Noob Question

[CarJunkieLS1]

After you find your window the point of loading in .1-.2 increments is to find the most consistent powder charge velocity wise. Looking for the lowest ES and SD. Once you have that powder charge then you start playing with seating depth to make tiny groups

 

[Metal God]

4. Back away from the maximum charge by 7 to 10 percent, and load one test round with this charge. Add 2% to the charge weight, and load another cartridge with that charge. Load a third test cartridge with the next 2% graduation. You will use these three cartridges for sighters, and more importantly to determine pressure tolerance in your individual rifle.

5. Add another 2% or so to the charge level used in cartridge #3 of step 4, and load three rounds with this charge weight. Add .7% to 1% to this charge, and load three more. Add that same graduation again, and load three more. Continue adding the chosen graduation until you have moved ONE increment above your chosen maximum powder charge.

Can someone tell me what the above means . The wording is confusing me . If my #3 load in step 4 is 43gr what are the loads I now load according to the above quote ??

EDIT

I figured it out and ran the numbers . It became quickly clear that this method completely disregards all charges except charge weights in the upper third of the minimum to maximum caharge range . Really the window is smaller then that if you look at the manuals minimum charge . Its more like only 20% of the potential charges are ever considered .

why is it that it can be assumed you can completely disregard 80% of the potential charges . Why is it assumed the upper 1.4gr of the potential charges are the ones that will give you your OCW . I get that 95% to 100% fill rate is likely best but to disregard everything else seems odd .

I have one load that's actually below Hodgdon minimum by .4gr that shoots lights out in fact that's the first of my pics . Others that are in the mid charge ranges that are very good as well .

I think I need more understanding

 

[CarJunkieLS1]

Bart B. What are your thoughts? I show exactly what I'm talking about with hard evidence and I get (crickets)

 

[Metal God]

I'm going to give the OCW one last honest try . I have some Hornady 168gr BTHP that have not performed as well as I hoped . That was using RL-15 . Fed match primers and LC-12-LR brass . This time I'll use IMR-4895 and see how it goes . It won't be right away , Should be in a couple 2 or 3 weeks . I'll start my own thread when I start the test .

 

[Saintsfan1977]

I figured it out and ran the numbers . It became quickly clear that this method completely disregards all charges except charge weights in the upper third of the minimum to maximum caharge range . Really the window is smaller then that if you look at the manuals minimum charge . Its more like only 20% of the potential charges are ever considered .

why is it that it can be assumed you can completely disregard 80% of the potential charges . Why is it assumed the upper 1.4gr of the potential charges are the ones that will give you your OCW . I get that 95% to 100% fill rate is likely best but to disregard everything else seems odd .

I have one load that's actually below Hodgdon minimum by .4gr that shoots lights out in fact that's the first of my pics . Others that are in the mid charge ranges that are very good as well .

I think I need more understanding

Its not. He explains that in maybe another article? Anyway you should find a node or 2 your gun likes in the upper 50% of the charges. You could possibly get a more accurate charge in the lower 50%. My calculations come to around 50/50 or 60/40 of the charges and not 80/20 but Im guessing it could change.

For example 270wsm using IMR 4350 and Barnes TSX = MIN= 57 ,MAX=63 I think.
So you load 3 rounds starting at around 60-61 gr going up in .5 gr increments until 1% over 63 which is 63.6 Thats over max but remember he says to load 1 round each from min to over max total of around 10 rounds? looking for what your rifle determines is the max charger which could be 62.8 instead of 63. Look for pressure signs.

The reason is if you are loading for a hunting round, and you load for a 7mm RM and you use the lower 50% then you might as well use a .270 or something along those lines. You are cutting alot of velocity down.

 

[Metal God]

Thats over max but remember he says to load 1 round each from min to over max total of around 10 rounds? looking for what your rifle determines is the max charger which could be 62.8 instead of 63. Look for pressure signs.

I don't have the manual in front of me but if I recall the bullet powder combo I'm using has a max load of 43.3 . Reducing 10% gives you a start load of 39gr . Hornady's start load for this combo is 35gr so half is already completely ignored right off the bat . Then you start with the 3 pressure testers which puts you up in the 40.5gr area . then you go up again the increment you have been moving up in the previous 3 loads and start the "real" group testing . Your actual groups that you will be testing start around 41gr or so . leaving a total of 2.3gr of charges to work with . Not the the 8.3gr of charges you could be using . Maybe not 20% but closer to 20% the 50%

This is assuming I did calculate the charges correctly