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<blockquote data-quote="Brent" data-source="post: 69695" data-attributes="member: 99"><p>AJ,</p><p></p><p>.050 shorter on the throat should not make too much difference in pressure. </p><p></p><p>What is the max OAL you can seat the 200 AB out to? Where does it contact the lands? </p><p></p><p>With my factory chamber it touches at 3.835, I think, so if yours contacts at 3.785 or so it wouldn't be much difference.</p><p></p><p>What is your barrel's inside diameter under the gage?</p><p></p><p>What is the fired case diameter under the gage? </p><p></p><p>You could be down in the high 50 Kpsi range but I suspect it's in the low 60 Kpsi range, possibly due to a thinner than actual chamber wall being figured in the calculations.</p><p></p><p>It seems to me that I remember Burt suggesting in the PT program documentation that he recommends adding .003" to the fired case diameter directly under the gage location to get the actual bbl ID. The reasoning is the brass springs back slightly when it cools and the chamber will be slightly larger than the case you measure, thus the barrel's wall thickness is a tad thinner. </p><p></p><p>Using the Oehler M43 for some time before getting the PT unit I never had to add any amount to the case diameter though, so I never did with PT either. I think the case does cool and shrink slightly, but it's on the order of .0005, to .001 maybe, it's not much though. </p><p></p><p>If you use the case diameter at the gage location as the actual barrel ID and don't add .003 to it, you will in effect be telling the program that the chamber wall is thicker. Now if the chamber wall is thicker but, the gage reads the same micro-strain, it will indicate pressure is slightly higher now. To get the same micro-strain on a thicker pressure vessel, the pressure must be higher, this is how that works. You can go in and manipulate the barrel ID on an existing test and see how it affects peak pressure. In doing so, you are simply telling the program that this barrel was actually thinner and to modify calculations to reflect the new chamber wall thickness. </p><p></p><p>It's been quite a while since I've played with the program much so I'd have to run through it on my own first to remember exactly how this is done, and if it applies to all tests with the same barrel or just the one you happen to be playing around with. After some extensive testing with PT in the begining stages there was some language added/modified in the pop-up windows that made it more easily understood what was being altered and to keep one from accidentally modifying a test without realizing they had. </p><p></p><p>I worked with Burt for quite a long time finding bugs with the program and getting many key features added and changed to benifit the guy using it, and I can tell you this is the most I've ever seen anyone work to perfect a program and make it the best it could ever be. The guy was relentless in wanting it to be the best on the market, and doing anything and everything fast to make it happen. This guy is simply amazing! If you guys only knew what he went through to make this product what it is today you'd ****! Sure he wants to sell it for profit but, it goes far deeper than that and is a serious passion of his to offer nothing but the best of the best leading edge products at a fair price, all with outstanding customer service and support. Burt and Jim are just outstanding people and we're pretty lucky to have these two putting their heads together and offering these awesome products, at bargin prices I might add. </p><p></p><p>Seriously, don't hesitate to call them either if you have any questions, they certainly can help walk you through any problem you might ever encounter. They are just as willing as they are able too. </p><p></p><p>I'll help where I can too, for sure, just give me a shout.</p></blockquote><p></p>
[QUOTE="Brent, post: 69695, member: 99"] AJ, .050 shorter on the throat should not make too much difference in pressure. What is the max OAL you can seat the 200 AB out to? Where does it contact the lands? With my factory chamber it touches at 3.835, I think, so if yours contacts at 3.785 or so it wouldn't be much difference. What is your barrel's inside diameter under the gage? What is the fired case diameter under the gage? You could be down in the high 50 Kpsi range but I suspect it's in the low 60 Kpsi range, possibly due to a thinner than actual chamber wall being figured in the calculations. It seems to me that I remember Burt suggesting in the PT program documentation that he recommends adding .003" to the fired case diameter directly under the gage location to get the actual bbl ID. The reasoning is the brass springs back slightly when it cools and the chamber will be slightly larger than the case you measure, thus the barrel's wall thickness is a tad thinner. Using the Oehler M43 for some time before getting the PT unit I never had to add any amount to the case diameter though, so I never did with PT either. I think the case does cool and shrink slightly, but it's on the order of .0005, to .001 maybe, it's not much though. If you use the case diameter at the gage location as the actual barrel ID and don't add .003 to it, you will in effect be telling the program that the chamber wall is thicker. Now if the chamber wall is thicker but, the gage reads the same micro-strain, it will indicate pressure is slightly higher now. To get the same micro-strain on a thicker pressure vessel, the pressure must be higher, this is how that works. You can go in and manipulate the barrel ID on an existing test and see how it affects peak pressure. In doing so, you are simply telling the program that this barrel was actually thinner and to modify calculations to reflect the new chamber wall thickness. It's been quite a while since I've played with the program much so I'd have to run through it on my own first to remember exactly how this is done, and if it applies to all tests with the same barrel or just the one you happen to be playing around with. After some extensive testing with PT in the begining stages there was some language added/modified in the pop-up windows that made it more easily understood what was being altered and to keep one from accidentally modifying a test without realizing they had. I worked with Burt for quite a long time finding bugs with the program and getting many key features added and changed to benifit the guy using it, and I can tell you this is the most I've ever seen anyone work to perfect a program and make it the best it could ever be. The guy was relentless in wanting it to be the best on the market, and doing anything and everything fast to make it happen. This guy is simply amazing! If you guys only knew what he went through to make this product what it is today you'd ****! Sure he wants to sell it for profit but, it goes far deeper than that and is a serious passion of his to offer nothing but the best of the best leading edge products at a fair price, all with outstanding customer service and support. Burt and Jim are just outstanding people and we're pretty lucky to have these two putting their heads together and offering these awesome products, at bargin prices I might add. Seriously, don't hesitate to call them either if you have any questions, they certainly can help walk you through any problem you might ever encounter. They are just as willing as they are able too. I'll help where I can too, for sure, just give me a shout. [/QUOTE]
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