Flattened primers?

IronCanadian

IronCanadian

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I took my new M96 Swedish Mauser to the range today with some handloads I put together Wednesday.

During the shooting of these rounds I did NOT notice any indication of over pressure; stiff bolt, heavy recoil or abnormalities with the cases and the chrony did not show any abnormally high velocities.

After getting home I took a closer look at the rounds and noticed something with the primers that looked off to me, but I have limited experience reloading so I come asking for advice. To me the primers all look flattened and some are cratered, I think.

Here is a picture of the cases, from left to right, 35gr to 38gr in .5g increments. Sorry about the picture quality, it's the best my crappy camera can do.

http://i866.photobucket.com/albums/ab229/choicesolutions1/IMG_1215_zps06c82773.jpg~original

The powder charge information comes from the Lee 2nd edition:

Powder: IMR-4064
Charge: MIN 35 - MAX 38
Primers: CCI-200
Bullet: Hornady 140gr SP
Brass: new PRVI
OAL: 3.050"

Below are the chrony readings (the readings do not match to any case order):

35.0 - 2353,2407,2428
35.5 - 2434,2488,2434
36.0 - 2507,2436,2439 (top primer looks cratered)
36.5 - 2500,2510,2507 (top and bottom look cratered)
37.0 - 2513,2554,2529
37.5 - 2596,2571,2543
38.0 - 2548,2555,2575

Your expertise is appreciated.
 
I don't consider myself an expert but that defiantly looks like mild overpressure to me.

remember that different chambers generate different pressures regardless of the load, could be your rifle has a particularly tight chamber.
 
Last edited:
Well yeah, 6.5mm with the heavier 139-142gr generally like/need a slower powder like H4831, N160. I find even H4350 too fast unless they're 123's.
 
You are wise to double check. I saw a Husky 6.5 that blew the primer big time with a START load. Those 140 gr bullets have a long bearing surface and a tight throat can boost pressures quickly. Your velocities look about right. 37gr should work just fine, based on velocity.

By using a fast powder you are making the situation even more tricky. RL22 or 4831 would be better suited.
 
To me, those primers look like they should after firing. Somewhat flat but still with rounded edges. As for the gratering, probably a slightly over-size firing pin hole.

Neither are something to worry about.
 
Mauser98 said:
To me, those primers look like they should after firing. Somewhat flat but still with rounded edges. As for the gratering, probably a slightly over-size firing pin hole.

Neither are something to worry about.
Click to expand...

That is what I thought but the photos lacked closeup clarity and I didn't want to clean my computer screen and still guess. :rolleyes:
 
Just looking at the chrony results i would say that 37g is your load. how was accuracy?
your primers will flatten a bit anyway but I dont see anything untoward here.
Any one else?
 
Thanks for the information and powder recommendations Ganderite, I'll try RL-22 on my next loading.

Mauser and Snoopy, the primers didn't completely fill the pocket and are still a bit rounded. As for accuracy, the groups were nothing spectacular, all were within a 6" target. The best was 35gr @ 2" and 37gr was 4".

I wouldn't call it a fair grouping though, I was finding it difficult to get in a shooting rhythm with the sights on the rifle.

Still trying to get a better closeup of the primers for you Ed.

Thank you all for providing your thoughts on this.

BTW - any recommendations for checking if I am dealing with a tight chamber?
 
overpressure loads will usually have a very difficult bolt lift before primers flatten hard on a rifle. the pressure spike is not quick enough.
i have seen primers that have become part of the case they are so flat. but on pistols only.
what i see here is diminishing returns for the amount of powder added based on what you are telling us. 2500fps is what she will give you so use the load with the least amount of powder that achieves that.
if the action cycles without issue, you have no problem.
shoot it for accuracy from that point.
my .02 less the current exchange rate.
 
Flattened primers only means you reached X pressure to flatten that brand of primer. Federal primers for example flatten well below the maximum pressure of many cartridges. Likewise CCI primers wont flatten even when dangerously over pressure on other cartridges (generally older cartridges like 45-70).

I've had factory Federal .300WM ammo flatten and crater the primers while delivering normal velocity.
I've also had factory Hornady .300WM ammo really stick my bolt and need to be tapped with a piece of wood to open (my guess on that one though is overly soft brass).
 
The clearance around the firing pin in the bolt face can sometimes allow softer primers to "flow" into the hole. Look at your primers and compare them to this hardly noticeable flowing below, and it was not caused by high pressure.

DSCN6037_zpsa0f66638.jpg
 
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