Primers are Primers, Right?

[mapper]

i thought the part about the delayed ignition at starting loads as well as using pistol primers for 22 hornet was interesting in that article.

this is some pressure trace data from another forum i frequent, it is a bit long, but interesting.

Here is some primer data for you guys to look at.

I have been struggling with flyers from more than one rifle and I'm trying to find the cause.
90% of the time I load with 450 primers for all of my small case cartridges. I have a few different loads that don't use 450's for whatever reason.

The data was collected from the 20" McGowan 6mm Mongoose barrel. I used a different powder and target velocity to insure that the Fiocchi and 6-1/2 primers wouldn't pierce. They are softer than the rest that I tested.
TAC has also been unusually inaccurate from this barrel, so I might as well look at it as well.
I only have 5 different small rifle primers on hand. I will be getting some more varieties to add to the test results from today.


Load data
Case- TA-10 neck turned flash holes de-burred
Primer- varoius
Bullet- 55gr. Nosler shots
Trim- 1.690"
Powder- TAC
Powder Charge- 29.0gr.
Barrel- 20" 4groove 8T McGowan AR
COL- 2.100" 1.805"
Temp- 80*

First is the target. It looks like the Remington 6-1/2 is giving the best group with the others looking mostly the same at around MOA. the grids are .9"




I think the dip in the graph before the barrel exit is the cause of some of my accuracy issues. This is a characteristic of TAC powder with the 20" Mongoose barrel. A different length barrel might like it better than this one. The delayed ignition on some of the primers is not helping either.

Here are the traces.


The Rem 6-1/2's don't look too bad compared to some of the others. At this pressure level they are safe. I wouldn't want to go up much more with them. They had some light cratering.


These 450's are dog doo-doo just the same as the BR-4's. Delayed ignition on some shots.


The BR-4's that I have are dog doo-doo for the Mongoose. Look at the delayed ignition at the front of the chart. These same batch of primers are what I use for my 6.8SPC long range loads. That rifle shoots sub .5 MOA with es in the single digits with these same primers.



The Fiocchi is the best looking of all of them. Velocity was higher, ES in the teens SD in the single digits. I'm going to be hunting for some more of these. Too bad they cant stand much pressure. Will have to limit them to less than 60KPSI to prevent piercing. I can live with that...



This the WSR chart. I only got 3 shots recorded because I forgot to turn stuff on.
Looks like dog doo-doo anyways...

[Jafar]

i thought the part about the delayed ignition at starting loads as well as using pistol primers for 22 hornet was interesting in that article.

this is some pressure trace data from another forum i frequent, it is a bit long, but interesting.

As did I. I wonder if those cases and the one in the graph left unburnt powder in the chamber.... Remember that .204 I was telling you about?