This video shows the process of cut-rifled barrel-making by one of the world's best barrel manufacturers. Grooves: Round bottom CUT rifling . due to the superior throughput of hammer forging and button rifling. 30 cal, say 1 in 10, 11 or 12" (if you offer one of each), you’ll need a mandrel appropriate to each. We pay $125 more for a cut rifled blank so we charge $125 more for it. I have a late Remington SBL and a Ruger SBL and at the range they shoot neck and neck. might as well throw canted lands and button/cut rifling into the mix. So, on a . " You usually will find a. Didn't copper foul at all. Rifling begins by mounting the barrel in the machine and setting the desired direction and rate of twist. Cut rifling and broach rifling both involve removing metal from the inside of the barrel, which produces “grooves” that lie in between uncut areas know as “lands. Make sure to wipe down both the barrel and the tool with a clean rag to remove any residue. Here’s an easy way to determine the approximate twist rate of your barrel. . 16530 posts · Joined 2000. 280 posts · Joined 2017. Both methods can make junk or make match winning barrels. The cutter makes a full length pass in the direction the bullet travels and the machine indexes to the next point to cut the next groove. Start by cleaning all of the parts of the rifling cutter, using a cloth and lubricant. 35 Remington microgroove rifled barrel. See the figure below. It takes a LOT of effort to pull a . This method is used on most high-precision target barrels. 005 to . Cut rifling, yes, it makes one cut per groove at . Stone of Robbins & Lawrence created a rifling machine for carving out the barrels of guns, in particular the foreign-designed Enfield Rifles. 016 deep. All rifling has a certain amount of angle to the sides of the lands as a natural effect of the rifling process. December 5, 2013, 04:21 PM #16: WESHOOT2. 6. Krieger single, point, cut-rifled barrels have set numerous. . ”. If the barrel chamber finish reamed to the desired headspace still causes the issue, then a leade reamer is needed. Origin action hawk hill 6. Are you meaning to say that they use a button to form their rifling? Because a button doesnt cut and your claim they they use a button to cut is objectively incorrect. Single-point cut rifling, also sometimes called hook rifling, is not the most economical method, as it is very slow. Respectfully, I feel confident in saying a $50 Green mountain blank will be far. A newer method of rifling barrels, called Electrochemical Rifling, does not involve the normal machining processes of the other techniques. Button-swaged rifling. Cut Rifling – This is an older, more traditional method that isn’t commonly used today. The twist is exact, where as other forms of rifling can have variances due to the process they use. The main difference between button rifling and broaching is that broaching cut metal; button rifling simply pushes the metal out of the way. The helical groves cause the bullet to spin when fired, stabilizing the trajectory and improving accuracy. 5R is a 5-groove rifling pattern with sloped or angled sides to the lands. Images of Cut-Rifling process courtesy Accurate Shooter Rifling is usually expressed as a twist rate; that is the length required to complete a full revolution along the horizontal access. The broach is fed down the barrel with a rotation that matches the twisting ground in the tool, with each progressive tooth increasing the depth of the cut. It is chambered in 30 BR and it is accurate. #3. Today, four- and six-groove barrels are the most popular. Verified answer. Following that you can see barrels being contoured, polished, and inspected (with air gauge and bore-scope). Fig. It uses a long tool with multiple teeth. Push the the first patch all the way through the bore and out the muzzle. This comment assumes this rig is a cut rifling machine. If I was forced to pick a winner it would be the Remington. This sort of cutter design was used by gunsmiths for a very long time, all the way to about World War II. Marlin appears a bit better designed - any thoughts pro / con ?The rifling head is a hollow cylinder, and is made of high-carbon steel with a slot for the cutter cut lengthwise, about two inches long, on one side. This article describes in detail how barrels are crafted, using both cut-rifling and button-rifling methods. Gun barrels are the most critical part of a quality firearm, and our products are hand-made by craftsmen experienced in both machine tooling and competitive shooting. The discs are produced by milling away parts of a larger diameter stock piece, leaving the discs standing upright on the support rod. And my thought is that square edge of the lands being sharp wear faster. Drill and reamer marks are not removed by button rifling as they are with cut. "The most important part of such a gun - the rifling in the barrel - is in the Ballard the best yet produced. 0001 inch, or 1 ten-thousandth of an inch, at each pass, thus taking several hundred passes. Button rifling causes the metal in the bore to displace around the die and is. ” Like leather seats in a fine automobile, cut rifling pairs with upscale custom rifles. They use a wooden rifling bench,with about a 3" diameter maple cylinder with the rifling grooves cut into it with hand tools. This process is no longer common. Marlin started using Microgroove rifling in the early 50's and before that they used Ballard rifling. The cutter is a single tooth cutter that is adjusted for height by packing a thin piece of paper under the cutter,sandwiched between the cutting head and a half round slip of hard wood. 003″ – . Then he’d. All the new barrels are 1in 18", some say a fast twist for this rifle. For. Each is interesting in its own way. These days, specialized equipment is used to insert a cutter in the drilled-and-reamed bore of the billet in order to cut and remove a small amount of steel with each pass of the cutter. It has been circulated around the shooting community for years that MG barrels don't do well with cast bullets and it a commonly held belief. Button or cut rifling leaves a linear pattern. There. "Round bottom CUT rifling . We proudly create rifle barrels for F-Class competitors,. Single-point rifling. Legit print (The Springfield 1903 Rifles by Brophy, pg. Cutter is made to SAAMI specs. 0)Actually, making the rifling in a gun barrel can be done in a few ways. The bullet was quite tight and twisted as it came out. 4 groove barrel rifleing Do a search on the hide about cleaning 5R rifling etc. at the center of the slot I drill through to the shoe recess, 0. A straight and level reamed bore is the foundation for any precise rifling to be cut. Some folks think cut rifling can wear quicker due to the sharp interior surfaces. It was a success. Then the rerifling process involves the rifling cutter moving in and out of the barrel approximately 300 times (50 times per groove). This required multiple iterative passes of a cutting head for each groove (at first this was done with a "scrape cutter", and later a "hook cutter"). Building on a savage action, have an additional post in competition forum but figured I'd ask the barrel question here Guess wondering the accuracy difference one could expect out. This spin keeps the bullet travelling in a point-first direction and lessens any tendency for it to. A spinning bullet is found to be more stable in its trajectory, and is therefore more accurate than a bullet that doesn’t spin. It is possible to make a rifling machine to do cut rifling out of a lathe, but it is no longer a lathe after the required modifications. The answer was the broach. #1 · Feb 8, 2018. The first rifling method to date, which is now done with modern machinery. Shape, number, and depth of grooves can be changed easily. This plug should never be removed from the bore until its work is finished. We want a snu 2 fit. The lower is the 1. Cut rifling is the oldest method of rifling a gun barrel. Scrape Cutter. Wasn't caught during final inspection or was ignored. Cut rifling is the oldest method of rifling a gun barrel. Gun-maker Bear Creek Arsenal has a good article on its website about rifling barrels. Now them making 20mm, 25, 30 and up to 105mm they can do and if I recall correctly they do a form of cut rifling but they just cannot do small caliber stuff. Cut rifling - Cut rifling creates spiral grooves in the barrel by removing steel using some form of cutter. Grooves in the Old Days were anywhere from . with the catch being that we were always talking about cut-rifling. SPECS: 22 call land/groove diameter: . * Cut-rifled barrels are drilled, then reamed to bore diameter. Traditional (Lands-and-Grooves) Rifling Standard rifling in pistols, which seems like an after-thought to most people, is called Lands-and-Grooves rifling. Their single-point cut-rifling process delivers the most consistent and accurate results. The section on hammer forging is written by Ruger’s head of barrel making, Vern Briggs, and James Higley, Professor of Mechanical Engineering Technology at Purdue University Calumet in. In this video, Jim goes behind the scenes and shows the process he developed for rifling our 44" muzzleloader barrels. Conversely, the scrape cutter has mu l ti-point cutters inset into the opposed sides that can scraped a minimal of two opposed grooves to all grooves at a time. The carbide button tool is attached to a rod of high tensile steel, and the other end of the long rod is attached to a. I hope the pics make the operation more comprehendable. Broached rifling. Bullets fired down rifled bores must be slightly larger than bore diameter so they can be gripped or “engraved” by the rifling. Button rifling can produce a very smooth interior finish, and the majority of winning 6PPC barrels are buttoned. Lilja prefers to button rifle his barrels. 1 x 0. Done well, button rifling probably makes the next smoothest barrels. 001" thick chip by hand. 1 diameter. It is essentially a negative image of the barrel, i. The cutter was a series of 4 or 5 "teeth" filed at about 30 degrees to the axis of the shaft. Join Date: February 20, 1999. DeHoff gun barrel machines are used by over 50 firearms companies all over the world. Our President (my father), Steve Dahlke, partnered with John Krieger to establish a button rifling process capable of match grade performance. I believe they called it electrolytic rifling. Using a small 1/8" chisel, carefully remove the wood from the inside the mortise to a depth of about 1/32" to 1/16". We. Button-swaged rifling. A sine-bar scrape- or hook-rifling setup is far more suited to one-offs. Rifling Twist:. It’s also the most accurate. Lots of fine grooves, but nothing on the barrel about "micro groove" rifling, it has an 8 digit serial, 21XXXXXX. 004 deep per side per groove. The discs are. Osprey Barrel Works is a premier brand, 416RR CReS precision rifle blank. The cutter is shaped like a wide and squat "t" to fit into the slot with the center vertical of the "t" passing through the hole. The most common cut rifling method used in. I am looking to build up a lever . Remove the cutter and using the knife, slightly deepen the lines. In a 50 caliber rifle, the cutter is ground to an exact radius to create a round shape that is a circle. The 80DL was made from 1941-1964 and the 80C was made from 1941-1971. All of our barrels are manufactured using single-point cut-rifling and each and every barrel we make is thoroughly inspected and held to the same premium match grade standards, whether its an ammunition test barrel, a custom bolt action barrel or a ready-to-install finish chambered. This is the rifling bench from Dixon's 2008. Multiple cutting surfaces to distribute stresses are arrayed on a long steel rod. On the phone he said I had a good reputation locally for turning out nice machine work and asked me if I wanted to learn the art of drilling, reaming, cut-rifling, & lapping barrels. Then the bar is placed in the drilling machine. if you're talking about seating conicals, you need to be using shallow groove rifling. Cut rifling is single point broach rifling, you are. Ballard rifling was 'cut' using a cutter, or cutters, turned in a previously prepared barrel blank at the preset twist rate. Courtesy of FirearmsID. Gauging Equipment. Images of Cut-Rifling process courtesy Accurate Shooter Rifling is usually expressed as a twist rate; that is the length required to complete a full revolution along the horizontal access. It would be a lot more durable. 22 caliber barrels or pellet guns. a quality barrel will shoot good no matter which method used to rifle it. In order to produce rifling similar. Cut Rifling Cut rifling is the oldest method of rifling a gun barrel. Broach rifling is a cutting process that uses a long, multi-toothed tool that gradually removes small amounts of material from each groove. Two. Shows in detail how to build and operate both the scrape cutter and the hook cutter. Much faster is the tungsten-carbide button. Brady said: “Bartlein Barrels was started in 2005 by Tracy Bartlein. The collar has a screw that is turned to lock into the holes. groove deeper on one side than the other, thus giving the illusion of "ratchet" rifling. Once the rifling has been cut the barrel goes through its final stress relieving process, done in PPB’s “oven” at varying temperatures up to 1050℉. Our barrels come in two forms: cut rifled and button rifled. Cut rifling is no longer considered economical in mass prod. We thought of something like John Browning’s hardwood rifling machine, updated, but it seems wiser to first undertake a survey of available and historic technologies. This is because the cutter is not supported on both sides of the cutter box. Cut rifled tubes can be made a few Rc points harder which should help in longevity. 4 According to the American Precision Museum, who currently displays the Robbins & Lawrence. 308") so it would seem that it wouldn't take too much to make rifling but it is kinda important that it is twisted just right, that is the difficult part. J. (see my homepage) Also see page 204 in the 1968 Gun Digest. Then the rifling was cut. 32 and . PC barrels are now button rifled and made by T/C. #14 · Aug 14, 2021. Are you meaning to say that they use a button to form their rifling? Because a button doesnt cut and your claim they they use a button to cut is objectively incorrect. This video shows the process of cut-rifled barrel-making by one of the world's best barrel manufacturers. A 3-inch barrel with 1:14” twist spins its bullets the same as. For a 1911, the firring, external barrel dimensions and the heat treat of the barrel are likely more important than the bore quality in the long run. None of which can be done on a standard lathe. Brux Barrels is a machine tool company located in Lodi, Wisconsin, specializing in the finest custom-made cut-rifled barrels. Stress Relieve Oven with automated loading system. Double scrap cutter tooling was being used/made back even when the cut rifling was done manually by a human pulling the cutter thru the barrel by hand! Places have converted/modified the Pratt’s for pulling broaches and even pulling buttons. Occasionally during this process something goes wrong. Conventional rifling, while effective, can be improved upon in two ways. Krieger cut-rifled barrels have set numerous world records and are favored by many top shooters. Button barrels the twist is mostly controlled by the shape of the button and the twist rate can vary depending on many variables. When the gun is discharged, these grooves cause the bullet to spin as it travels the length of the barrel and thus stabilize the bullet during flight. Place the rifling cutter into the barrel of the gun and begin to make the cuts. In 1953 Marlin Firearms was issued U. Why because they don’t understand the tooling for cut rifling is one. The rifling process is a key part of barrel manufacturing, resulting in lands (bore) and grooves that create a spiral down the length of the barrel. 010 deep. 45 to . This process is done after there's a hole in the barrel blank. You may need to adjust the speed of the cutter as you make the cuts. Hi all, yep I`m making a sharps rifle on my lathe, what is the best rifling twist for the 45-70 cartridge with black powder, I can get 1 in 24" and a max barrel length of 25". Twist. Even if scrape cutter rifling requires less time to produce grooves, both processes are time-consuming and incompatible with large-scale manufacture since the cutter may require several sharpening or even replacement (Biasotti, 1981; Bonfanti, 1997). A: Rifling formed by cutting away metal from the bore usually has fewer lands and grooves than “button rifling” formed by forcing a tungsten carbide die through the bore. This sets us separate from the other barrel maker's out there that drill with a stationary drill with the barrel rotating. 4. Now, fold or cut the patch for a snug, not tight, fit. It takes far longer to cut-rifle than to button- or broach-rifle a barrel. With a gain twist barrel the bullet cannot go to sleep. Broached rifling. See Krieger Barrels being made, start to finish. The machinery to cut the rifling is very simple. It is mostly all automatic with a long shaft with a ground cutter made from TanTung or Cobalt. Tooling – gundrills, reamers, rifle buttons. Also when a rifling head is used in scrape or hooked rifling the groove depth will be shallow when the head is introduced into the bore and again when it is removed at the muzzle end. There are two main rifling types, standard and polygonal. 150-gr. This is one of the oldest methods of rifling and dates back to the time that rifling was first invented in Nuremberg, Germany in 1520. Square bottom CUT rifling to . 010. Lawton did cut rifling, and also produced the worst barrel regardless of rifling method my gunsmith ever had in his shop with 33 years gunsmithing experience. impressed into the metal as the negatives of minute imperfections found on the rifling cutter’s surface ; these markings will be unique to each gun made - thus the marking will be individualizing characteristics to a single gun. The six groove deep rifling was designed to spin the soft lead shells that were generally being shot at the time. The result is a clean, 3-degree pocket hole with minimal tear-out, around either the pocket or the pilot hole. I agree with you that "Pac-Nor does in fact use a button" but they are not cut (I just called and asked this specifically). On my 3 groove barrel you can clearly see the leading edges of the lands being eaten away at. Polygonal barrels have gently rounded polygonal pattern, usually a hexagon or octagon. Not sure about the cut or button detail. Unlike the above-mentioned barrel makers who usually specialize in one rifling method (either button or single cut rifling), Rock Creek offers either rifling solution. Electron discharge machining (EDM) The following types of rifling use similar processes as the ones aforementioned. JES Reboring converted a Remington 760 slide action from -30-06 Whelen to 35 Whelen Whelen. Cut rifled at this point in time is a rather expensive specialty product for high end precision barrels. Cut rifled at this point in time is a rather expensive specialty product for high end precision barrels. The Model 444 was introduced with a 12. 6), and 140 eld-m average is 2715 Nearly a grain more in powder but 55fps slower. In a 50 caliber rifle, the cutter is ground to an exact radius to create a round shape that is a circle. The barrel has a 5GR cut rifling with a 1-8" barrel twist. Gun barrel markings. Many of the largest and most respected names in the firearms industry rely on us for our outstanding commitment to quality and on-time delivery for their firearm related tooling. The cutter rests in the cutter box, a hardened steel cylinder made so it will just fit. Current is applied and the “wet etching” process eats away metal in the desired areas to produced. 308-inch bullets instead of . The only exception to this rule is Forsyth style rifling with wide grooves, and narrow lands. I cut the shoe recess, 1-3/8 inch long about 1/2 way through the rod. Conventional rifling has sharp 90-degree corners from the top of the land to the bottom of the groove. You will even find some loading books that say, cast bullets don't do well in MG barrels past about 1. The scrape method was used for round ball barrels since they needed deeper grooves when. Since the rifling is cut by a broach, you need a different broach for different rifling twist rates. Cut rifling is done by hand or with a tool that cuts one groove at a time through the barrel. It was a tedious and expensive process in which each groove was cut by hand. The 27. Whether it’s button rifling (100-400 Series), broach rifling, cold hammer forging, or single-point cut rifling (500 Series), there are plenty of valid options to choose from. Fairly sharp , (but not too sharp as to cut the patches) lands grip the best. Texas. RIFLING CUTTER (SCRAPE TYPE) TO DEEPEN EXISTING GROOVES IN BARREL USING EXISTING RIFLING IS GUIDE. He used stress-relieved steel for all his barrels. 224. GMX bullets shows rifling lands road over the top of the. What im saying is from what Ive seen from two different barrels with diferent styles of rifling. Bear Creek Arsenal. 1. Normally expressed as the peak pressure in pounds per square inchWe rifle by the single-point cut-rifling process. What im saying is from what Ive seen from two different barrels with diferent styles of rifling. Sizes range from 14 caliber Rifles to 10 gauge rifled shotgun barrels and can be ground with any helical twist right or left handed. Cut rifling appeared in Nuremburg in the late 15th century. The result was a bore that looked like the patched ball was sliding on thin rails. This required multiple iterative passes of a cutting head for each groove (at first this was done with a "scrape cutter", and later a "hook. This type of rifling is produced with Hammer Forging . Hold the equipment square, parallel, and concentric everywhere, because precision is the byword in barrel making work. Krieger barrels are single-point cut-rifled, and hand lapped after reaming and after rifling, which is the most time-consuming method for rifling a barrel. The Model 80 and 80E were made from 1935-1939 while the 80B and 80BE were made in 1940 only. This is what I got from my S&W engineer acquaintance this evening. The Broughton 5c rifling looks alot like the rifling in a glock no sharp edges. The first thing I did when I took the rifle out of the box was to weigh it and it was just barely over six pounds. The main focus of the article is on Cold Hammer Forging of. As the barrel is cold hammer-forged, a giant machine literally pounds the barrel from all sides around an internal carbide mandrel, which forms the rifling inside the bore. , a receiver only. Next comes the big stuff — the massive rifling machines that single-point-cut the rifling in a precise, time-consuming process. The rifling cutter should cut the groove into the barrel of the gun at a slow, steady pace. They are owned and operated by shooters who have been involved in barrel making for many years. Cut and button rifled processes can be altered to accommodate varied twist rates, other than in extremes, whereas cold-hammer forging needs the mandrel within to be the exact shape of the bore, including the twist rate. Polygonal rifling is common in pistol barrels, and is used by Glock (Gen 1-4), Walther, Heckler & Koch, and several other companies. . pulled button also continues. The rifle is also available with an optional 20″ or 18″ barrel length as well as a muzzle brake if you so desire, but the recoil of this rifle is easily manageable. I think one "con" is that the "5R" name is getting a bad rap due to recent marketing. 5R is an improvement over conventional rifling by changing the shape and configuration of the lands and grooves. While button or cut rifling must start with a hole somewhat smaller than finished size, hammer forged blanks have holes about 20% larger than finished size. Forged rifling. $189. Button rifling, where a mandrel with the rifling pattern is pushed through the barrel, is commonly used in rimfire barrels. In addition, the article describes a new (and somewhat radical) method, Cation Rifling, which employs acid to etch. LaBounty worked out a method for his rifling cutter to follow the old rifling, deepening it slightly. The curved surface of the cutter holder opposite the working edge bears against the side of the barrel for support and alignment. A broach can be used to cut rifling into the inner surface of a barrel, b. The sides of the grooves are parallel, but the sides of the lands are not and the 5R carries this to an extreme. One was hammer forged and I haven't seen a smoother bore on a rifle out of the box. depth of . 0001” deviation between each other because they. Polygonal rifling . The rifling cutter should cut the groove into the barrel of the gun at a slow, steady pace. Button Rifling. Twist rate is also spot-on, on cut rifled tubes. The last place you want it to go sour is right at the muzzle. 2. The first barrel was converted to a 35 caliber barrel, and then a variety of other calibers were. The top shooters in Benchrest are the ones who can really 'see' the minute differences in barrel accuracy. You impart a smooth surface finish, its cost effective, and the bad news of button rifling (setting up additional stresses in the barrel) is not. 300-inch bullets, . This process is repeated until the grooves reach the desired depth. All blanks available are in stock and contoured to order. The cutter removes approximately . The cutting tool used is called a "hook cutter". 016 deep. The cutter is pulled through again and again, deepening slightly between passes until the groove is the desired depth. Polygonal rifling does not cut grooves. Rifling tool having one or two raised cutting edges that cut the grooves of rifling. Cut rifling creates spiral grooves in the barrel by removing steel using some form of cutter. Here's a breakdown of the 3 main types of rifling, Cut rifling, button rifling, and cold hammer forged, and what we believe are the benefits. Cut rifling can produce rifling as good as any method. Now, many years later, I find that rifling that is too deep can be more of a hinderance, than a help. The cutter removes approximately . Fifty. !f you look what is used. 012 deep. If the chip is not the full width of the groove, it means there is a nick in the cutting edge, or your cut is not deep enough. usually much shallower than conventional cut rifling. They are available in rifle only, bore only, or combination style. Our barrels are gundrilled with counter rotating gundrilling system. I do know that almost all precision rifles use cut rifling (with the exception of the HK PSG-1 and a few other examples), however, so there must be something to the theory. This gives the polygonal barrels a tighter gas seal on the projectile. 13). Gauging Equipment. This may be changing with the advent of contoured (5R) cut riflings. Cut rifling is more precise and makes a difference for those. Yes, each is a different method of rifling, but Microgroove rifling generally consists of 12 lands and grooves, vs 4-6 lands and grooves for other methods of rifling a bore including Ballard rifling. 22 caliber barrels or pellet guns. Which is why we’ve made it our mission to provide a hassle-free foam recycling service for our. A round bottom groove design is very good for PRB's, with deeper grooves. About 1550, Gaspard Zeller or Zollner, of Nuremberg, Germany, cut spiral grooves in the barrels of guns; but rifling in its perfected state is almost entirely an American development, a highly important step in the generation of the rifle which was designed. 5R – A 5-groove rifling pattern that is sloped or angled side to the “lands. However, this situation will change as many firearms now being made are being rifled by newer methods which have the advantage of being. It can also produce superior barrels, thanks to. . They also have a great rifling machine and have developed a great scrape cutter to use with it. With cut rifling, grooves are carved into the barrel using a cutting tool, whereas with button rifling, grooves are pressed into the metal using a hardened steel button. 001) per pass, so it is by and far the slowest (but most accurate) form of rifling. Square bottom CUT rifling to . Criterion began in 1999 with a single OEM client in need of a economical, high volume option to cut rifled barrels. The grooves are usually parallel in barrels while the sides of the lands are not. The GROOVES are a bigger diameter than The Caliber or Bore. Cut-Rifling: This is the oldest and most accurate method of rifling. Grab a cleaning rod, jag and patch. 002-0. How many grooves does a scrape cutter make with one swipe? 2. Cut rifling is the oldest method of rifling a gun barrel. Rifling consists of these grooves and the metal left between the grooves—the lands (see Figure 1. It stands apart from most modern barrels’ six lands configuration. It is all open oiling with many oil pots. Before 1950 all Marlin barrels were made by drilling the bore, and then cutting the rifling one groove at a time on a sine-bar machine. Cut Rifling Machines. Also I do believe in the 5R rifling does help fight bullet failure. This required multiple iterative passes of a cutting head for each groove (at first this was done with a "scrape cutter", and later a "hook cutter"). Then, grooves are cut, leaving the original hole's surface as. engineering. Parallel spiral grooves cut or impressed into the bore of rifles and pistols in order to make them spin, insuring a steady, point on flight to the target. 308. Rifling begins by mounting the barrel in the machine and setting the desired direction and rate of twist. For large caliber solutions we use UNISIG B-Series deep hole drilling machines for drilling and bore finishing and a R100 or R200 CNC rifling machine. 0001 inch on each pass, thus taking several hundred passes to rifle a barrel. Cut rifling, including single-point hook and scrape cutters, the saw cutter and broaches are covered. Rifling consists of spiral grooves cut into the inside of a barrel of a gun. Don't know about Chanlyn's backlog. . The cutter is adjusted to cut one- to two-thousandths of an inch of metal on each pass. Equipping the barrel with the spiral grooves that spin-stabilize a bullet is the essential operation that defines an entire category of firearms. It performed as such in the field, changing POI 1 1/4 MOA vertical and 1/2 MOA vertical between cold and 4 shots warming, consistently moving the POI low and left over the 4 shots.