’t make airguns. They are an importer that puts their name on models they decide to sell. When Robert Beeman headed the company, he carefully built a reputation of quality and performance that American shooters had never dreamed possible. Since selling the company in 1994, there have been major changes to the quality of the guns that carry the Beeman name. In the beginning, this was limited to the trimming of certain low-sales guns like the HW 55, but as time passed, the Beeman company grew more “corporate” and lost some touch with its roots. They stopped publishing the full-color catalogs Robert Beeman used to build the company’s reputation. They are closely associated with Marksman, an American maker of inexpensive, mass-marketed airguns and have had ties for a long time to large retail outlets such as Wal-Mart. Both companies are owned by SR Industries.
A marketing move to extend sales for Beeman was to take Spanish airguns made by Norika and put the Beeman name on them. When Robert Beeman owned the company, they carried a few Norika guns, but Beeman never put his name on them – just as he never put his name on the Yewha shotgun, the S&W pistols or the Sheridan Blue Streak. But, now, it’s possible to see Beeman air rifles in Wal-Mart. This has diluted the Beeman name somewhat. It no longer conveys quite the panache that it did when the founder was at the helm.
The bottom line
Because of this situation, you see how difficult it is to write about the quality of a Beeman airgun. They’re all over the place! The R-series rifles are made by Weihrauch and are as good as they ever were, but there are increasingly cheaper guns carrying the Beeman name today. So, there is no such thing as “Beeman quality” any longer. To talk about Beeman air rifles, you must pick a model and get specific.
The answer. I hope!
Now, butzback, I’m going to assume that you were referring to the R-series rifles when you asked your question. How do THEY rate against Gamo air rifles? They are better in the following areas. They have a much better and more adjustable trigger. They have a better (well-rifled and uniform) barrel, as a rule, and they can out-group the Gamo rifles. HOWEVER, all companies have good and bad days. On a bad day for Weihrauch, their barrel is not going to be as good as a good Gamo barrel. In other words, there are exceptions to what I say about barrels. The Beeman (not Weihrauch, but Beeman R-series) stocks are better shaped and generally nicer in form and feel. The Beeman R-series powerplants CAN be better, but this is an area in which Gamo is rapidly closing the gap, in my opinion. And, Weihrauch is slipping just a little at the same time.
Everything I said in the paragraph above IS JUST MY OPINION. I can’t back up any of it without sitting down face-to-face with someone and comparing two rifles side by side. That would involve shooting as well as a physical examination. So, this opinion is worth about what it costs. Take what I say and evaluate the guns for yourself.
by B.B. Pelletier
I don’t know where this question came from, but it’s been weighing on my mind for many days. I thought it was in a comment to this blog, but it could just as easily have been a topic on one of the airgun forums. I want to address it because it gets down to the fundamentals of the shooting sports.
More power – Tim Allen got it right!
Tim Allen’s famous monolog in which he pokes fun at the male lust for more power had a profound message. As he skillfully points out, more power is not always the answer – or even a good idea! Take the Boss Hog motorcycle, for instance. It’s a motorcycle built to accept a large-displacement Chevy V8 engine that develops over 500 horsepower! It’s the very parody of a motorcycle! It isn’t faster than other bikes, it doesn’t accelerate quicker and it certainly doesn’t handle as well as a hundred other conventional motorcycles. Yet, I want one. To be astride such a beast is to have the biggest, baddest ride in town – as long as Jay Leno doesn’t ride up on his motorcycle, which has a 1,500-horsepower helicopter turbine engine!
It’s purple and $32,000 in the standard version. Totally useless. Yet, I want one!
Consider the absurdity of the question
If more was always better, why don’t sports cars have six wheels instead of four? Why aren’t handgun calibers made larger every year? Uh, oh! I forgot. They are! Enter the S&W .500 Magnum revolver – breakfast of complete fools who can’t wait for the world to know it. A revolver caliber so powerful that the average used one has fired less than one box of ammo – usually just five rounds (one cylinder full). Nevertheless, this gun sells very well. Good for S&W – not so good for those who have no idea what they’re getting into until the hammer drops the first time! More is not ALWAYS better.
Joking aside, there are lots of things that are just as useless. We have advertising to thank for that. Advertising tells us so often that “MORE IS BETTER” that we’ve come to believe it. Which takes us to today’s topic: Are more rifling grooves better (more accurate) than less?
In rifle barrels, the number of lands and grooves MAKES ABSOLUTELY NO DIFFERENCE, as far as accuracy is concerned. That’s assuming that the minimum number of lands and grooves is adequate to stabilize the bullet/pellet. In World War II, the U.S. Army proved that two lands and grooves were enough to stabilize a 150-grain bullet in a .30/06 rifle. They accepted two-groove barrels in their Springfield 03A3 rifles because they could be produced faster than four-groove barrels (the previous standard), and faster production during a war is good. The decision-makers admitted that these rifle barrels were not absolutely the most accurate they could produce, but the four-groove barrels they replaced were no more accurate, so who cared?
What makes a barrel accurate?
The most important factors for a barrel to be accurate, according to Dr. F.W. Mann, who did 38 years of research on the subject, are straightness, uniformity of the bore and rifling, twist rate matched to bullet length and velocity (not as much for pellet guns, because we use high-drag diabolos instead of bullets), a choked muzzle and a uniform forcing cone with graduated rifling (called a leade) at the end of the chamber. Dr. Mann used barrels from several makers, but he did his best work with barrels handmade by legendary barrelmaker Harry M.Pope. Once he figured things out, Pope always used eight shallow lands in a lefthand twist. He often used a gain twist (one that gets faster) but not always. He always choked his muzzles by a half-thousandth. Many of his rifles were meant to be loaded at the muzzle, which would seem to negate the choke, but the heavy smack delivered by the explosion of the black powder charge bumped the bullet, squashing it at the base to fit the bore tightly.
Dr. Mann wrote his findings in his book, The Bullet’s Flight From Powder to Target. This book is a classic and is still considered to be the best and most fundamental reference book on rifle accuracy, even though it was initially published in 1909, after 38 years of experimentation. Today’s best gun writers have this book in their libraries to fully understand the complex, yet unchanging principles that govern the ballistic projectile we call a bullet.
Dr. Mann And Harry Pope both knew that the uniformity of the base of the bullet was extremely important to accuracy. That’s why Pope rifling was as shallow as it was and why he used eight lands and no more. He found that each land put a burr on the base of the bullet that interacted with the gasses exiting the muzzle at high speed. This destabilized the bullet by a small but measurable degree. Dr. Mann provided the measurement. That’s why the most accurate Pope barrels were muzzleloaders, even though they used cartridges loaded from the breech. By loading the bullet from the muzzle, the small burr would be on the front of the bullet, where Dr. Mann demonstrated almost no amount of mutilation had any effect on accuracy. You could say that Harry Pope perfected the microgrooved barrel, but Marlin was the company that coined the term.
The bottom line is this: the number of lands and grooves has no effect on the accuracy of a rifle barrel. Microgroove rifling can be beneficial, but only if all the other important factors are also correct.