Also, the collective information as to the internal dimensions of revolvers, i.e., their dynamics, has been expanded to areas not many shooters have investigated, either because they didnt know about them, or they just didnt care. As long as most of the shots hit where they were supposed to things were left alone. But what if they could be improved? What if a somewhat faulty set of dimensions or a rough bore of a revolver or auto pistol could be altered by the shooter to improve accuracy?
To that end we acquired a kit from Beartooth Bullets, P.O. Box 491, Dover, Idaho 83825, (208) 437-1865 (or at beartoothbullets.com, $49 plus shipping & handling). The kit included a box of 100 lapping bullets in your choice of caliber, two steel plates, a four-ounce can of lapping compound, a huge bolt that fits into your loading press where the dies screw in, and a technical manual (mailed separately). The manual was called Technical Guide, and was written by Beartooth headman J. Marshall Stanton in clear, unambiguous English, which was a revelation after having struggled through the somewhat foggy NECO manual. The subtitle for this manual is, A Comprehensive Guide For Attaining Unsurpassed Performance Using Cast Bullets. Sold separately for $15, the manual goes into great detail on how to do just that.
We had been working with several revolvers that shared the same problem. The barrel was too tight where it was screwed into the receiver. This area often gets compressed from normal assembly, resulting in a choke that pinches or resizes the bullet. The gun cant shoot its best because the bullet is now too small for optimum contact with the rifling during the rest of its passage through the barrel. While this can happen to both cast and jacketed bullets, and holds true for rifles as well as handguns, we will concern ourselves in this report with cast bullets fired from one revolver and one 1911 pistol, both of 45 caliber. The revolver was a Cabelas (Uberti) 4.6-inch barrel in 45 LC, and the 45 auto was the recently tested Taurus PT-1911, which had a strong tendency to collect lead.
Preparations
Before beginning any firelapping efforts we strongly recommend reading at least the entire chapter on firelapping in the Technical Guide. If you never firelap anything, youll still appreciate the wealth of knowledge in this little 106-page book, as well as the note-keeping suggestions to clarify and ease all your shooting efforts.
In the Beartooth process only one size grit lapping compound was used, (320 grit, available from several sources, including Beartooth). NECO had you start with 220 and progress through several finer grits. Weve now learned thats not necessary, though some might argue this point. First, the barrel must be rendered absolutely clean of all lead. The manual offers several ways to do this, but for us, the best was the simplest. Go to your grocery store and buy a copper (not stainless steel) scrub pad, pull it apart and cut suitable lengths of it to wrap around an old bristle brush. Make sure this fits tightly in the bore, and itll quickly remove any and all leading.
Next, get fifty fired cases, preferably ones that were fired in the gun youre working on. Be sure to record or save targets before you begin any lapping so you have something to compare to your final results. Decap, but do not resize, those 50 fired cases. Chamfer the mouths to ease the seating of the oversize, grit-charged bullets that youre going to fire through the gun. We used a power drill and a countersink to very quickly process all 50 cases. Actually, for two calibers, we did 100 cases. It took only minutes.
Next prime the cases and stand them in a loading block. We used CCI 300 large pistol primers for all our efforts in both calibers. The lapping bullets were cast bullets that had not been sized or lubricated. They were soft and oversize for the caliber. Lapping bullets in calibers 22 to 40 cost $15 per 100. Calibers 41 through 50 cost $17. Shipping was extra. The best ship deal is $14 flat rate for 3-10 boxes of bullets, plus $2.50 handling fee.
Oversize bullets are mandatory for this process. A revolvers chamber throats (cylinder outlets) have to be larger than the groove diameter or the process simply wont work. All youll end up doing is wearing down the tops of the lands and basically removing the rifling from your gun. If the throats are too small, the lapping bullets will be sized to the cylinder throat diameter before they enter the barrel. That means they wont touch the bottom of the grooves firmly and uniformly.
What to do if the chamber throats are too small? We had that situation with a Ruger 44 Magnum. Its cylinder throats were one-thousandth inch too small. We purchased a reamer from KBC Tools & Machinery (KBCTools.com) that was one-thousandth inch larger than the groove diameter and opened up the throats. Be sure to read the Beartooth manual for their recommended throat size for a given caliber. Theres also a method detailed to wear the throats larger with sandpaper. We prefer the precision of a reamer, which was not very costly, in our opinion ($22 plus shipping), especially in light of the time saved over the sandpaper method. KBC has a selection of chucking reamers on hand in steps of one-thousandth inch in a range of sizes that apply to cylinder reaming.
So now weve got a supply of lapping bullets, we know the revolvers cylinder throats are larger than the groove diameter, and we know theres a tight or rough spot or two inside the bore. We found that out by slugging the bore with a lead ball. We used Speer swaged pure lead balls designed for muzzle-loading handguns to do our slugging. Another method is to use fishing sinkers. Slugging is easy. With the bore absolutely free of all lead and other fouling, lightly oil it. We used WD-40. We suggest securing the gun in a padded vise with support so it wont slip. Then hammer one of the pure-lead balls into the muzzle with a suitable non-marring hammer. Then use a brass rod (never steel) nearly as big as the bore diameter to tap or press the ball through the bore.
If at all possible, push the slugging bullet through by hand so you can feel the loose and tight spots. With most modern revolvers well guarantee youll hit a lot of resistance when the lead ball gets to the area where the barrel was screwed into the frame. If in doubt, slug it again. Try to get a feel for what youre going to be working on. What we want ultimately is for the ball to push through absolutely smoothly, with even resistance. Through proper firelapping the bore will end up with a very slight taper of about half of one-thousandth inch from the breech to the muzzle.
Charging The Bullets
The next step is to embed the lapping bullets with the lapping compound. Wearing protective gloves we began the process by putting a good dollop of lapping compound on the steel plates and rolled each and every bullet firmly between the two plates. We were generous with the lapping compound, and made sure some remained in the groove of the lapping bullets. This was a messy, thankless, and seemingly endless task.
With a stack of messy, gooey, grit-encrusted bullets it was time to charge the cases with powder. We tried Bullseye and Trail Boss powders, and weve come to prefer Trail Boss. The idea is to just barely get those bullets out the bore. The tech manual says repeatedly what you want is air gun velocity, but thats a mistake. Our air gun puts pellets out at over 1100 fps. What you want is 400 to 500 fps, very slow velocity. To give you some idea, we used 1.2 grains of Trail Boss in our Taurus 1911. The result was a pop, but no stuck bullets. We suggest you not take that as gospel, but decrease the charge from a higher number until you get a suitable low velocity. When loading for a revolver keep in mind that the cylinder-to-barrel gap will allow some gas to escape. Loading for our 45LC revolver we had to go a little hotter on the powder charge. We used around 3 grains of Bullseye, but could have gone lighter. Your system may vary. The trick is to keep the velocity low but generate enough pressure (propulsion) so that the bullets wont get stuck inside the bore. If you stick one, the Technical Guide has a great system for getting the bullet out. We managed to stick several in the Cabelas, and the system described in the book got them out easily with no bore damage.
Now, whats that big bolt for? Use it in your loading press as the seating die for the gooey, grit-charged bullets so you dont mess up your normal seating die. The big bolt lets you see what youre doing as the bullet is seated. Seating bullets was another mess, because they were well loaded with lapping compound. You need to get all of the charged surface inside the brass case. Youll be glad you chamfered those cases.
Once your lapping bullets are all loaded, wipe off all of the residual compound, especially from the brass cases. The key is to keep the grit out of your chambers to avoid them being scratched. Next, load six of your lapping loads into a perfectly clean, lightly lubed (we used WD-40 again) barrel and shoot em. Be sure to feel the recoil as each bullet leaves the gun, or shoot into something that indicates a bullet strike. Dont try for accuracy. Six visible hits on target are better than one ragged hole. This is VITAL. You dont want to stick one in the barrel and fire another slug on top of it. Next, clean the barrel completely. Here is where that trick with the copper pad will come in handy. Be sure to also clean the chambers because the grit tends to get blown back into them from the light loads. Lightly lube the bore again and shoot six more.
The Beartooth book does not specifically recommend using any lube before firing, but we have found that WD-40 is a fine honing tool on whetstones and we thought it would aid the cutting of the bore. This might have been a mistake, and might have thus taken more lapping loads, but thats what we did. However, in the Beartooth archives was a report by a fellow who cleaned the bore diligently and vigorously, and left the cleaning solvent in before shooting again. It cut his work down significantly, and thats why we did it our way.
Heres what we did with each gun.
Cabelas 45 LC
The first step was to slug the clean bore and measure it. Next we used a machinists expanding ball and a micrometer to measure the cylinder throats and found them to be irregular. We could have shoved lead balls through the cylinders if we didnt have the expanding ball tool. We used a 0.455 reamer to open the six throats to uniform dimensions. That was a bit larger than needed. The bore measured 0.451 inch. We then cleaned the barrel of all lead and shot two control targets of 10 rounds each, and saved the targets. The 10-shot groups measured 2.7 and 3.8 inches, and had numerous flyers.
We noted after the first six lapping rounds there was almost no apparent leading. The bore cleaned easily and the shooting went quickly. After 18 rounds the tightness was still there, so we proceeded to fire all 50 lapping rounds. After that, we still could feel the restriction at the threads. Accordingly, we prepared 50 more firelap rounds and fired them. We thought we were done, as we could barely feel the restriction of the threads. We then proceeded with the remaining instructions, which were to polish the bore with 100 strokes of a cloth lap charged with the lapping compound. Then we broke in the essentially new barrel with 29 shots, cleaning after each shot for five, each three for three times, and after each five for three times. We then tried the control load again, firing two groups of ten shots each. The results were disheartening. The group sizes were smaller.
We thought the problem was too-soft bullets, so in desperation we cast some fresh Keith-form 260-grain bullets and dropped them into water, to make sure they were hard. We sized these bullets to 0.454 inches. This was tight for the bore, which slugged to 0.451, but was close to the recommendations of Beartooth Bullets, which wants them the size of the cylinder throats, now 0.455 inch. We fired our hard-cast bullets with 5 grains of Bullseye and with 10 grains of Unique. Our results were even more discouraging. Our best group with 10.0 Unique was 2.5 inches in a round pattern.
The problem was that the barrel still had significant tightness at the threads. Accordingly, we lapped it 50 more rounds, for a total of 150. After that we felt a big improvement in the evenness of the pressure required to shove the slug through the bore. We then prepared and fired 50 more, which brought our total up to 200 lapping rounds. At the end of this, we thoroughly cleaned the barrel, lightly lubed it and shoved through a lapping slug. Finally we had achieved what we set out to do. There was no more constriction at the thread area.
We tried the gun with our control load, and put five shots into 1.7 inches with four of them cutting a ragged hole measuring 0.7 inch center to center. We noticed some leading, so again cleaned the bore totally and loaded up a light handload with bullets sized exactly to the groove diameter of 0.451 inch. These cut a basically round group measuring 1.9 inch center to center, and gave exactly no leading. We then fired 10 shots using a commercially cast bullets of 0.453-inch diameter, and put 10 into a group that measured 2.0 inches. This group compared most favorably with the before 10-shot groups that were 2.7 inches and 3.8 inches wide center to center.
Any time you shoot oversize bullets in a revolver youre going to raise pressure over the same powder charge with correct-size bullets. Said another way, with a given constant amount of powder, the pressure you get with groove-size bullets will be less than the pressure you get when you shoot bullets that are larger than the groove diameter. Elmer Keith documented this many years ago with the help of professional pressure-measuring services. Keith always recommended groove-size bullets, never larger. He also noted that the rear end of cast bullets would upset to fill the throat with heavy loads, and would then size down again to the original diameter when the rear of the bullet squeezed into the forcing cone. Keith was working with full-charge loads, so there was no room for error in terms of pressure, which is why we mention this. With midrange loads you might not notice any pressure increase unless you chronograph your loads. But if you push things, as many do with todays fine crop of 45 LC handguns, youd better be careful.
We have some more shooting tests to do with the Cabelas 45, including testing the theory that we should shoot 0.455 bullets for best results in our 0.451-groove handgun. For now, were satisfied with what we have achieved. The tightness at the threads is gone, the bore is slick as can be, and any traces of lead come out very easily. We had to shoot 200 lapping rounds, but compared with getting a new gun the cost was minimal. The result was a greatly improved handgun.
Taurus PT-1911
Prior to our firelapping work the stainless steel barrel of our Taurus pistol quickly amassed a heavy coating of lead. Beartooth warned that stainless barrels can be difficult to lap, and may require many more rounds than carbon-steel barrels. Such was the case with our Taurus. Unfortunately we measured the initial slug with a dial caliper that was not zeroed, and obtained incorrect readings. We thought the bore was just under 0.451 inch, but the groove diameter was actually closer to 0.453 inch, way too large for our cast bullets. If we had known the true dimensions of the Taurus barrel we would not have proceeded with this work, because there are no jacketed bullets commonly available for 1911s in that size. Most are 0.450 inch to 0.451 inch. However, we accomplished much of what we set out to do and found the perfect solution for the Taurus. Here are the details.
The very first thing we did was to deburr all the razor-sharp corners of this otherwise decent handgun. We used a machinists scraper, stones and files, and got the gun to the point where it would not hurt our hands during the course of our work. All told, that was a big job.
We found a tight spot inside the barrel of our PT1911 at the area where the locking lugs were cut into the barrel. Weve found this to be a common problem in low-end 1911 barrels. The result was that we experienced heavy leading after firing just a few rounds of our modest 200-grain SWC cast-bullet handload.
During our initial slugging, from the muzzle end rearward, we found the barrel had a really loose area in about the middle two or more inches of its length. The lead slug essentially fell through this section. Then there was a tight spot, as noted, around the location of the forward locking lug. So any bullet shot through the barrel would first get sized down by the constriction and then would rattle down the bore through the loose area, leaking gas all the time, until near the muzzle it would again be gripped firmly by the rifling. Thats assuming the bullet was initially the correct size. But we were firing 0.451-inch cast bullets in a 0.453-inch bore, so they just rattled down the bore leaving behind some of their composition, which was made worse by hot gas escaping past the loose bullet. Unless we fire cast bullets of 0.453 inch in that bore well never get good accuracy. However, we pressed on in ignorance, judging our progress mostly by the feel of the bullet sliding through the bore.
We began with 30 rounds and then slugged the bore again to get a feel for what we were getting. We proceeded to 50 rounds. At that point the sticky spot had diminished to some extent. We fired the gun with our handload and found the leading was reduced, but still evident. The barrel was easier to clean, because of its newfound slickness but accuracy was not much better. We continued with 50 more shots, for a total of 100 rounds. At 100 rounds we measured everything again. The faulty calibers read the bore at about 0.451. The tight spot was still prominent, though the transition from the loose section in the middle of the barrel was diminished. We could tell we were making progress, but we werent done yet.
We proceeded to fire another 50 rounds, for a total of 150. At that time the sticky spot at the forward locking lug was barely noticeable, but still apparent.
Using the dial caliper, we found the groove diameter at the muzzle was 0.4515 to 0.4517 inch, which was slightly oval. As closely as we could measure the reading at the breech was 0.4517 to 0.452 inch. Working the slug we could feel by hand more than we could see by eye on our instruments that there was still a slight restriction near the breech with a somewhat loose area towards the middle. It was also snug at the muzzle. We concluded that more lapping was in order.
Next, we double checked our results with a properly calibrated micrometer and got a huge surprise. The bore was just over 0.453 inch at the muzzle. The smallest groove dimension was a touch smaller than the muzzle at the tight spot near the breech, right at 0.453 inch. We slugged the barrel three times and used two micrometers to make sure our readings were in fact correct, because we have never seen a 1911 barrel that big. That big bore explained a whole bunch of our problems with the gun and its results on paper. On our test targets we commonly got three or four rounds grouping fairly tight, but there were always flyers that we could not explain. Once we knew the bores true dimensions the flyers were easily explained. The bullets did not fit the barrel.
Our firelapping removed less than a thousandth of an inch, so we hadnt enlarged the barrel. But, we had succeeded in slicking up the bore so it looked like a mirror. It was still leading but it was now much easier to clean. Accuracy wont be ideal until we acquire some cast bullets of the correct size, and we can still feel the tight spot, so more firelapping would be in order. Our work had done some significant leveling of the insides of the Taurus barrel, but the tight spot was still there. We recalled what Beartooth said about stainless barrels. We guess it would take at least 100 more firelap rounds to level the barrel and complete the task. But, then wed have a barrel of close to 0.454 inch at the breech, more like the dimensions for an antique Colt SAA than a modern 1911.
Despite the wrong-size bullets and the oversize bore, we test fired the Taurus with our handload. Before any lapping, our groups were badly strung vertically. The first five from a clean barrel had a center-to-center distance (five shots) of 1.9 inch. The next five, with a leaded bore, went 2.7 inch. After 150 rounds of firelapping, our two five-shot groups measured 1.7 inch and 1.9 inch. Clearly there was an advantage even though we are not quite done with the process, and the bullets were a poor fit in the bore.
We then tried one final trick with the Taurus PT-1911. We put a good Colt barrel into the gun with no other changes and shot several groups. With the Colt barrel in place all the bullets went into one hole. The conclusion seems obvious. The Taurus barrel is just plain lousy, and no amount of firelapping will make it into a precision barrel. If we continue to lap it well end up with a smooth, evenly tapered but way oversized barrel. (Which it actually what it was from the get-go). If you, the buyer, go to the trouble to firelap your barrel around 250 rounds, maybe more, youll be out the significant expense of lapping bullets, primers and powder, and enormous amounts of time and energy. Whats your time worth? We believe this Taurus has a sub-standard barrel, at least for the use of cast bullets. Instead of messing with firelapping, we could have stuck in a suitable replacement barrel of high quality. A really good aftermarket barrel will set the buyer back about $200. If we owned this gun wed find a good used barrel, or off-brand new one, stick it in there, and save the cost, time, and trouble of any more firelapping.
Gun Tests Grade: A-
We conclude that firelapping will unquestionably slick up your guns barrel and will generally improve handgun accuracy to some extent even with a sub-standard barrel such as was found in the Taurus. It will also make it easy to remove lead buildup and in general will vastly reduce accumulation. The bores of each of our test guns now look like mirrors. The cost of the process is not at all bad, and once you have the kit you can do any number of other guns by simply buying, or casting your own, lapping bullets of suitable size. We found the process to be time intensive, having spent more time on firelapping over the preceding month by far than we generally spend on a typical comparison test. We had to cast bullets, size and lube them, prepare the guns, prepare the cases, reload nearly 600 rounds including lapping and accuracy test loads, clean the guns repeatedly, trouble shoot them, make tools to remove stuck bullets, repair a troublesome sight on the Taurus, evaluate what we were getting, shoot test groups, and on and on. And were not done yet!
We have yet to try this process on a suitable 22 LR weapon, either handgun or rifle. Also, we have on hand a big new test rifle with a bore that seems to catch more than its share of jacketed-bullet fouling. We believe some firelapping will improve the barrel at least from the standpoint of easier cleaning. We hope to report on these applications in the near future.
Meantime, weve learned a whole lot more about what the proper dimensions of various handguns ought to be, and weve also learned they might not be what you think they are. Therein lies the key to accuracy when working with cast bullets. GT
Written and photographed by Ray Ordorica, using evaluations from Gun Tests team testers.
