Sr 4759

[cbrick]

The bad thing is that changing one thing at a time might not get results.

But if multiple things are changed in one test and the results are better, worse or the same which of the changes are the cause? If only one thing is changed for a given test and the results are better, worse or the same you know the result of that change.

Rick

[44man]

But if multiple things are changed in one test and the results are better, worse or the same which of the changes are the cause? If only one thing is changed for a given test and the results are better, worse or the same you know the result of that change.

Rick

That is what makes things hard. If a primer is causing the problem, changing the lube will do nothing and the alloy change will not show enough either.
Change the primer with a poor alloy and back to square one.
You really need a very accurate, proven load first. Then change something and work loads around it.
So how is the first accurate load found?
Over the years I have found what does not work and have eliminated those things, never to go back to them. It took time.
Soon with enough experience, you can read a target and tell what is wrong. But if everything is wrong at the start, it is back to

[cuzinbruce]

You might want to check the gun over, bedding, everything tight, scope mounts and scope (if any) and so forth.

[XWrench3]

You have received a bunch of good info. 4759 is not touchy unless it is downloaded too much. It can fail to ignite even with Dacron.

fail to ignite, hang fires, lots of unburnt kernels. all are possible with to light of a load with it. but if the load is high enough to burn properly, i have not had a position problem either. i have tried Dacron filler, but my experience was better without it, than with it. try varying the load a few grains, one at a time, each way.

[bullshot]

Update. I loaded 10 rnds each of 23,24,25,26 gr 4759 behind the RCBS 300 CSA boolit sized .409 and lubed with 50/50 seated to crimp groove with a light crimp. Nothing changed in the loading except the crimp. 23 gr shot into 1 1/2 in at 100 yds. I was happy , thinking the crimp was a plus. The following three charges degraded as the charge went up. I checked my notes from previous attempts and the groups did degrade the same as the charge went up. When I say degrade it's with multiple fliers and progressively worse. Going to try reducing the charge and see what happens.