Choke shotgun markings

ATA shotguns typically use interchangeable chokes with varying degrees of constriction to effectively control the spread of the shot pattern. These chokes include but are not limited to full, improved modified, modified, improved cylinder, and cylinder. Contents [ …

Choke shotgun markings. Huglu fixed choke markings. Looking at an older fixed choke TR Import gun for my wife at a local shop. Choke markings are 1 circle and 2 circles. Just wondering what they constriction that relates too? Wish I could help you, you will have to wait for 2few, or Riflemeister to help you out.

A shotgun barrel’s choke will be located at the muzzle end of the barrel and you will encounter them in two different designs. The oldest way is called a “fixed choke.”. Many side-by-side and older single barrels will have fixed chokes, meaning that their barrels have the choke constriction built-in to the end of the barrel at the muzzle end.

As a general guide:-. 1 star or notch is Full choke. 2 stars or notches is Improved Modified or 3/4 choke. 3 stars or notches is Modified or 1/2 choke. 4 stars or notches is Improved Cylinder or 1/4 choke. 5 stars or notches is Cylinder or no choke, this tube may also have no markings at all. This all pales into insignificance when you look to ... S. soreshoulder. 328 posts · Joined 2003. #2 · Nov 11, 2003. My Fox Model B had neither choke markings or a serial number, for that matter. Your gun is probably choked Modified-Full, although it could be Improved Cylinder-Modified. Take it to a smith...he'll have the gauges to make the determination.14040 posts · Joined 2009. #3 · Feb 22, 2010. When I figured out the markings, I wrapped the end of each extended tape with masking tape and wrote on the tape with a magic marker the choke size. Works for me, and I don't have to wear my reading glasses in the field. "We pulled the trigger, the safety went forward, both barrels fired almost ...A5 guy. Thanks for the confirmation on the chokes and the judgement on the Grade (>>Looks like a Diamond Grade. Nice gun!<<) When my uncle bought this gun almost 40 years ago at the Okinawa PX, he also bought a Browning Auto 5 at the same time. Small coincidence. Anyone else want to weigh in and confirm or deny the Diamond …The tighter the choke the heavier the radial forces, the tighter the pellets are squeezed together so the pattern holds tighter over a longer distance. Conversely, the less restriction you have in the shotgun choke the more loosely the pellets are held together and the faster the pattern opens up. There you have it!Definition of Chokes. A choke is a tapered constriction of a shotgun’s barrel bore at the muzzle end. Chokes are used to shape the spread of the shot in order to gain better range and accuracy. They come in different types, each designed for a specific purpose in shooting. Definition of Skeet Shooting.A choke is a valve installed in a carburetor that restricts air flow, which enriches the fuel-air mixture when an engine is started. According to Autorized.com, a choke is designed...

How to identify the right Choke Tube for your gun: Identification Methods. 1) Visual Method. 2) Choke Measurement Method. 3) Barrel Markings Method. 4) Serial Number Method. Choke Tube Constrictions chart. How can I identify which screw in choke tubes I should use in my Beretta shotgun: Mobilechoke, Optima-Choke, Optima-Choke Plus, or Optima ...Hello, i came to this forum to get some help determining the type of chokes on my shotgun, its a Acciao Breda B4 oxu, old shotgun, the markings on my Left (upper) barrel is 18.4 and on the Right (lower) is 18.3, im pretty lost on how to calculate the choke type, if anyone could help me know more about my shotgun not only choke type if full, improved cylinder, modified, etc.Gunsmithing. Briley Showroom. Mattarelli USA. Briley 3Gun. Premium European to American Markings Choke Charts which are manufactured to be the best in market with the highest quality shotgun, firearm, and rifle standards. Shop now for European to American Markings at Briley, A Legacy of Shooting Innovation. How to identify the right Choke Tube for your gun: Identification Methods. 1) Visual Method. 2) Choke Measurement Method. 3) Barrel Markings Method. 4) Serial Number Method. Choke Tube Constrictions chart. How can I identify which screw in choke tubes I should use in my Beretta shotgun: Mobilechoke, Optima-Choke, Optima-Choke Plus, or Optima ... 2454 posts · Joined 2006. #3 · Dec 6, 2007. The Franchi is an European made shotgun.Most European shotguns are marked with stars on the barrel as to the choke rather than being marked with the the words. On the barrel of the shotgun there should be a series of stars.One star /full,two stars improved modified,three …I can find no other markings on the gun other than a "G" and "35" stamped on the bottom of the barrel where it is covered by the receiver when the gun is assembled, and also a "G" and "35" stamped on the inside of the receiver where it is covered by the barrel when the gun is assembled. There is no other serial number or choke marking on the gun.

Aug 30, 2008 ... Choke, Notches. Cylinder, /////. Skeet, /////. Improved Cylinder, ////. Modified, ///. Improved Modified, //. Full, /. Then there's the ...The three major parts of a shotgun are the stock, action and barrel. Other parts that may be found on a shotgun include the trigger guard, safety mechanism, magazine, sight and for...6240 posts · Joined 2007. #4 · Feb 11, 2010. Measuring is an indication. The only real way to know what the choke is is to shoot patterns at 40 yards, draw a 30-inch circle around the most hits and start counting. By definition choke is the percent of the charge in a 30-inch circle at 40 yards. Like.145.1Kmembers. Since 2000. A forum community dedicated to Shotgun owners and enthusiasts including the Remington, Beretta, and Mossberg shotguns brands. Come join the discussion about optics, hunting, gunsmithing, styles, reviews, accessories, classifieds, and more! Show Less. Full Forum Listing.Sep 21, 2020 · Hello, i came to this forum to get some help determining the type of chokes on my shotgun, its a Acciao Breda B4 oxu, old shotgun, the markings on my Left (upper) barrel is 18.4 and on the Right (lower) is 18.3, im pretty lost on how to calculate the choke type, if anyone could help me know more about my shotgun not only choke type if full, improved cylinder, modified, etc.

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1) Visual Method. 2) Choke Measurement Method. 3) Barrel Markings Method. 4) Serial Number Method. Choke Tube Constrictions chart. How can I identify which screw in choke tubes I should use in my Beretta shotgun: Mobilechoke, Optima-Choke, Optima-Choke Plus, or Optima-Choke HP?In today’s fast-paced digital world, live streaming has become a popular and effective way for individuals and businesses to connect with their audience in real-time. One such live...Jan 17, 2021 ... Choke Tube Install and removal explained as well as purposes for different chokes.6534 posts · Joined 2013. #9 · Jan 5, 2021. And just to note, before someone states the above specs are SAAMI and "do not apply" to a gun manufactured in either Belgium or Japan, where CIP reigns, the CIP specs for a 12-gauge barrel are 18.2mm+0.7mm, so 18.2-18.9mm. Which, math says are 0.71653" to 0.7440944".Choke Notches and Their Meanings. The notches on a shotgun choke are there to indicate the constriction level and the resulting pattern it produces. Each notch represents a specific choke setting, allowing you to determine the amount of spread your shot will have.Shotgun choke markings can be identified using 5 simple methods. They include referencing a sizing chart to find the correct choke, counting the lines or notches, observing dots or circles on the choke, locating writing on the side wall, and using bore …

A “Cylinder Choke” will provide the best accuracy. Any choke with constriction of .020″ or more can result in damage to the barrel. Our “Improved Choke” tubes have a constriction of .013″ and therefore may be used with rifled slugs; however, accuracy may be compromised. Weatherby recommends slugs only be fired using a non-ported ...Aug 7, 2008 · The chokes in an L.C. Smith run parrallel for 1" and then taper 1 9/16" to bore size of .729-.732 in 12 ga. Also your gun was made in 1908, and after 1913 the 0 grade became Ideal Grade. The markings on the barrels are probably the barrel makers mark as the 0 grade had London Steel barrels or Damascus steel, I think Chain Damascus. Optima-Choke choke tubes will be marked Optima-Choke. The start of the threaded portion of the Optima-Choke tube is located a nominal 50.78 mm (2.00 inch) from the breech end of the choke tube. The length of the threaded portion is a nominal 15.9 mm (.625 inch). The major diameter of the choke tube thread is 20 mm (.787 inch).S. soreshoulder. 328 posts · Joined 2003. #2 · Nov 11, 2003. My Fox Model B had neither choke markings or a serial number, for that matter. Your gun is probably choked Modified-Full, although it could be Improved Cylinder-Modified. Take it to a smith...he'll have the gauges to make the determination.If a shotgun has an improved-cylinder choke, the constriction in the barrel is 0.010 inches. If a modified choke, 0.020 inches. If an improved-modified choke, 0.030 inches. A full choke, 0.040 inches. Full choke will place 70 percent of the pellets from a shotshell inside a 30-inch circle at 40 yards. However, increasing the barrel constriction ...As a general guide:-. 1 star or notch is Full choke. 2 stars or notches is Improved Modified or 3/4 choke. 3 stars or notches is Modified or 1/2 choke. 4 stars or notches is Improved Cylinder or 1/4 choke. 5 stars or notches is Cylinder or no choke, this tube may also have no markings at all. This all pales into insignificance when you look to ...Most double shotguns represented here. Double gun shotguns - Side by Side shotguns, and over under shotguns - Including drillings, double barreled rifles, SxS double rifles, combination guns. Makers - Darne, Merkel, Arrieta, Beretta, Browning, Holland, Purdey, Richards, Bernardelli, Parker, Fox, LC Smith, and most other double barreled shotgun, …Most double shotguns represented here. Double gun shotguns - Side by Side shotguns, and over under shotguns - Including drillings, double barreled rifles, SxS double rifles, combination guns. Makers - Darne, Merkel, Arrieta, Beretta, Browning, Holland, Purdey, Richards, Bernardelli, Parker, Fox, LC Smith, and most other double barreled shotgun, …

S. soreshoulder. 328 posts · Joined 2003. #2 · Nov 11, 2003. My Fox Model B had neither choke markings or a serial number, for that matter. Your gun is probably choked Modified-Full, although it could be Improved Cylinder-Modified. Take it to a smith...he'll have the gauges to make the determination.

Barrel Markings Method. Serial Number Method. Choke Tube Constrictions chart. How can I identify which screw in choke tubes I should use in my Beretta shotgun: Mobilechoke, Optima-Choke, Optima-Choke Plus, or Optima-Choke HP? Here we present different methods by which you can identify the right choke for your shotgun.The choke tube table above shows the diameters and constrictionsyou can expect for choke tubes and shotgun barrels for SKB 12-gaugeshotguns compared to common fixed choke shotgun gauges. Knowing the diameter of a choke tube is important in order to identify choketube constriction. The tighter the choke tube, the more constriction it has and the ...Sep 14, 2023 ... | How to Shotgun: There's no question that when it comes to choke tubes, there are A LOT of options. Even if you're using the factory chokes ...The choke tube table above shows the diameters and constrictions you can expect for choke tubes and shotgun barrels for Benelli 12-gauge and 20-gauge shotguns featuring the Crio, Crio Plus, and Mobil choke systems.Knowing the diameter of a choke tube is important in order to identify choke tube constriction. The tighter the choke tube, …1. Visual Method. The fastest way to identify the “Family” is to take down one choke you are currently using on your shotgun, clean it and cheek the markings on the side of the choke, here an example: In the example image, you see an Optima-Choke HP Choke. Note: Mobile-Choke “Family” could also be marked as “PB” or “ST”. These choke diagrams compare similar choke systems for different brands and highlight key features in order to identify which choke you have. Choke design, thread location, thread count, and other key identifying features are all listed to make for rapid identification. Standard Invector vs Invector Plus. Invector Plus vs Invector DS. S. soreshoulder. 328 posts · Joined 2003. #2 · Nov 11, 2003. My Fox Model B had neither choke markings or a serial number, for that matter. Your gun is probably choked Modified-Full, although it could be Improved Cylinder-Modified. Take it to a smith...he'll have the gauges to make the determination.Deciphering Auto 5 metric choke markings. I recently acquired a 16 ga. pre-War Auto 5 with a serial number in the 51,000 range. It does not appear to have the asterisk-style choke markings, but on the underside of the barrel it is marked as shown. I am assuming that this might represent a choke with a 0.1 mm constriction (16.9/17.0 mm).

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CZ 1012 G3 12 gauge: interchanges with Trulock’s CZ II style. (Flush choke length 2.750 in.) CZ 620 20 gauge: interchanges with Trulock’s Benelli Mobil style. CZ 628 28 gauge: interchanges with Trulock’s Beretta Mobil style. CZ Bob White: interchanges with Trulock’s Beretta/Benelli Mobil style.Choke Notches and Their Meanings. The notches on a shotgun choke are there to indicate the constriction level and the resulting pattern it produces. Each notch represents a specific choke setting, allowing you to determine the amount of spread your shot will have.According to the patent, WS1 is a constriction, maximal about 1" from the muzzle, followed by a flare. When people measure WS1s they often come to the erroneous conclusion it is a "negative" choke. And even large auction houses forget to include a measurement of the constriction area. The constriction varies according to gauge.Choke Type: Identification (Notches, Stars, Alpha Code, or Color Band) Extra Full: No notches, no stars, XFULL Turkey, no color band: Full Choke:choke identification? Jump to Latest Follow ... A forum community dedicated to Shotgun owners and enthusiasts including the Remington, Beretta, and Mossberg shotguns brands. Come join the discussion about optics, hunting, gunsmithing, styles, reviews, accessories, classifieds, and more! ...1108 posts · Joined 2005. #11 · Jul 4, 2007. Fastarget is correct. Merkel chokes tend to run tight. My 1620 is marked VBZ/1/2 (IC/Mod), but the chokes patterned more like Mod/Improved Mod. I opened the IC barrel to skeet and the left barrel remains a tight Mod. It makes for a pretty versatile gun.It is a 20 gauge with 3-inch chambers. The choke markings appear to be 14.9 stuck over 15.5 on the right and 14.6 struck over 15.5 on the left. Anyone know what this means in terms of IC< Mod, etc? ... and Mossberg shotguns brands. Come join the discussion about optics, hunting, gunsmithing, styles, reviews, accessories, classifieds, …Frank Lopez. 4626 posts · Joined 2005. #2 · Aug 16, 2006. Dan, The markings have nothing to do with choke. The 76 indicates that you have 3 inch chambers (76mm). The 18.3 is the bore diameter in millimeters or about .721 inches. Italian (and many European) bores are pretty tight, I think it has to do with the fact that they still use felt and ...May 30, 2023 · The second shotgun choke that worked really well in the field – in that it was effective and forgiving in use – was a standard Beretta Improved Cylinder Mobilchoke tube. This is a conventional shotgun choke with about five thou of constriction. With the duffer’s gun, I once accounted for 18 average pheasants for 17 shots. If you work in the field of surveying or construction, you may have come across the term “bench mark elevation correction.” This process is crucial to ensure accurate measurements ...Miroku Choke Designation. I am looking at purchasing a used Miroku 20 ga O/U with 26" bbls. It is marked *- and ** for chokes. My Browning chart says this is Improved Mod & Mod but this seems a bit odd for a 26" barreled shotgun. Did Miroku use a diffrent choke marking system? ….

I have recently obtained an older used CZ BRNO 12 gauge o/u ejector SG, MOD 501.2 manufactured around 1987-8. I’m trying to decipher the choke markings stamped on the base of the barrels. They are 17,4 ( top barrel) and 17,8 on the bottom. Could anyone please tell me how these equate to either UK choke markings, ie, Open, 1/4, 1/2, 3/4 etc.May 30, 2023. 0 shares. Shotgun choke can be a daunting subject, but can make all the difference to your shooting, so it's well worth following The Field's definitive guide. Learn exactly what shotgun choke is, what it does, how it affects your shooting and which you should be using.To do this, you need a large piece of paper or cardboard placed at 40 yards. Draw a central aiming point and shoot at it from that distance. Find the center of the pattern on the target and draw a 30 inch circle. I do this by attaching a 15” string to a sharpie and holding the other end in the center of the pattern.Many fixed choke shotguns have choke information etched or stamped onto the barrel. Look for abbreviations like “F” for full choke, “M” for modified choke, and “IC” for improved cylinder. Use a Choke Gauge. Choke gauges, readily available at most popular retailers, are simple tools designed to measure choke constrictions.If you have only one marking per barrel; it is the bore diameter. Some of those old Belgians had small bore `12 ga. 18.1 divided by 254=.712 bore size; quite a bit smaller than the standard of .729 for a 12. The English actually called those guns 11 guages. The muzzle need to be measured to get an accurate choke id.17856 posts · Joined 2003. #1 · Oct 22, 2003. Anybody familiar with the choke markings on a SIG/Rizzini fixed choke O/U shotgun. Looks like they have "0"s stamped on the side of the barrels. One has 3 and the other 4 I think it is. The guy I got it from said it was an IC and Mod. The owners manual only speaks of choke tubes, and …The markings will indicate the constriction of the tube, with different markings denoting different choke sizes. How can I tell if my Benelli choke tube is improved cylinder or modified? Look for the markings on the choke tube – “IC” stands for improved cylinder, while “M” stands for modified. Choke shotgun markings, Vintage Shotgun Choke Markings. Unlike most manufacturers, Savage chose not to mark their shotgun barrels with standard choke markings of Full, Modified, Improved Cylinder and Cylinder. Instead they chose to use a series of asterisk (*) marks as code to specify the choke constriction of a given barrel. This code can be found stamped on the ..., Jun 26, 2014 · Browning BSS 20ga chote markings. I have a 20 ga 26" tubes,fixed chokes, where are the choke markings on the barrel. I am use to the old system of stars and dashes. This is a BSS and the only thing I see under the forearm is a 3 on one barrel and a 5 on the other. Any help would be appreciated. , Mar 31, 2011 ... In that systems markings run from 4 stars for cylinder to 1 star for full. The coachgun comes with an improved cylinder, which is the 3 stars, ..., There are several ways to find out more information about your Winchester rifle or shotgun. All Winchester firearms, including commemoratives, are collectible. Read on to find out ..., 14040 posts · Joined 2009. #3 · Feb 22, 2010. When I figured out the markings, I wrapped the end of each extended tape with masking tape and wrote on the tape with a magic marker the choke size. Works for me, and I don't have to wear my reading glasses in the field. "We pulled the trigger, the safety went forward, both barrels fired almost ..., Browning choke tubes use several systems for identification. Some are useful in the field, and others when the choke tube is out. Choke tubes supplied with your Browning shotgun often have notches in the top edge which can help you determine the choke constriction., Sep 14, 2023 ... Perazzi shotgun choke markings are as follows the KG xxxx is the gram weight of the barrels the 18.4 being .724", 18.5 being .729" is the ..., The chokes had me confused with their markings. Cylinder choke says "IC on 18.6 Overbored Barrels". All chokes are marked as .010" tighter on overbored barrels. ... Rizzini made a change to newer Rizzini Plus chokes in that gun and a .735 bore. 3. Put the gun on paper and see what you have. I had one size tighter, even with Trulock., Tristar chokes can be identified by the unique markings or engravings on the choke tubes themselves, which often include the brand name or logo, as well as the constriction size or designation. Some Tristar chokes may also have color-coded bands for easy identification. See 3,000+ New Gun Deals HERE. 1. What markings should I …, When you open the gun, turn it sideways and there should be marks where the barrels go into the receiver. The marks should be something to the extent of *- or something like that. There is a thread at the top of this forum about Browning choke codes. Good luck! Open the gun and look on the left side of the Mono Block., I can find no other markings on the gun other than a "G" and "35" stamped on the bottom of the barrel where it is covered by the receiver when the gun is assembled, and also a "G" and "35" stamped on the inside of the receiver where it is covered by the barrel when the gun is assembled. There is no other serial number or choke marking on …, Shotgun Chokes Explained: How a Choke Works; Shotgun Chokes Explained: Pattern Testing; Shotgun Chokes Explained: Types of Chokes; List of Shotgun Choke Constrictions by..., Feb 17, 2024 · ATA shotguns typically use interchangeable chokes with varying degrees of constriction to effectively control the spread of the shot pattern. These chokes include but are not limited to full, improved modified, modified, improved cylinder, and cylinder. Contents [ show] , Optima-Choke choke tubes will be marked Optima-Choke. The start of the threaded portion of the Optima-Choke tube is located a nominal 50.78 mm (2.00 inch) from the breech end of the choke tube. The length of the threaded portion is a nominal 15.9 mm (.625 inch). The major diameter of the choke tube thread is 20 mm (.787 inch)., However, it’s best to pattern your shotgun with different chokes to determine which one works best for your specific hunting situation. 5. Can I shoot steel shot through my Stoeger choke tubes? ... Stoeger choke tubes often feature markings on the side or notches on the top rim that indicate the choke constriction, making it easy to …, A number of Rottweil 72's were marketed in the States by Dynamit Nobel's USA HQ in New Jersey. The Model 72 is well built and when ordered with "Tromboncino" chokes, proved deadly on Skeet. As mentioned in my earlier posts, Mr. G. Gamba currently operates a machinery distributorship on the former premises of Armi F.lli Gamba. During …, What do the markings on chokes mean? Markings on chokes indicate the level of constriction, with designations such as Cylinder, Improved Cylinder, Modified, Improved Modified, and Full. 4. What is Cylinder choke? Cylinder choke has no constriction and provides the widest shot pattern. 5. What is Modified choke?, If you have only one marking per barrel; it is the bore diameter. Some of those old Belgians had small bore `12 ga. 18.1 divided by 254=.712 bore size; quite a bit smaller than the standard of .729 for a 12. The English actually called those guns 11 guages. The muzzle need to be measured to get an accurate choke id., Choke tubes help sharpen your shotgun’s accuracy when hunting game and offer a myriad of benefits for hunters. Among the top remains the fact that chokes give you the ability to turn a single shotgun into a tool capable of specializing in many types of game hunting., Shotgun Choke Markings. A shotgun choke is found inside the bore of a shotgun barrel. It basically has a series of markings that helps shape the spread of the shot that is fired as it is coming out of the barrel. The specific choke you use determines the range and accuracy of the shot., Choke tubes help sharpen your shotgun’s accuracy when hunting game and offer a myriad of benefits for hunters. Among the top remains the fact that chokes give you the ability to turn a single shotgun into a tool capable of specializing in many types of game hunting., 2786 posts · Joined 2014. #2 · Nov 2, 2015. 2 and 4 would be modified and full. They would be the same as Ithaca guns since the Nitro Special is a Lefever in name only, Ithaca made all of them after acquiring Lefever - but I believe that you already knew that., May 6, 2012 · Shotgun Choke Markings. A shotgun choke is found inside the bore of a shotgun barrel. It basically has a series of markings that helps shape the spread of the shot that is fired as it is coming out of the barrel. The specific choke you use determines the range and accuracy of the shot. , Shotgun Chokes Explained: How a Choke Works; Shotgun Chokes Explained: Pattern Testing; Shotgun Chokes Explained: Types of Chokes; List of Shotgun Choke Constrictions by..., Frank Lopez. 4626 posts · Joined 2005. #2 · Aug 16, 2006. Dan, The markings have nothing to do with choke. The 76 indicates that you have 3 inch chambers (76mm). The 18.3 is the bore diameter in millimeters or about .721 inches. Italian (and many European) bores are pretty tight, I think it has to do with the fact that they still use felt and ..., Thanks: 3,589. Thanked 860 Times in 282 Posts. In order to accurately measure choke constriction you will need a 28 Gauge bore micrometer. With it you may find bore diameter and choke constriction which will translate into a numerical choke value by subtracting muzzle diameter from bore diameter., We would like to show you a description here but the site won’t allow us., Many fixed choke shotguns have choke information etched or stamped onto the barrel. Look for abbreviations like “F” for full choke, “M” for modified choke, and “IC” for improved cylinder. Use a Choke Gauge. Choke gauges, readily available at most popular retailers, are simple tools designed to measure choke constrictions., Image 2: This illustration shows the different types of choke configurations; jug choking is at the top. Image 3: John Robinson uses both Briley and Mirochokes in this Miroku 9000. The difference in length results in the Briley’s protruding from the muzzle. Image 4: Miroku, Browning and a number of other shotgun makers use shorter screw-in ..., What do the notches on the choke tubes mean? The notches indicate the choke tube constriction. A lower notch count means more constriction (tighter). A ..., There are a variety of choke sizes that restrict a shotgun’s bore to a greater or lesser degree. “Cylinder” chokes don’t constrict the bore diameter at all. “Full” chokes constrict the bore by about .035 inches. Between cylinder and full, “improved cylinder” chokes constrict the bore about .010 inches, “modified” constrict ..., If a shotgun has an improved-cylinder choke, the constriction in the barrel is 0.010 inches. If a modified choke, 0.020 inches. If an improved-modified choke, 0.030 inches. A full choke, 0.040 …, That is consistent with the GDR marking on the side of the barrels. 12 / 76 is the gauge and chamber length . Here a 12 gauge with 3 inch chambers. The 18.6 is the bore diameter of the barrels expressed in millimeters. 18.6 equals .732 inches or just slightly larger than the "standard" .729 bore of a 12 gauge.