MMACFIVE Report post Posted December 20, 2015 I had soo much fun in my last post "Is Sectional Density by itself worthless" that I just have to give it one more try. I've always been attracted to non main stream cartridges like the 257 Roberst, 6.5x55 swede, the 280 Remington, etc. Often these cartridges are not loaded to their full potential because of older actions (or Remington's screw up!) I will use the 30-06 as am example parent case: Cartridge SAAMI PSI 25-06 63,000 6.5-06 A Square 65,000 270 Win 65,000 280 Rem 60,000 30-06 60,000 338-06 A Square 63,000 35 Whelen 63,000 It makes sense to me that If Everything IS Held Constant (file, bullets construction, brass, etc.) than the chamber pressure should be the same. So for many years I have made the assumption that if you are shooting within a "Parent" case that all calibers should shoot a bullets with the same SD at the same velocity (Again this is assuming that everything but the diameter is the same across the bullets!) Part of my assumption is that sense SD is a mathematical representation of the bullets weight and diameter it will partly account for things like bearing surface and expansion ratio. So far this has worked out very well for me..or maybe I've just got lucky. I would like to hear constructive challenge of this theorem. And I'd like to thank 308nut for his healthy input into my last post. Mike Share this post Link to post Share on other sites
WampusCat Report post Posted December 21, 2015 So far this has worked out very well for me..or maybe I've just got lucky. What specifically has worked out very well for you? After reading your posts, (8 of currently 31 that were just periods bumping the page to the top) I am still not sure what your angle is? What are you trying to prove? SD has its place. It is not the only thing to measure a projectiles ability. It is just single measurement in the equation. No one here has stated anything different. Unless your definition of everything is different than mine... When EVERYTHING is held constant, everything WILL stay the same. 1 Share this post Link to post Share on other sites
trphyhntr Report post Posted December 21, 2015 Wtf am I reading 2 Share this post Link to post Share on other sites
MMACFIVE Report post Posted December 21, 2015 I'm sorry. I don't mean to come across that I need to prove anything. I've just been operating under the theory that a given case capacity should shoot a bullet with the same SD the same velocity. All I wanted was some independent challenge to see if I am way off base. I use the case capacity theory with different cartridges also. My 300 H&H is about the same capacity as the 300 Win mag so I cross reference those loads. There are often more up to date loads with the newer powders with the more popular cartridges. For example Nosler just published a bunch of loads for their new 28 Nosler. They probably won't update my 7mm STW any time soon but since the case capacity between the 2 cases is within about 1 grain I can use the new 28 Nosler data as a reference for my STW. As for what specifically has worked out well for me? I just bought a Forbes 24b in 6.5x55. As most know this cartridge is loaded to very low specs because of some of the old actions. I should be able to load it to the same pressures as the 25-06 and 270 win since they are also loaded in the same gun. With my O.C.L. I calculated my usable volume (54g) to be between the 260 rem and the 6.5x284, therefore I should expect my velocities to represent that. I am getting 3000fps with a 130 NAB from the Forbes with no pressure signs so it worked out for me in this case. I also want to apologize for the period bumps....they weren't intentional. Just pure exasperation trying to learn a new editing system that would not let me do what I thought it should....but I did learn how to bump to the top! Share this post Link to post Share on other sites
lancetkenyon Report post Posted December 21, 2015 Just because a family of cartridges uses the same parent case (the 06 family) does not mean each one shooting a bullet of the same SD will shoot the same velocity. Bullet weight vs. powder charge weight will negate this. Take a .25-06 shooting a 117gr. SGK Bullet at 3100 fps over 58gr. of powder vs. a .30-06 shooting a 168 gr. TMK bullet over 58gr. of powder at 2900fps. Both have anot SD of .253. Also, at distances over 599 yards, your penetration is going to drastically change due to velocity and energy remaining on target. I have not done a lot of research on SD, but I know what I have witnessed on game from various bullets. SD depends so much on bullet construction and design, you have to pick what you prefer. Deep penetration, smaller expansion, high weight retention, or less penetration, better usage of energy, frangible bullets for a wider wound channel. Personally, I have never even looked at SD when choosing a bullet for hunting. 1 Share this post Link to post Share on other sites
MMACFIVE Report post Posted December 21, 2015 I totally agree with you on your SD paragraph. Well said. If my parent case capacity theory was absolutely accurate it would say that you are driving the 25 too hot or the 30-06 not not enough. I've shot enough 120s out of the 25-06 to know that is a reasonable velocity. And I've shot enough 30-06 to know I can't safely get 3100 with a 168. But my theory makes me think there is some place in the middle with the 30-06. I can get about 3000 with the 168's. Remember I am assuming I can load an additional 5kPSI pressure safely in the 06. With Hodgdon Superformace I just might get close to 3100 with the 168s....HSP works really well in most of the 30-06 size cases. Share this post Link to post Share on other sites
308Nut Report post Posted December 21, 2015 Personally, I think you are doing one of several things (or a combination of them). 1: I think you're trying to learn while at the same time making everybody think you are an expert. 2: You enjoy arguing and proving your smarter and/or more educated than everybody else. 3: You really are smarter and/or more educated than everybody else and you start your threads in a way that makes people think you are looking for knowledge when in reality, you just want to one up them when they make less educated comments than you could. Hopefully I am wrong and you are actually trying to engage in a constructive type of discussion for the benefit of all. Whether or not I am on track here, I will respectfully disengage from these threads. I can see where it is going and it isn't going anywhere good. We're both going to end up looking like jack a??!! There was a time when I did enjoy the battle of wits and knowledge but I really have much better things to do than to go back and forth with no benefit to other readers. I'm not trying to be a prick here, nor do I desire to be one, though it's probably impossible not to be one while trying to convey my message. I do enjoy these forums and threads on shooting. I even do enjoy an occasional constructive argument, especially when opinions are involved. It's pretty hard to win or loose an argument when facts can't be involved or just aren't involved. When facts are involved, the person who is in the wrong looks like an idiot and the person who is right looks like a jack a$$. In many cases, both parties look like both. When it's opinion based, it only gives the guys arguing as well as onlookers more thought provoking ideas to chew on...To me, that is constructive. Best wishes, M 3 Share this post Link to post Share on other sites
AverageJoe Report post Posted December 21, 2015 Everything he is arguing has already been beat to death on other sites. There really is little to nothing new to argue in the long range world. Onto the next fad in the hunting world please. 2 Share this post Link to post Share on other sites
WampusCat Report post Posted December 21, 2015 Personally, I think you are doing one of several things (or a combination of them). 1: I think you're trying to learn while at the same time making everybody think you are an expert. 2: You enjoy arguing and proving your smarter and/or more educated than everybody else. 3: You really are smarter and/or more educated than everybody else and you start your threads in a way that makes people think you are looking for knowledge when in reality, you just want to one up them when they make less educated comments than you could. 4. 2 Share this post Link to post Share on other sites
Tucson John Report post Posted December 21, 2015 OK..............you guys are hurting my head again! 1 Share this post Link to post Share on other sites
lancetkenyon Report post Posted December 21, 2015 I totally agree with you on your SD paragraph. Well said. If my parent case capacity theory was absolutely accurate it would say that you are driving the 25 too hot or the 30-06 not not enough. I've shot enough 120s out of the 25-06 to know that is a reasonable velocity. And I've shot enough 30-06 to know I can't safely get 3100 with a 168. But my theory makes me think there is some place in the middle with the 30-06. I can get about 3000 with the 168's. Remember I am assuming I can load an additional 5kPSI pressure safely in the 06. With Hodgdon Superformace I just might get close to 3100 with the 168s....HSP works really well in most of the 30-06 size cases. Only YOUR gun can tell you the pressure limits, not a scientific formula, book or number. Share this post Link to post Share on other sites
trphyhntr Report post Posted December 22, 2015 Are you guys virgins? 1 Share this post Link to post Share on other sites
5guyshunting Report post Posted December 22, 2015 Are you guys virgins? Are they talkin sexual destiny? 1 Share this post Link to post Share on other sites
lancetkenyon Report post Posted December 22, 2015 Only had sex twice, hence my 2 kids. Share this post Link to post Share on other sites
trphyhntr Report post Posted December 22, 2015 Only had sex twice, hence my 2 kids. potency of the gods. i probably have a couple out there some where Share this post Link to post Share on other sites
