Brass Experimentation Question

[Ledd Slinger]

Doesn't 6PPC brass come with a 0.060" dia. flash hole? I hear it's the most popular cartridge amongst BR shooters out to 200 yards? I don't shoot BR so I can't say I have first-hand knowledge, but I know a bunch of folks shooting 6BR's & Dashers than use 0.063" so there's something goin' on with a little hole in cartridges known for accuracy.

Few years back I bought a case of Speer 45ACP loaded with 180 gr JHP ('flying saucer' I think that bullet was nicknamed? They stopped making it since.) About 20% of those cases had flash holes that weren't much smaller than the primer pocket... but on paper shot just the same as the 0.080"-hole brass that came in the same boxes.

Thanks for sharing that experience.

 

[Ledd Slinger]

Another reason this piqued my interest is because primer changes can sometimes dramatically effect the accuracy and grouping characteristics of a load. As most know, different brands of primers have different blast shapes and sizes. Some give more powerful blasts than other's when thinking about standard vs magnum, but at the same time, Federal standard and magnum primers do not give the same blast pattern and power as CCI, Winchester, or Remington. The various brands blasting traits undoubtedly can change the characteristics of a load on paper. Of course blast trait 'consistency' of the primers play a major role in this effect as well. But when a person changes the size of a flash hole, common sense would say that you are changing the blast characteristics on the powder charge as well.

This is all just food for thought. I'm not thinking this will be the next greatest practice in load development. Just interesting to me. Over the years I have tried and done just about everything, so I get excited when I find new possibilities to expand my knowledge on the art of hand loading.

 

[BillPa]

Another reason this piqued my interest is because primer changes can sometimes dramatically effect the accuracy and grouping characteristics of a load.

Sure. There isn't a standard what primer will always produce the best results in a given combination of components for a given cartridge.
For example, I use a F210 w/a healthy dose of R22 for my 280Imp, a F215 for my 250Imp w/RL15. The 260, a F210 w/H4350 and a BR2 or 200 w/4451. Why? Because those primers produce the best results in those combinations. I have no way of knowing how a primer ignites the powder so all I can go by are the targets and clock info.
In my feeble old mind trying different primers is just another part of the tune the same as tweaking seating depths, charge weights and etc.
Bill

 

[Ledd Slinger]

Sure. There isn't a standard what primer will always produce the best results in a given combination of components for a given cartridge.
For example, I use a F210 w/a healthy dose of R22 for my 280Imp, a F215 for my 250Imp w/RL15. The 260, a F210 w/H4350 and a BR2 or 200 w/4451. Why? Because those primers produce the best results in those combinations. I have no way of knowing how a primer ignites the powder so all I can go by are the targets and clock info.
In my feeble old mind trying different primers is just another part of the tune the same as tweaking seating depths, charge weights and etc.
Bill

I do the same. During load development, I will find the powder types and charge levels that give the best results with a given primer at 100 yards, usually start with Fedreal in all the loads. Then I will take the best loads and try them with various primers. Various CCIs, Remingtons, and other types of Federal - match and standard blue box. I take the best combos from that testing phase and shoot them at 300 yards. Then I take the best 300 yard performers and start playing with powder charges in .1 or .2 gr increments. At this point I am looking for forgiveness in powder charge levels up and down. Finally, I take the best of those groups and start adjusting neck tension and seating depth until I acquire an acceptable level of accuracy and consistency for the intended use of the rifle. Many times I achieve acceptable accuracy before I ever play with seating depth or neck tension. My normal starting point for neck tension is .004" and seating depth is within .010" of the lands or maximum seating depth for the magazine allowance, which can vary greatly from rifle to rifle if a custom designed reamer is not used.

 

[Shaggy357]

Primers have a variable burn rate the same as powders. The primers are designed to that rate based upon the "standard" flash hole size. (Something had to be "standard".) The primer ignition is controlled by the size of the flash hole. The smaller the hole, the slower the burn, but hotter pointier flame as the gasses escape the primer pocket. The larger the hole, the faster the burn, and cooler fatter flame escapes the primer pocket.

Years ago the gallery and wax bullets were fired with a primer only. The flash hole was opened way up to allow the fast fat flame to launch the bullet. The "standard" flash hole, with hotter and pointier flame would act like a torch and melt the base of the wax and plastic bullets. This limited their life. (I still have some Speer gallery loads at home.)

A buddy of mine got some of the Lapua 6br brass for an XP. We could not understand why his loads were so much slower than ours and why the barrel was so dirty. We had been shooting these for years..... Come to find out when he got the new brass, the first time into the sizer die he stuck a decapping pin. He took the 100 cases out to the garage and opened up the flash hole so his "standard" decapping pin would work. Fast fat flame pushed the bullet out the barrel before the powder could all burn. Our smaller flash holes allowed that hotter pointier flame to continue to burn the powder, even after the bullet was in the barrel. More powder burned = more velocity. He had to go to a magnum primer to get some of the performance back.

Off center primer hole is going to direct that flame off center within the case. Full case of powder, likely you will never notice. Partial case of powder could have flame directed away from where powder lays creating variation in burn rate. Variation in burn rate = variation in velocity = variation in group size.

Load to near case capacity and I doubt you could ever pick one off center flash hole from a group of 10 shots...even to great distances.....

My version of the story.....

Steve