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The Basics, Starting Out
Action for .338 Lapua
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<blockquote data-quote="Steve Shelp" data-source="post: 52375" data-attributes="member: 22"><p>Chris,</p><p> Understood and let me say up front there was never any intent of a "contest" from my perspective either. Below is my thoughts on this.</p><p></p><p><strong> understand what you are saying about the margin of safety, and I agree that it is up to a person to decide how</strong></p><p><strong>much he or she needs.</strong></p><p>That's really all I really wanted to state by making the post above. We're here to talk about LRH and acccurate rifles. As long as people have info from boths side of this debate to makeup thier own minds, is all I really wanted.</p><p></p><p><strong>But the case will not stretch due to lack of support.</strong></p><p>I disagree with that and here's why. I went and dug up the article that I referenced above that Jim Bordon wrote to make sure I had my facts straight and not relaying on memory. What Jim found when using 404 cases in minimum chambers in M70 actions is the barrel tenon stub of the M70 action would expand a certain amount due to elasticity and the brass case would expand with it. Then the steel would want to snap back back more than the brass and cause very tight extraction of the case. It was litterly causing a shrink fit of the case head in the chamber due to the lack of support of steel around the case head. This would only happen in tight chambers when the chamber was cut .002 or less larger in diameter than the sized cases. He didn't reference the brand of 404 cases this was found with though. </p><p> So with the 404 case your talking a case head of .540"?? and a nominal tenon diameter of 1" (leaving out the actual root thread diameter to keep it simple) on the M70 action. Now you take a Remington 1 1/6 tenon thread diameter which is .060 larger than a Win M70 and add in a case that is roughly .040" larger in diameter you end up with a little better barrel tenon -to- case head diameter ratio so it would be better than the M70 with all else being equal. Plus the toughness of these Lapua 338 cases is unbeleivable. My Norma brass shows pressure and extraction problems before the Lapua stuff I have. Just making sure everyone is aware that this can happen. Please don't misunderstand this to say it is happening in this M700/338 Lapua scenerio. Jim has the calculations in the article that I went back and dug up, so if someone is interested I can send it to them for thier own curiosity. But it does happen under certain circumstances.</p><p></p><p><strong>The recess into the breech on a Rem. is typically 0.150" deep, if you measure the extractor groove on 338 Lapua brass it is about 0.130" from the start of the groove to the back of the head. This means that the whole case would be supported inside the chamber . I don't know of any cartridge(rimless) that the extractor groove is fully supported by the chamber.</strong></p><p>agreed. No case is supported 100% becasue of the mechanical action of having to grab the case to extract it from the chamber.</p><p></p><p><strong> If the chamber is headspaced properly how or where is this case going to stretch?</strong></p><p>see explaination above. This same concept is also the reason you have to shoulder bump cases after several firings. The case can not get bigger than the container it is inside of, unless the container (the chamber) grows upon firing then returns to it's original size and crushes the brass case. This is the stickness you feel upon extraction.</p><p></p><p><strong>I am not claiming to be an expert gunsmith but I get my info from the expert's.</strong></p><p>I'm not either. Sounds like you and I work on the same principles. Jim Bordon has a pretty respectable list of engineering/gunsmithing credentials also among other repsectable LR smiths I know.</p><p></p><p><strong>As far as lug set back- I have personally seen a Rem action on it's SECOND barrel chambered for the Lapua. The second barrel has over two thousand rounds through it. Abusolutely NO measurable setback.</strong></p><p>Remington actions do setback and it has been observed more than once. When and why it happens to one action and not another...? I don't know and really can't exlain it either. Stacking of tolerenaces, variance of heat treating, etc, etc??? It does happen so I stay on the side of keeping a large safety margin to begin with. I don't doubt you do have an action with no setback and can't and won't disagree with you. </p><p></p><p><strong>Like I said I'm not trying to start a ****ing match, but simply pass along info and maybe clear up a misconception.</strong></p><p>same here Chris I just happen to sit on the opposite side of the table from you on this issue. If you beleive this can be done and want to do it beleive me I won't stop you and hope you continue to have fun shooting with your wife. I wish mine would take more interest in shooting, but she just won't take the bait. I keep buying guns for her though! ;^) The professionalism and experience of people on this message board is great, but this is a public forum and you never know if someone less educated in guns reads this and has a local smith that doesn't have the experience of the people you and I deal with, build one of these combos and run into problems. That is really the basis for my posting here to begin with. Definitely don't want to cause problems. You and I are square as far as I'm concerned.</p><p></p><p>I'm a lefty also and will not shoot a RH Remington action with a Sako extractor in it. Yes I've heard the statement that the extractor is turned down under the lug abutment and is out of sight upon firing. But if the "stuff" hits the fan the weakest link will be exposed and chances are metal will be coming out the side of the action in front of my face. So 308 Hawg and I are on the same page with that thought.</p><p> My 6.5-300 Win Mag has a RH Sako solid bottom AIII action with obvously a Sako extractor on it. But one thing Sako installs is the rail going down the side of bolt that looks like the long claw extractor of an old Mauser that will help block any metal from coming out that side of the action just in case. So I feel more comfortable shooting this action over the Remington in RH configuration with the Sako extractor.</p><p></p><p>Hope this clears some things up. Gotta go to work now it's almost 12:30.</p><p></p><p>Steve</p></blockquote><p></p>
[QUOTE="Steve Shelp, post: 52375, member: 22"] Chris, Understood and let me say up front there was never any intent of a "contest" from my perspective either. Below is my thoughts on this. [B] understand what you are saying about the margin of safety, and I agree that it is up to a person to decide how much he or she needs.[/B] That's really all I really wanted to state by making the post above. We're here to talk about LRH and acccurate rifles. As long as people have info from boths side of this debate to makeup thier own minds, is all I really wanted. [B]But the case will not stretch due to lack of support.[/B] I disagree with that and here's why. I went and dug up the article that I referenced above that Jim Bordon wrote to make sure I had my facts straight and not relaying on memory. What Jim found when using 404 cases in minimum chambers in M70 actions is the barrel tenon stub of the M70 action would expand a certain amount due to elasticity and the brass case would expand with it. Then the steel would want to snap back back more than the brass and cause very tight extraction of the case. It was litterly causing a shrink fit of the case head in the chamber due to the lack of support of steel around the case head. This would only happen in tight chambers when the chamber was cut .002 or less larger in diameter than the sized cases. He didn't reference the brand of 404 cases this was found with though. So with the 404 case your talking a case head of .540"?? and a nominal tenon diameter of 1" (leaving out the actual root thread diameter to keep it simple) on the M70 action. Now you take a Remington 1 1/6 tenon thread diameter which is .060 larger than a Win M70 and add in a case that is roughly .040" larger in diameter you end up with a little better barrel tenon -to- case head diameter ratio so it would be better than the M70 with all else being equal. Plus the toughness of these Lapua 338 cases is unbeleivable. My Norma brass shows pressure and extraction problems before the Lapua stuff I have. Just making sure everyone is aware that this can happen. Please don't misunderstand this to say it is happening in this M700/338 Lapua scenerio. Jim has the calculations in the article that I went back and dug up, so if someone is interested I can send it to them for thier own curiosity. But it does happen under certain circumstances. [B]The recess into the breech on a Rem. is typically 0.150" deep, if you measure the extractor groove on 338 Lapua brass it is about 0.130" from the start of the groove to the back of the head. This means that the whole case would be supported inside the chamber . I don't know of any cartridge(rimless) that the extractor groove is fully supported by the chamber.[/B] agreed. No case is supported 100% becasue of the mechanical action of having to grab the case to extract it from the chamber. [B] If the chamber is headspaced properly how or where is this case going to stretch?[/B] see explaination above. This same concept is also the reason you have to shoulder bump cases after several firings. The case can not get bigger than the container it is inside of, unless the container (the chamber) grows upon firing then returns to it's original size and crushes the brass case. This is the stickness you feel upon extraction. [B]I am not claiming to be an expert gunsmith but I get my info from the expert's.[/B] I'm not either. Sounds like you and I work on the same principles. Jim Bordon has a pretty respectable list of engineering/gunsmithing credentials also among other repsectable LR smiths I know. [B]As far as lug set back- I have personally seen a Rem action on it's SECOND barrel chambered for the Lapua. The second barrel has over two thousand rounds through it. Abusolutely NO measurable setback.[/B] Remington actions do setback and it has been observed more than once. When and why it happens to one action and not another...? I don't know and really can't exlain it either. Stacking of tolerenaces, variance of heat treating, etc, etc??? It does happen so I stay on the side of keeping a large safety margin to begin with. I don't doubt you do have an action with no setback and can't and won't disagree with you. [B]Like I said I'm not trying to start a ****ing match, but simply pass along info and maybe clear up a misconception.[/B] same here Chris I just happen to sit on the opposite side of the table from you on this issue. If you beleive this can be done and want to do it beleive me I won't stop you and hope you continue to have fun shooting with your wife. I wish mine would take more interest in shooting, but she just won't take the bait. I keep buying guns for her though! ;^) The professionalism and experience of people on this message board is great, but this is a public forum and you never know if someone less educated in guns reads this and has a local smith that doesn't have the experience of the people you and I deal with, build one of these combos and run into problems. That is really the basis for my posting here to begin with. Definitely don't want to cause problems. You and I are square as far as I'm concerned. I'm a lefty also and will not shoot a RH Remington action with a Sako extractor in it. Yes I've heard the statement that the extractor is turned down under the lug abutment and is out of sight upon firing. But if the "stuff" hits the fan the weakest link will be exposed and chances are metal will be coming out the side of the action in front of my face. So 308 Hawg and I are on the same page with that thought. My 6.5-300 Win Mag has a RH Sako solid bottom AIII action with obvously a Sako extractor on it. But one thing Sako installs is the rail going down the side of bolt that looks like the long claw extractor of an old Mauser that will help block any metal from coming out that side of the action just in case. So I feel more comfortable shooting this action over the Remington in RH configuration with the Sako extractor. Hope this clears some things up. Gotta go to work now it's almost 12:30. Steve [/QUOTE]
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Action for .338 Lapua
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