Pressure signs - Nickel Plated Brass?

[j_unzicker]

I have read a lot of threads on nickel vs. brass, but did not find any that addressed any pressure variances. I'm shooting 7RM 168gr Berger VLD, 62gr. IMR4831 (62gr. may not seem too hot for this load, but I am shooting right up against the lands which puts the pressure close to max).
With my nickel plated R&P Brass I am getting slightly cratered primers, but with regular R&P Brass I am not. Does this mean that the harder nickel plated brass can cause higher pressures. Also, my velocity from shot to shot is a little more stable with the regular brass.
Any thoughts on what is going on here?

 

[elkaholic]

I have read a lot of threads on nickel vs. brass, but did not find any that addressed any pressure variances. I'm shooting 7RM 168gr Berger VLD, 62gr. IMR4831 (62gr. may not seem too hot for this load, but I am shooting right up against the lands which puts the pressure close to max).
With my nickel plated R&P Brass I am getting slightly cratered primers, but with regular R&P Brass I am not. Does this mean that the harder nickel plated brass can cause higher pressures. Also, my velocity from shot to shot is a little more stable with the regular brass.
Any thoughts on what is going on here?

I would think the capacity of the case would have more to do with what is going on. Have you compared the two?.....rich

 

[j_unzicker]

No I haven't compared...shouldn't they be about the same? they are same brand. Is there a tool that you use to compare them? What's the proceedure?

 

[elkaholic]

No I haven't compared...shouldn't they be about the same? they are same brand. Is there a tool that you use to compare them? What's the proceedure?

You can simply weigh the brass either with primers in or out and see if they are within a couple of grains, or, the more accurate method, is to weigh the brass empty and record, then fill with water and weigh again. Subtract the empty case from the filled case and that will give you the case capacity in grains of H20. Brass of even the same brand can often be different weights, thus having different capacities. It would make sense that plated brass would have slightly less case capacity than not plated, although, that by itself shouldn't make a significant difference since the plating is so thin. Another possible pressure problem could be excessive case length causing pressure as the bullet leaves the case mouth into the throat. Check you case lengths. Neck thickness can also cause the same pressure problems if excessive, but that is unlikely if it is factory brass in a factory chamber. I am assuming that your pressure difference is occuring when all the other loading variables are the same? i.e. bullet seating depth etc............Rich

 

[j_unzicker]

Thanks, Rich.
I'll try weighing them, but in the end I might just chuck the plated brass. I am concerned about the neck presssure. The thickness of the neck wall is visibly different from case to case. And of course, being plated, I can't anneal them.

 

[elkaholic]

Thanks, Rich.
I'll try weighing them, but in the end I might just chuck the plated brass. I am concerned about the neck presssure. The thickness of the neck wall is visibly different from case to case. And of course, being plated, I can't anneal them.

I recently asked a question about nickel brass and the majority said not to use it because it might flake and damage the barrel so I have decided not to use it at all.......
nickel is harder than stainless!