Primer Seating Data for Extreme Long Range

[jdmecomber]

Hey Shooters,

I wanted to do some research on primer seating or methods you shooters are taking to obtain your best standard deviations/extreme spreads for precision long range. Does anyone have any good articles, data or research on this?

 

[Clearlight]

A quick google search revealed a few books on primers for BR shooting .
Plenty of good practises from BR carry over to ELR . Getting your ES down
to sub 10 fps is one of the most critical issues .

 

[jdmecomber]

A quick google search revealed a few books on primers for BR shooting .
Plenty of good practises from BR carry over to ELR . Getting your ES down
to sub 10 fps is one of the most critical issues .

Thanks for the heads up. I will check it out

 

[Canadian Bushman]

I have been experimenting with primer seating depth, or crush.

Im not certain, but i think im seeing a trend between a slight crush and lower S.D. Certainly noticing a trend between more consistent accuracy when primer seating is monitored closely.

A member here, MikeCR use to swear that final tuning with primer seating "crush" and firing pin force was absolutely necessary for winning BR level accuracy. I think he believed .003-.005" crush was optimal for most primers.

Dont know if he messes around on the forums much anymore. If you can catch him with a PM im sure he would have an interesting view.

 

[jdmecomber]

I have been experimenting with primer seating depth, or crush.

Im not certain, but i think im seeing a trend between a slight crush and lower S.D. Certainly noticing a trend between more consistent accuracy when primer seating is monitored closely.

A member here, MikeCR use to swear that final tuning with primer seating "crush" and firing pin force was absolutely necessary for winning BR level accuracy. I think he believed .003-.005" crush was optimal for most primers.

Dont know if he messes around on the forums much anymore. If you can catch him with a PM im sure he would have an interesting view.[/


It's seems this learning process never ends. Thanks for the info

 

[jdmecomber]

It seems this learning process never ends, thanks for the information.

 

[steeltraps]

Primer pocket reamer use. Has given me lower ES spread in the past. Usually LApua is very close, but I want ALL my primer pockets to be same depth. May only have 4-5 out of 100 peices of Lapua brass that need primer pockets reamer = uniformed .But I want them all to be 100%

 

[Chad Schmidt]

Another benchrest practice is to clean/deburr the internal flash hole it is the logical step for consistent ignition.
Chad

 

[just country]

morning on the subject primer flash holes and pockets. I have
had to realm the flash hole on several lots of weatherby brass.
any answers?? justme gbot tum

 

[ar10ar15man]

uniformity
all primer pockets the same depth
all primers seated to the bottom of the pocket and then a small crush in place..aprox .002
all the small things add up.
yes i WEIGH MY PRIMERS.

 

[Chad Schmidt]

morning on the subject primer flash holes and pockets. I have
had to realm the flash hole on several lots of weatherby brass.
any answers?? justme gbot tum

Most flash holes are punched in not drilled so the size, shape and even placement can vary. Inside the burr can be evenly spaced around the hole or protrude mostly on one side. Most internal rebutting tools have a pilot that is a small center drill to uniform the flash hole while removing the burrs and putting a slight bevel on the inside of the flash hole. Careful not to go overboard on the bevel as it will make the flash hole thin on the primer pocket side.

 

[Chad Schmidt]

Weighing primers: what variation is acceptable & what accuracy is the scale you use?

 

[TK50]

If you want to get everything you can from your long range setup you need to weigh primers. Get a lab scale that reads to at least two decimal places and will hold 2 hundredths of a grain accuracy. Do you need all of that or can you make use of it all would be a better question. I don't know for sure but it is better to have it so you can have as little variance in the final weight as far as scale accuracy as possible. Then you sort at least 300 to 500 primers at a time and batch them as close to the same weights as possible. I have done this for at least 20 plus years for my 1000 yard Benchrest ammo and also for my long range hunting ammo. You can definitely see the difference in group size if you have a gun that shoots accurately enough.

 

[Alex Wheeler]

Its still common practice to seat primers by feel in Benchrest. If you could be sure the extractor groove and primer pocket depths were exactly the same case to case you could use a tool with a set depth for a certain crush. If your serious, you could take the measurements and come up with the numbers and measure the depths to be sure you got the crush. Lots of work, but thats the kind of stuff you do to win.