2 reloading questions

[Deleted old_dood]

my equipment: Forster Coax press, Redding Type S FL die, 6mmbr Lapua brass from the same box.

1. I get a variation of up to .002" on various cases headspace measurement when using the Hornady set for measuring same. Why would this happen and should I be concerned? The press is set to very lightly cam over.

2. Is the best OAL for a particular bullet/load a constant? If I change powder or load would the best OAL for that bullet remain the same?

 

[johara1]

Anneal the brass first, dwell time when sizing ….. pull the handle down and put wax on the next case . If you slow down it will be better and if you anneal it will be even better……… jim

 

[Alex Wheeler]

Listen to Jim. Redding competition shell holders also made all the difference in the world to me.

 

[Deleted old_dood]

I had just annealed 100 cases from that box. On the cases that didn't bump enough, I pushed the arm down, applied more than the usual force and held it there a moment. It didn't make any difference. So I adjusted the die down which now results in certain cases being bumped more than I would like, in the neighborhood of .004" a Problem? I'd rather not have to modify a nearly new press so I can revert back to using shell holders which the Forster doesn't use.

 

[Dos XX]

Is it possible that some are several thou shorter than others when you start? Have you measured them with a comparator before you size them? In other words, could the die be touching some and not others? Also, if the die isn't touching the shoulder, it will sometimes push them out, actually lengthening the dimension.

 

[BCoates]

Like said above, check to see if your brass is all starting out at the same headspace. If you have to size some cases more than others there are going to be differences in the amount of springback. Also, try to maintain consistency in your press stroke. Lastly, an possibly most important, make sure you are lubing the cases the same amount. I use imperial wax, and I know if I put too much on one case it will cause the shoulder to be bumped back more and then next case or two after that will be bumped back more because there is lube buildup in the die. My case sizing is still not as consistent as I would like it to be, but it has gotten better since I changed from spray lubes to imperial wax because I can control the amount on each case much better.

 

[Deleted old_dood]

thanks, will try all suggestions. does anyone have any thoughts on the second part of my query?

 

[pastime]

I believe that OAL is firearm specific and has more to do with variations in chamber size for each individual firearm. There is usually a SAMMI minimum and or maximum OAL in the load data for any given load and if you stay within those limits and the cartridge will fit in the magazine and cycle through the firearm you should be good to go. The SAMMI maximum and minimum OAL will vary with different bullets and different powders and of course different calibers. If you exceed the listed SAMMI maximum and minimum OAL then you may run into pressure issues. Someone may chime in to correct me but this is my understanding.

 

[Dos XX]

Interesting question. I just changed powder on my .308 F/TR gun. I ended up with the same velocity and the same jump as my old powder. This after going through the node test and a seating depth test. Seemed like I could have saved some components and time by just finding the velocity and jump of my old load. I don't know that it always works that way.

 

[Deleted old_dood]

2. Is the best OAL for a particular bullet/load a constant? If I change powder or load would the best OAL for that bullet remain the same?

it looks like I wasn't specific enough. I should have said "in the same rifle". for example, if the best accuracy is at .024 jump with one powder, will the best accuracy occur in the same rifle, with the same jump, with any powder?