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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
reamers/chambering
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<blockquote data-quote="VinceMule" data-source="post: 2853247" data-attributes="member: 122164"><p>Mike, I know you are advanced in your thinking and planning, but for those that are not, you take this drawing, make measurments on brand new brass, there is a LOT of design that still needs to be taken into account. If you have a reamer made off of exact brass dimensions, your reamer will be worthless. The print with the exact dimensions is the road map for you to now ADD clearances you want. Knowing what dimensions your dies size to is of great importance, instead of discovering a major flaw AFTER THE FACT!</p><p>You can actually make a chamber cast of the full length sizing die with Cero Safe if you are a nit pickers, nit picker.</p><p></p><p>Another issue, brass over a lot of 100 pieces may vary slightly in variations, and you need to establish a "spread" on the +/-.</p><p></p><p>Lapua</p><p>Peterson</p><p>Alpha</p><p>Winchester</p><p></p><p>have some very, very dramatic differences in dimensions, especially in the web thickness and neck thickness.</p><p></p><p>Places where many make mistakes including myself:</p><p></p><p>A. New brass dimension .200 from the bolt face, Clearance needed</p><p></p><p>B. Neck dia</p><p></p><p>C. Throat dia to take into account "fat" bullets that are oversize in the pressure ring.</p><p></p><p>NOTE: there are a LOT of mistakes made on clearance at the .200 mark from the bolt face as many make this clearance too tight for the brand of brass they are using, resulting in premature pressure indicator of hard bolt lift, and inability to Full Length resize with standard full-length sizers, This is one heck of a problem. Reloaders need a micrometer that measures to the .0001.</p><p></p><p>When a guy has a reamer that cuts for example .470 dimension at the .200 mark, then his brass measures .469, he is in for one heck of a mess, and the solution is going to a brand of brass that is .466 in the .200 mark, or trying to find a Small Base sizer for that brand of brass.</p><p></p><p>Some of the bullet companies are running their bullet-making dies to produce Fat bullets where the pressure ring is .001 over. It is not unusual to find bullets .0005 over as they are referred to Fat bullets, but to get .0010 over is a problem. For example, In my 6 Dasher varmint rifle, my throat dia is .2435, a typical throat dimension. I was having problems with a particular lot# of bullets, measured them with my micrometer, and they are .244 in the pressure ring. The bullet was being sized down as it went through the throat section, creating premature pressure spikes and simply not shooting worth a darn.</p><p></p><p>While oversize FAT bullets are not the norm, as production gets sloppy, it would pay a reloader to establish some of his own quality control.</p><p></p><p>THE major issue many face is the Web dia, new brass, fired brass, Resize dimension, and reamer/chamber dimensions. Factory rifles have more Liberal tolerances as a norm, but I have seen several undersize/tight factory chambers. All of my hunting rifles shoot some darn hot pressures at the top-end accuracy node where groups are in a Bug Hole.</p><p></p><p>European brass vs American brass, a subject for another topic</p><p></p><p>Elkaholic's problem is similar to what most go through, trying to fit a 10 lb bag of crap in a 5 lb hole. I ran into this for the first time on a 7 STW reamer that I designed to have .002 clearance in the web over new Winchester factory brass dimensions. .002 was nowhere near enough clearance, so as a fix, I was able to get one of the last 7 STW Small base sizers that came out of their custom shop that no longer exists. I got a true 0.0015 smaller case resized dimension(after spring back)vs fired brass dimension, which cycled brass just fine. </p><p></p><p>I am going to shut up for now but this problem has plagued me for 20 years on many cases. If I were rich, I could just order more reamers, but I am not, I have to figure out how to make things work where I can shoot the accuracy node the barrel likes on the cheap. This web dimension is the root cause of the misunderstandings with some using belted magnums as their chambers were just too small for their brass dimensions.</p><p></p><p>Another issue, just because a reamer print has a particular number on it, does not mean that is the dimension you get in your finished barrel due to:</p><p></p><p>Reamer wear</p><p></p><p>Gunsmithing techniques used to chamber the barrel</p><p></p><p>Reamer makers have +/-.0005 tolerance in dimensions they grind to</p><p></p><p>These three things can stack up, leading to a real mess to deal with, been there, done that!.</p></blockquote><p></p>
[QUOTE="VinceMule, post: 2853247, member: 122164"] Mike, I know you are advanced in your thinking and planning, but for those that are not, you take this drawing, make measurments on brand new brass, there is a LOT of design that still needs to be taken into account. If you have a reamer made off of exact brass dimensions, your reamer will be worthless. The print with the exact dimensions is the road map for you to now ADD clearances you want. Knowing what dimensions your dies size to is of great importance, instead of discovering a major flaw AFTER THE FACT! You can actually make a chamber cast of the full length sizing die with Cero Safe if you are a nit pickers, nit picker. Another issue, brass over a lot of 100 pieces may vary slightly in variations, and you need to establish a "spread" on the +/-. Lapua Peterson Alpha Winchester have some very, very dramatic differences in dimensions, especially in the web thickness and neck thickness. Places where many make mistakes including myself: A. New brass dimension .200 from the bolt face, Clearance needed B. Neck dia C. Throat dia to take into account "fat" bullets that are oversize in the pressure ring. NOTE: there are a LOT of mistakes made on clearance at the .200 mark from the bolt face as many make this clearance too tight for the brand of brass they are using, resulting in premature pressure indicator of hard bolt lift, and inability to Full Length resize with standard full-length sizers, This is one heck of a problem. Reloaders need a micrometer that measures to the .0001. When a guy has a reamer that cuts for example .470 dimension at the .200 mark, then his brass measures .469, he is in for one heck of a mess, and the solution is going to a brand of brass that is .466 in the .200 mark, or trying to find a Small Base sizer for that brand of brass. Some of the bullet companies are running their bullet-making dies to produce Fat bullets where the pressure ring is .001 over. It is not unusual to find bullets .0005 over as they are referred to Fat bullets, but to get .0010 over is a problem. For example, In my 6 Dasher varmint rifle, my throat dia is .2435, a typical throat dimension. I was having problems with a particular lot# of bullets, measured them with my micrometer, and they are .244 in the pressure ring. The bullet was being sized down as it went through the throat section, creating premature pressure spikes and simply not shooting worth a darn. While oversize FAT bullets are not the norm, as production gets sloppy, it would pay a reloader to establish some of his own quality control. THE major issue many face is the Web dia, new brass, fired brass, Resize dimension, and reamer/chamber dimensions. Factory rifles have more Liberal tolerances as a norm, but I have seen several undersize/tight factory chambers. All of my hunting rifles shoot some darn hot pressures at the top-end accuracy node where groups are in a Bug Hole. European brass vs American brass, a subject for another topic Elkaholic's problem is similar to what most go through, trying to fit a 10 lb bag of crap in a 5 lb hole. I ran into this for the first time on a 7 STW reamer that I designed to have .002 clearance in the web over new Winchester factory brass dimensions. .002 was nowhere near enough clearance, so as a fix, I was able to get one of the last 7 STW Small base sizers that came out of their custom shop that no longer exists. I got a true 0.0015 smaller case resized dimension(after spring back)vs fired brass dimension, which cycled brass just fine. I am going to shut up for now but this problem has plagued me for 20 years on many cases. If I were rich, I could just order more reamers, but I am not, I have to figure out how to make things work where I can shoot the accuracy node the barrel likes on the cheap. This web dimension is the root cause of the misunderstandings with some using belted magnums as their chambers were just too small for their brass dimensions. Another issue, just because a reamer print has a particular number on it, does not mean that is the dimension you get in your finished barrel due to: Reamer wear Gunsmithing techniques used to chamber the barrel Reamer makers have +/-.0005 tolerance in dimensions they grind to These three things can stack up, leading to a real mess to deal with, been there, done that!. [/QUOTE]
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