I have worked up 5.56 loads for my ar15 with H335 at 24.5 gn and cci 400 primers. I came across some #41 primers, which are a magnum primer, and I'm wondering how far back I should cut charge back with the magnum primer
Yeah man reduce down to starting charge or by 10%, whichever comes first. You can work back up but only load like 5-10 not 100 so you don’t waste components. I use 400 and 41 a lot with 55 gr pills and the 41 are definitely hotter. Being that close to what I’d call max for your rifle I’d go super conservative on this one. I’d recommend if funds are available getting a chrono, you don’t need a fancy one. I grew frustrated working up a load with 55 fmj and h335. I started super low and wasted a lot of components. Got to the point where a given increase in charge gave me predictable Increase in velocity. Until it didn’t. When you get closer to max, all that goes out the window completely. Anecdotal: 0.2 gr increments gave me almost exactly 50 fps increases for 1.6 gr span. Til I got near max and it went 150! , over pressure, blew primer, locked up FCG. The difference between 41 and 400 is greater than that difference. Don’t be me, learn from my mistakes.
Are we talking a 55 gr pill? Is yours a 556 chamber? Who made the barrel? Do you have A chrono? If that load flattened a 400, I’d reduce by 10% when switching primers since we’ll call this a max load for your gun. Then work back up. Don’t load 100, maybe 10 and test again. You can always work back up and don’t need to waste a bunch of components. You or the gun may not get the chance to work back down, if you catch my drift.
Yeah man reduce down to starting charge or by 10%, whichever comes first. You can work back up but only load like 5-10 not 100 so you don’t waste components. I use 400 and 41 a lot with 55 gr pills and the 41 are definitely hotter. Being that close to what I’d call max for your rifle I’d go super conservative on this one. I’d recommend if funds are available getting a chrono, you don’t need a fancy one. I grew frustrated working up a load with 55 fmj and h335. I started super low and wasted a lot of components. Got to the point where a given increase in charge gave me predictable Increase in velocity. Until it didn’t. When you get closer to max, all that goes out the window completely. Anecdotal: 0.2 gr increments gave me almost exactly 50 fps increases for 1.6 gr span. Til I got near max and it went 150! , over pressure, blew primer, locked up FCG. The difference between 41 and 400 is greater than that difference. Don’t be me, learn from my mistakes.
Yes, 55 pill and 5.56 chamber
Are we talking a 55 gr pill? Is yours a 556 chamber? Who made the barrel? Do you have A chrono? If that load flattened a 400, I’d reduce by 10% when switching primers since we’ll call this a max load for your gun. Then work back up. Don’t load 100, maybe 10 and test again. You can always work back up and don’t need to waste a bunch of components. You or the gun may not get the chance to work back down, if you catch my drift.
Getting close to max load. No pressure signs except the fired primers where flattened
What chamber? Did you work up to 24.5 and stop? Had you gone higher with no pressure signs but settled on 24.5 for accuracy?