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to chrony or not to chrony? That's my question

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  • #31
    Chrony

    I have one and use it frequently. It is not a necessity but sure helps understand what is going on. When you do not get a tight group the extreme spread will tell you if its the powder. If ES is good, 30 fps/5 rds; look to the bullet. For me, it is worth it. Best wishes. J.

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    • #32
      As to the OPs original question, I would buy a chronograph for fun, not to determine pressure.

      If you are shooting a .375 JDJ, eeking out extra FPS above and beyond what the load books list isn't worth it. If you want more velocity, shoot a different caliber. If you want to save powder, shoot a smaller cartridge. At 150 yards with a big bullet doing the rainbow arc trajectory, I would work up loads for accuracy rather than velocity. Move your charge weights up or down a couple of grains, not to exceed the book and stick with the best grouping. If still not satisfied, go to a different bullet.

      Also, use a current reloading manual, avoid an old (like my 25 year old Speer) manuals. Be careful switching bullets. All can contribute to excessive pressures. Once I used my Nosler Ballistic Tip load for a Nosler Partition load. I'm a little slow and after THREE rounds, which all felt stout and the bolt was a little sticky, I checked the brass. Totally flat primers and bolt face engraving on the case head. Nice group. I bought a Nosler manual and I was several grains over max for the partition. Backed off the load and no more pressure signs. It actually became my best grouping bullet in that gun, even better than the old Ballistic Tip.

      Some guys try to make the 45-70 a 458 WM, or the 30-06 a 300 WM. I have only one set of eyes, hands, and face, and I prefer to keep them OEM.

      :topjob:

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      • #33
        Originally posted by jim in anchorage View Post
        I don't know why so many are afraid of gauging pressure by examining the case. Even Phil Sharpe didn't like it [using the case to read pressure] claiming flat primers where because powder grains had worked their way into the primer pocket trough the flash hole. In a bolt action only the case is the weak link. If it looks good you're ok. Picture a brass case as a CUP piston. the more it deforms the higher the pressure. Is the solid head of the case taking on machine marks from the bolt? Pressure too high, the brass is flowing. MV means nothing.
        Hard to know where to start, but this approach is at best naive. Measuring pressure with copper or lead crushers is an exacting work that requires many controlled components to determine breech pressure. Cartridge cases are of such inconsistency that trying to base pressure readings on their signs is at best tricky and are no way comparable to copper crusher methods because of these many inconsistencies. I've used a strain gauge enough to know that the makeup of the brass is more significant to the characteristics touted as proof of pressure than the actual pressures generated in many instances. However, MV is directly proportional to generated pressures irrespective to the composition of the brass.

        FWIW, I've a 300 WM (24 inch barrel) that will fire 165 SPBT at 3450+ fps without the brass flowing, with an unaltered bolt lift, and perfect looking primers. A properly cut chamber that is square to the bolt fired in a strong rifle simply won't tell me (or anyone else) that the pressure is overloaded by 15-20,000 psi by inspecting the brass. The MV does tell me that, as has a previously attached strain gauge. It is really a very simple concept. Under normal combustion conditions with any given powder, higher velocity indicates higher pressures. I've seen soft brass that leave various "pressure signs" at 85-90% of SAAMI listed maximum average pressure though the "pressure signs" would have had some "experts" foolishly running for cover expecting that the rifle was a bomb with those loads. Handloading is rocket science; trying to take pressure measurements using a divining rod (brass flow, bolt lift, etc.) seems a hopeless method to me, but suum cuique.
        Foolishness is a moral category, not an intellectual one.

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        • #34
          Originally posted by ADfields View Post
          You are correct that CUP (copper units of pressure) are measured by how much the pressure deforms copper. And correct that if you are seeing pressure signs on your case they are indicative of a pressure. However the tricky thing is that not seeing pressure signs on your case is not indicative of lower pressure, in other words you can have excessive pressure and no signs at all on the spent case.

          For CUP testing a known alloy of a known hardness is used then the deformation measured . . . then its thrown away and a new one used for the next test. Rifle brass comes it a thousand alloys and all react differently under pressure. Brass also becomes work hardened from forming, sizing, firing and so on so even the very same piece of brass may react very differently to pressure shot to shot. Iíve seen flattened primers in 357 brass after popping 3g of Bullseye so flat primers means absolutely nothing to me in terms of pressure. Then the reading of all this stuff is very subjective and varies reader to reader. This means reading pressure signs on brass is better than nothing but acutely doesnít tell you very much at all about the real pressure in there.
          No and I thought about the fact that not all brass cases are the same metallurgy and will not give you absolute pressure readings but can tell you that with this case, with this load, in this gun you are pushing the envelope of pressure. If I have, say 500 Federal .223 cases and load to book max and beyond till the spent primers are falling out, then thats max for that lot of brass.
          But thats all I care about in a modern bolt. Some lots of brass will take more pressure then others, no doubt. Thats why I do not mix brass in my loads. All the same lot, or I weigh them.

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          • #35
            Originally posted by 1Cor15:19 View Post
            Hard to know where to start, but this approach is at best naive. Measuring pressure with copper or lead crushers is an exacting work that requires many controlled components to determine breech pressure. Cartridge cases are of such inconsistency that trying to base pressure readings on their signs is at best tricky and are no way comparable to copper crusher methods because of these many inconsistencies. I've used a strain gauge enough to know that the makeup of the brass is more significant to the characteristics touted as proof of pressure than the actual pressures generated in many instances. However, MV is directly proportional to generated pressures irrespective to the composition of the brass.

            FWIW, I've a 300 WM (24 inch barrel) that will fire 165 SPBT at 3450+ fps without the brass flowing, with an unaltered bolt lift, and perfect looking primers. A properly cut chamber that is square to the bolt fired in a strong rifle simply won't tell me (or anyone else) that the pressure is overloaded by 15-20,000 psi by inspecting the brass. The MV does tell me that, as has a previously attached strain gauge. It is really a very simple concept. Under normal combustion conditions with any given powder, higher velocity indicates higher pressures. I've seen soft brass that leave various "pressure signs" at 85-90% of SAAMI listed maximum average pressure though the "pressure signs" would have had some "experts" foolishly running for cover expecting that the rifle was a bomb with those loads. Handloading is rocket science; trying to take pressure measurements using a divining rod (brass flow, bolt lift, etc.) seems a hopeless method to me, but suum cuique.
            Thats why I said one lot of brass.

            Comment


            • #36
              Originally posted by jim in anchorage View Post
              Thats why I said one lot of brass.
              That's why I said suum cuique.
              Foolishness is a moral category, not an intellectual one.

              Comment


              • #37
                No and I thought about the fact that not all brass cases are the same metallurgy and will not give you absolute pressure readings but can tell you that with this case, with this load, in this gun you are pushing the envelope of pressure. If I have, say 500 Federal .223 cases and load to book max and beyond till the spent primers are falling out, then thats max for that lot of brass.
                But thats all I care about in a modern bolt. Some lots of brass will take more pressure then others, no doubt.
                ^^This is why I don't like to shoot at public ranges. You never know when this guy might be at the bench next to you.
                ...he who knows nothing is nearer to truth than he whose mind is filled with falsehoods & errors. ~Thomas Jefferson
                I would rather have a mind opened by wonder than one closed by belief. ~Gerry Spence
                The last thing Alaska needs is another bigot. ~member Catch It

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                • #38
                  Originally posted by jim in anchorage View Post
                  No and I thought about the fact that not all brass cases are the same metallurgy and will not give you absolute pressure readings but can tell you that with this case, with this load, in this gun you are pushing the envelope of pressure. If I have, say 500 Federal .223 cases and load to book max and beyond till the spent primers are falling out, then thats max for that lot of brass.
                  But thats all I care about in a modern bolt. Some lots of brass will take more pressure then others, no doubt. Thats why I do not mix brass in my loads. All the same lot, or I weigh them.
                  So because its brass from the same lot hardness case to case will be consistent? Well it isnít at all consistent, these lots are treated in a huge basket thousands of cases at a time. The ones in the center get a far different heat cycle than those outside, top varies greatly from bottom and so on.


                  Loads can be safely made without a chronograph; I did it for many years myself. But When you get tools you quickly see just how mislead you were.

                  And for the record never EVER exceed max data!!!!!!!
                  Andy
                  On the web= C-lazy-F.co
                  Email= Andy@C-lazy-F.co
                  Call/Text 602-315-2406
                  Phoenix Arizona

                  Comment


                  • #39
                    Originally posted by ADfields View Post
                    Loads can be safely made without a chronograph; I did it for many years myself. But When you get tools you quickly see just how mislead you were.

                    And for the record never EVER exceed max data!!!!!!!
                    I agree Andy. I loaded tens of thousands of rounds before I had a chronograph with very few issues and due to the inherent safety element built into modern firearms I did so unscathed. However I'd be very reluctant to go back without one and for the amount of ammo and variety of firearms for which I load, my ammo would suffer greatly.
                    Foolishness is a moral category, not an intellectual one.

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                    • #40
                      I'm wondering if anybody happens to know a web link that shows detailed pics of pressure signs on brass?
                      Sheep hunting...... the pain goes away, but the stupidity remains...!!!

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                      • #41
                        Originally posted by 4merguide View Post
                        I'm wondering if anybody happens to know a web link that shows detailed pics of pressure signs on brass?
                        None that can be definitively correlated to to actual pressures, such that they are meaningful. (Because it can't really be done, which is what several wise individuals here have pointed out; reading brass is not a reliable method of ensuring you're not exceeding safe pressures).
                        ...he who knows nothing is nearer to truth than he whose mind is filled with falsehoods & errors. ~Thomas Jefferson
                        I would rather have a mind opened by wonder than one closed by belief. ~Gerry Spence
                        The last thing Alaska needs is another bigot. ~member Catch It

                        Comment


                        • #42
                          Originally posted by 4merguide View Post
                          I'm wondering if anybody happens to know a web link that shows detailed pics of pressure signs on brass?
                          http://massreloading.com/reading_pressure_signs.html

                          Smitty of the North
                          Walk Slow, and Drink a Lotta Water.
                          Has it ever occurred to you, that Nothing ever occurs to God? Adrien Rodgers.
                          You can't out-give God.

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                          • #43
                            Originally posted by iofthetaiga View Post
                            ^^This is why I don't like to shoot at public ranges. You never know when this guy might be at the bench next to you.
                            I was only saying primers falling out are a example of a case showing pressure, not that I do it. Why do some people have to take every thing literally?

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                            • #44
                              Originally posted by Smitty of the North View Post
                              Thanks much....
                              Sheep hunting...... the pain goes away, but the stupidity remains...!!!

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                              • #45
                                Most all bullets are designed to work best at a certain velocity. I use my chrony for checking to see my bullet speed is within the speed I want it in. I have been loading since early 70's and bought my chrony in late 80's or early 90's. I worked up a load in 7mm Rem Mag with a 140 gr. bullet years ago that has been excellent for deer, and I have shot it in several rifles with good results. I purchased a 7mm STW and tried this bullet and it would not work at all. The bullet would blow up on contact at the speed of the 7mm STW. Also when working up loads I want as little spread as possible in my loads. The more consistent your loads are usually the more accurate they are. I also get a average velocity of my loads to use as a starting point to see where my loads will hit down range.

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