An experiment-Reading Primers - with a friends rifle

[cloverleaf]

I have had my share of issues, including broken rifle parts recently, and while things are looking up, I was looking at the fired reloads from my friends model 99 in 250- 3000 Savage and I noticed what looked to me to be "cratering" of the fired primers. Given my recent experiences I decided to be EXTRA careful and do a ladder test *(at least thats whet I'd call it) to see if there were changes in how the primers look. Speers load data for this 87 Gr. bullet, in IMR 4350, 250 Savage runs from 37 to 41c Grains. My initial reload for this rifle was 39.5 Gr. All loads tested fired w/o any notable indications of "sticky bolt". My load of 39.5 gr was as hot as I went. None of the loads on my " test" went any higher than that unless you count the 100 Gr factory loads (also in the pics).

So, the photo starts with Rem. 100 gr Factory loads (Sorry- red sharpie on these primers). The next load was 39.5 gr. Subsequent 2 round "groups" were reduced by 1/2 grain increments down to 37.5 gr. The results are pictured below.

Again, this is just a visual assessment of fired primers . From what I see, I will stick with my 39.5 Gr load. I am assuming the "cratering" I see is either "normal" or the function of a large primer hole in the bolt face.

The target dosent really mean any thing, I wasnt working really hard for groups.... more shooting of a 38 gr load might be worth while. 39.5 Gr is accurate enough.

Any thoughts, observations- just posting for the sake of conversation. CL

 

[RL338]

I am assuming the "cratering" I see is either "normal" or the function of a large primer hole in the bolt face.

Excessive firing pin clearance will show cratering like you’re seeing. If the 39.5gr is to your liking then there is no need to push higher.
I have several rifles that the firing pin was turned down and the bolt face bushed to eliminate the cratering issue.

 

[JD338]

What Rick said

JD338

 

[SJB358]

What Rick said

JD338

Yup, what Rick said. Firing pin holes that are a bit bigger will give cratering across the board. In my world, they aren't a great indicator of much other than machining.

Your friends 250 is pretty slick. Very nice rifle

 

[cloverleaf]

Thanks Guys- Little extra firing pin clearance in the bolt. Kinda what I figured. I get acceptable accuracy at 39.5 gr. so unless things change I will stay there. I have heard of shimming a firing pin, but I'm not sure its the best plan for a 100 year old rifle and my friends budget. If money was no object, I could send it to Mr. Turnbull, now that would be interesting......

My take away- cratered primers - yup thats what they look like- can be an indicator of over pressure, but not the only one, or always the cause. CL