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Howa .338 edge?
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<blockquote data-quote="Fiftydriver" data-source="post: 484313" data-attributes="member: 10"><p>The 338 Norma Magnum, if loaded with the same bullet to the same pressures as the 338 Lapua magnum will produce nearly exactly the same bolt thrust on the receiver.</p><p> </p><p>I used to build alot of Rem 700s modified to be chambered for the Lapua class chamberings, namely my 7mm Allen Magnum, 300 Allen Xpress, 338 Allen Xpress and 375 Allen Xpress.</p><p> </p><p>I did some testing with a stainless steel Rem 700 with the 300 AX and after 700 rounds down the barrel, most of them being the 240 gr SMK loaded to 3200 fps in a 30" Lilja 1-8 twist barrel. I pulled the barrel and measured the receiver for bolt lug set back into the receiver supports. After 700 rounds, the stainless steel receiver had roughly 7 thou of bolt lug set back. Bolt lift was starting to get tight at around 500 rounds down the barrel and really noticable after that. Nothing that kept the bolt from opening but it did not matter what load I used, bolt lift was stiff, extraction was effortless, pressures moderate.</p><p> </p><p>This prompted me to check for bolt lug set back.</p><p> </p><p>After seeing this, I fitted the same barrel to a Chrome Moly rem 700. Hammered down another 700 rounds and then pulled the barrel to check the bolt lug setback. Less then 2 thou. Bolt lift had remained excellent throughout testing.</p><p> </p><p>The harder chrome moly steel resisted bolt lug set back much better then the stainless steel receiver when using the same load and chambering. More then three times less set back. At this point I decided to use ONLY chrome moly Rem 700s for my Lapua class builds.</p><p> </p><p>A year or so passed and a customer sent me back his 7mm AM that had been built on a chrome moly receiver. It seems he had been loading this rifle up to the limits of the Lapua case with the 160 gr Accubond and was getting north of 3550 fps in a 30" barrel length. After 300 rounds, bolt lift had become very heavy with all shots. Hearing this I told him to stop shooting the rifle and send it back to me for inspection ASAP.</p><p> </p><p>He did, I pulled the barrel and the bolt lugs has set back into the receiver supports by 10 thou!!!!!</p><p> </p><p>Now these loads that had been used were far over what I had recommended. At that time, I had only loaded the 7mm AM up to around 3450 fps max in the Rem 700 based rifles. He took the load development higher and since there were no pressure signs with his loads and the Lapua brass, he figured they were perfectly safe.</p><p> </p><p>This made it clear that the Rem 700 was not a good choice for this class of chambering. If the Lapua class chamberings are loaded to the 65,000 psi range, a properly built Rem 700 Chrome Moly receiver will handle them easily.</p><p> </p><p>The problem lies in the fact that the Lapua case can support dramatically higher chamber pressures then this and when that case strength is combined with a bit of an unexperienced handloader, the receiver is stressed more then it was ever designed to be. </p><p> </p><p>It was also because of the very strong Lapua case that I have done all my load development for my wildcats based on the Lapua case with the Norma Brand of brass which is significantly softer then the Lapua and will loosen primer pockets at nearly identical pressures and the Reminton RUM brass cases, which is in the 65K to 68K psi range. Once those loads were determined in the norma brass, I could then move over to the Lapua brass and get extremely long case life.</p><p> </p><p>Seeing the potential of the Lapua case to handle pressures that were far above the design goals of the Rem 700, I made the decision to stop offering my Lapua class wildcats on that receiver platform and that was the start of the APS Raptor receiver.</p><p> </p><p>In comparision, I have inspected several 338 Edge rifles with well over 1000 rounds down the barrels in both chrome moly and stainless steel and neither had bolt lug set back much more then 2 thou if that. </p><p> </p><p>Hope this puts some perspective on what can happen when the Rem 700 is overloaded with a Lapua class chambering.</p></blockquote><p></p>
[QUOTE="Fiftydriver, post: 484313, member: 10"] The 338 Norma Magnum, if loaded with the same bullet to the same pressures as the 338 Lapua magnum will produce nearly exactly the same bolt thrust on the receiver. I used to build alot of Rem 700s modified to be chambered for the Lapua class chamberings, namely my 7mm Allen Magnum, 300 Allen Xpress, 338 Allen Xpress and 375 Allen Xpress. I did some testing with a stainless steel Rem 700 with the 300 AX and after 700 rounds down the barrel, most of them being the 240 gr SMK loaded to 3200 fps in a 30" Lilja 1-8 twist barrel. I pulled the barrel and measured the receiver for bolt lug set back into the receiver supports. After 700 rounds, the stainless steel receiver had roughly 7 thou of bolt lug set back. Bolt lift was starting to get tight at around 500 rounds down the barrel and really noticable after that. Nothing that kept the bolt from opening but it did not matter what load I used, bolt lift was stiff, extraction was effortless, pressures moderate. This prompted me to check for bolt lug set back. After seeing this, I fitted the same barrel to a Chrome Moly rem 700. Hammered down another 700 rounds and then pulled the barrel to check the bolt lug setback. Less then 2 thou. Bolt lift had remained excellent throughout testing. The harder chrome moly steel resisted bolt lug set back much better then the stainless steel receiver when using the same load and chambering. More then three times less set back. At this point I decided to use ONLY chrome moly Rem 700s for my Lapua class builds. A year or so passed and a customer sent me back his 7mm AM that had been built on a chrome moly receiver. It seems he had been loading this rifle up to the limits of the Lapua case with the 160 gr Accubond and was getting north of 3550 fps in a 30" barrel length. After 300 rounds, bolt lift had become very heavy with all shots. Hearing this I told him to stop shooting the rifle and send it back to me for inspection ASAP. He did, I pulled the barrel and the bolt lugs has set back into the receiver supports by 10 thou!!!!! Now these loads that had been used were far over what I had recommended. At that time, I had only loaded the 7mm AM up to around 3450 fps max in the Rem 700 based rifles. He took the load development higher and since there were no pressure signs with his loads and the Lapua brass, he figured they were perfectly safe. This made it clear that the Rem 700 was not a good choice for this class of chambering. If the Lapua class chamberings are loaded to the 65,000 psi range, a properly built Rem 700 Chrome Moly receiver will handle them easily. The problem lies in the fact that the Lapua case can support dramatically higher chamber pressures then this and when that case strength is combined with a bit of an unexperienced handloader, the receiver is stressed more then it was ever designed to be. It was also because of the very strong Lapua case that I have done all my load development for my wildcats based on the Lapua case with the Norma Brand of brass which is significantly softer then the Lapua and will loosen primer pockets at nearly identical pressures and the Reminton RUM brass cases, which is in the 65K to 68K psi range. Once those loads were determined in the norma brass, I could then move over to the Lapua brass and get extremely long case life. Seeing the potential of the Lapua case to handle pressures that were far above the design goals of the Rem 700, I made the decision to stop offering my Lapua class wildcats on that receiver platform and that was the start of the APS Raptor receiver. In comparision, I have inspected several 338 Edge rifles with well over 1000 rounds down the barrels in both chrome moly and stainless steel and neither had bolt lug set back much more then 2 thou if that. Hope this puts some perspective on what can happen when the Rem 700 is overloaded with a Lapua class chambering. [/QUOTE]
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