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I am using 64 grains of IMR 4350 and soft woodleight bullets for my little Chapuis. Any advice on changing from Large Rifle to Magnum primers?? I will use 215 Federal. Anyone has a load with magnum primers for the 9.3 x 74R that works well. Thanks, |
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In the Woodleigh manual they state: "Standard force primers are recommended for ignition." YMMV. |
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Seen those in a couple manuals. Unfortunately I don't have them!! here in the tropics it may take 3 months before the army releases my ammo imports. |
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Shouldn't make a huge difference. Would be wise to drop a couple of grains and then work up but I think you'll end up at the same load. I've had to go to magnum primers in the past for various cartridges and I've ended up with the same loads. The magnum primer is supposed to give a longer duration hotter flame and not necessarily increases pressure but it is safest to drop back and work up. |
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DDouble, if you are right at the top load for your 9.3x74 drop 3 gns of powder before changing over to a magnum primer. It is a pain in the bum to redo all your loads again, but it will get you by! I tried with my 9.3x64mm to see if it would improve grouping & it uses AR2209, (very similar to IMR4350) only standard primers were required to set of the charge! After a load of testing frankly it didn't achieve better grouping, just marginally less powder was used in my rifle so I reverted back to my 'standard' load! Don't be put off, it may be a better load than you already have - but watch for pressure signs as normal practice |
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The debate over wether Magnum primers have any effect ( good or bad) over standard in " Standard" cartridges is a long one. In my experience the difference is not perceivable . They are of course recommended for long columns of the slower powders. Whenever you change a component, start low and work back up, but I doubt you see any difference at all. Best |
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Thanks to all! Very good advice. And it seems all answers above were very consistent with other good sources I found. In addition to 4350 I will be using CBC 126 (which is a Magtech powder) and it is perhaps a bit slower than 4350. Will take the advice to lower the charge and see where I get convergence while looking for precision and pressure signals. Thanks again! |
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63.5 grains of IMR 4350 with a 286 grain bullet and standard primer shot extremely well in my Chapuis (2 pair L&R into 3/4” at 50 yards) but were crossing. I’m unconvinced that magnum primers are needed for this and the 375 H&H. |
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If groups are round and as tight as you need - there is no need for magnum primers with THAT powder and charge/bullet. I would also add to that, that there is normal spread, shot to shot on the velocities. |