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Rifles, Reloading, Optics, Equipment
Gunsmithing
secrets of straightening a barrel
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<blockquote data-quote="Trickymissfit" data-source="post: 510862" data-attributes="member: 25383"><p>most barrel makers are still using Pratt-Whitney gun drills from the 1950's. There are a few others out there, but most folks refuse to change, and for the most part are not anybetter. I'm not sure what they used in WWII for tooling, but I'm certain that many used the P&W's. The big difference between then and now is in the tooling, and cutting fluids (note I consider the bushing box and coolant system as tooling with these things). Drill grinds are very secretive, and often are reground off of brand new drills. How they are doing their reaming processes I can say, but it looks to me like they might be infringing on the Mapol Reamer copyrights (an extremely accurate reamer, but also very costly). The coolant is also closely guarded, and often custom mixed. The system will usually be multi filtered with at least one redundent filter system standing by. They are always at least 75 gallons and some are as big as 350 gallons. They run in a similar fashion as the basic hydraulic systems do with the same type of pumps. The grind and the bushing box are major players in keeping the bores strait and on size, and they are hydraulicly loaded with coolant and very high pressures.</p><p> </p><p>Right now Eldorado is the new kid on the block (actually since the very late 1970's), but the technology is the same. They are extremely accurate, and make gun drill that drill from both ends at the sametime. Only to meet in the middle.</p><p> </p><p>If tooled up right the blank should come out very strait (less than .0075"). But that becomes another problem as the steel lets go of it's stress as you drill; causing warpage as the drill goes thru. I looked at some photos awhile back of a barrel straitening machine in the Savage shop. Interesting, but I asked myself why? They now make machines that you can put the barrel in it, and it will do the job within .0005" in less than a minute! With very little stress involved I might add. Of course the big guys say you should never straiten a barrel after it's finished out. These guys always amaze me at how well they can cut a bore</p><p>gary</p></blockquote><p></p>
[QUOTE="Trickymissfit, post: 510862, member: 25383"] most barrel makers are still using Pratt-Whitney gun drills from the 1950's. There are a few others out there, but most folks refuse to change, and for the most part are not anybetter. I'm not sure what they used in WWII for tooling, but I'm certain that many used the P&W's. The big difference between then and now is in the tooling, and cutting fluids (note I consider the bushing box and coolant system as tooling with these things). Drill grinds are very secretive, and often are reground off of brand new drills. How they are doing their reaming processes I can say, but it looks to me like they might be infringing on the Mapol Reamer copyrights (an extremely accurate reamer, but also very costly). The coolant is also closely guarded, and often custom mixed. The system will usually be multi filtered with at least one redundent filter system standing by. They are always at least 75 gallons and some are as big as 350 gallons. They run in a similar fashion as the basic hydraulic systems do with the same type of pumps. The grind and the bushing box are major players in keeping the bores strait and on size, and they are hydraulicly loaded with coolant and very high pressures. Right now Eldorado is the new kid on the block (actually since the very late 1970's), but the technology is the same. They are extremely accurate, and make gun drill that drill from both ends at the sametime. Only to meet in the middle. If tooled up right the blank should come out very strait (less than .0075"). But that becomes another problem as the steel lets go of it's stress as you drill; causing warpage as the drill goes thru. I looked at some photos awhile back of a barrel straitening machine in the Savage shop. Interesting, but I asked myself why? They now make machines that you can put the barrel in it, and it will do the job within .0005" in less than a minute! With very little stress involved I might add. Of course the big guys say you should never straiten a barrel after it's finished out. These guys always amaze me at how well they can cut a bore gary [/QUOTE]
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