Load development ?

[340Shooter]

Please clarify... I'm in no way new to reloading, but I am new to bushing dies . I thought bushing size was how you changed neck tension, and how does .000" change anything?

Yeah, I am confused too. I thought changing bushing size did change neck tension. Isn't that the idea...

 

[joe0121]

I didn't buy a Krieger #10 contour to worry about hot bore stringing shots.

I use the OCW method so the first round is all cold bore. I clean the bore after round 1 then fire three cool for 45-60 seconds fire three and so on. this keeps the bore pretty warm but not super hot. This will give me an idea of where my cold bore shots will be vs warm bore. Also it opens up the groups and exaggerates the OCW and scatter node. I also plan on shoot F-class type matches so I will have a good idea how the rifle behaves when hot. It also give me an oppertunity to work on shooting through mirage.

 

[Mikecr]

Neck tension amounts only to springback area gripping a bullet, and brass only springs back maximum that it can.
Your properly determined bushing size accounts for springback and brass thickness to provide DESIRED tension. Beyond max tension, as dependent on your brass hardness, you're only oversizing necks, which is bad.
When the bushing isn't small enough, the necks can spring back to leave little or no tension(.000").
Annealing is another subject, but directly affects tension(always reducing it), as it affects springback. Sometimes this is just what the doctor orders.

To see what your actual tension is, size a neck, seat a bullet, measure the loaded neck OD, pull the bullet, measure the neck OD. That springback amount(and only that) is what grips the bullet.

 

[bowhunthard88]

Neck tension amounts only to springback area gripping a bullet, and brass only springs back maximum that it can.
Your properly determined bushing size accounts for springback and brass thickness to provide DESIRED tension. Beyond max tension, as dependent on your brass hardness, you're only oversizing necks, which is bad.
When the bushing isn't small enough, the necks can spring back to leave little or no tension(.000").
Annealing is another subject, but directly affects tension(always reducing it), as it affects springback. Sometimes this is just what the doctor orders.

To see what your actual tension is, size a neck, seat a bullet, measure the loaded neck OD, pull the bullet, measure the neck OD. That springback amount(and only that) is what grips the bullet.

Thanks for clarification! Understandable, that was my view before. Bushings do provide different neck tensions up to an optimal point.

 

[Dr. Vette]

I didn't buy a Krieger #10 contour to worry about hot bore stringing shots.

I use the OCW method so the first round is all cold bore. I clean the bore after round 1 then fire three cool for 45-60 seconds fire three and so on. this keeps the bore pretty warm but not super hot. This will give me an idea of where my cold bore shots will be vs warm bore. Also it opens up the groups and exaggerates the OCW and scatter node. I also plan on shoot F-class type matches so I will have a good idea how the rifle behaves when hot. It also give me an opportunity to work on shooting through mirage.

So which of these loads did you like, and what was your next step in development?
I'm about to start an OCW series for the first time and know what I'd pick but wondered what you chose.

 

[joe0121]

So which of these loads did you like, and what was your next step in development?
I'm about to start an OCW series for the first time and know what I'd pick but wondered what you chose.

I chose 79.5 gr. Looks like another node at 81.5 ish but I just cant get that much in the case. Next I will adjust seating depth in .008 increments from .020 off the lands to .012 in the lands.

This target was shot with a wicked mirage and a "boiling" wind.

BTW I own a 99 Vette with some mods for a couple years. Really miss it. Saving for a C6z on day.

 

[Dr. Vette]

I chose 79.5 gr. Looks like another node at 81.5 ish but I just cant get that much in the case. Next I will adjust seating depth in .008 increments from .020 off the lands to .012 in the lands.

This target was shot with a wicked mirage and a "boiling" wind.

BTW I own a 99 Vette with some mods for a couple years. Really miss it. Saving for a C6z on day.

OK.

My thought was to try a few from 79 to 80.5 and see what you got if you felt like going further - again, based on reading about this a lot and not having yet tried it.

Bought an 08 for my 40th birthday a few years ago. Nice cars.

 

[joe0121]

OK.

My thought was to try a few from 79 to 80.5 and see what you got if you felt like going further - again, based on reading about this a lot and not having yet tried it.

Bought an 08 for my 40th birthday a few years ago. Nice cars.

IMO once you find the powder charge range fine tuning is better served with seating depth changes.

Not sure how well read you are on the process but the idea is to tune a load so the bullet exits a bore as the initial shock wave is closer to the action. The theory is when you light off the round a shock wave travels up and down the bore distorting it ever so slightly. If this wave is at the bore at the time the bullet exits it will throw the impact off.

 

[Mikecr]

Joe you might notice that seating depth adjustments hold the very largest affects to grouping, and without evidence that it relates to tuning nodes at all. In fact, you can't tune into nodes any more with bullets, than primers. These only set size and shape of groups, tuned or not.
Powder is an actual tuning adjustment, as it can be taken right to the kernel, and you can easily tune into and out of nodes with powder.

You can also find best seating with any load, tuned or not.
So seating depth should be prerequisite to tuning, leaving best grouping easier to see(as it would be closer to actual).
When you tune first, you're interpreting grouping by size and shape -that will change with later seating adjustments. So afterwards you would only know if you chose the right size & shape by running incremental powder changes again(starting over).
It's a backwards tail chasing.

In other words, those target groupings will look different once at optimum seating, so how can you really guess which is best before so?
IMO, you can't.
Pick any load there, and adjust seating to shape that load from squares to triangles to bunny rabbits.. You can pick any other load & do the same thing. Then your target choices could be completely different!

I think this is why reloaders end up with such horrible ladders. Their randomly chosen/assumed seating has invalidated the testing.