I am working on loads for my 280 remington, and have primers flattend or bulging back with my starting loads(well below maximums). I don't have any other signs of high pressure (hard extraction, shoulder dents, or extractor marks), but haven't mic'd to check actual case expansion at the pressure ring.

Does anyone have any thoughts as to cause/solutions for this issue? The gun is a custom mauser (Argentine 1909 action) with a 24 inch pipe. I was hoping to work up to a 140 grain bullet between 2900 and 3000 fps, which shouldn't be asking to much for this cartridge.

Thanks
Jasper243

You might have headspace issues. Here is what can happen. The firing pin drives the case foreward. The pressure of the primer firing backs it out of the case. The pressure of the main charge drives the whole case back and reseats the primer. This can make it look flattened with a low pressure load.

As the previous poster suggests, you have described the classic signs of slighty excessive headspace (which is more accurately described as the cases being slightly too short in the base-to-shoulder dimension to fit the chamber snugly).

The "cure" is to only resize the fired case enough for it to re-enter the chamber and have a snug fit against the chamber's shoulder walls, thus holding it firmly against the bolt face and leaving no opportunity for the firing pin to drive it forward. If you persist in full-length resizing for this chamber, you will soon (three firings or so) develop a case head separation at the point where the web transitions to the case wall, about a quarter inch in front of the rim.

In my book, there is no such thing as excessive headspace, only cases which do not fit the chamber properly. Of course, this is from the perspective of a life-long reloader who tailors his loads for each individual rifle.

These guys have it exactly right. You have no pressure problems to worry about at all. Alot of people get exited at this exact problem just as you did thinking they've made alot of pressure and they haven't.

Thanks a million guys...

Stonecreek- Would neck sizing only be a good answer to this problem? If not, how do you suggest that I start the process of partial re-sizing to determine how much I need?

Jasper243

Maybe I shouldn't answer because I'm not Stonecreek but here's how it can be done. Leave about a dimes thickness space between the bottom of you die and the top of the shellholder. Size some brass and see if they chamber nicely. I'm guessing they probably wont. At this point keep turning your die approx 1/4 turn down until they start chambering. This is the point where you are very close to making the shoulder dimension equal to your chamber. Some people call it "bumping the shoulder back" which some people argue is or isn't happening. But the bottom line is you need to find a height where your dies make the chambering snug and then back the die down just slightly (maybe 1/32 turn more)for ez chambering out in the field. If you ever get really serious about reloading get the stoney point universal headspace kit. You get 5 bushings that cover most any caliber for about $35 and it really really is a neat and useful tool especially if you reload for quite a few calibers (or friends which starts a whole bunch more arguments here). I hope I've made this understandable. Just in case you are interested, below I've pasted how to "tune" your expander spindle for concetricity--it's from another post if you like it good, If not sorry I put so much out!!!

My $.02 worth---ALL dies with expander balls need tuning. Think about it...a piece of typing paper is .003" thick--what are the odds that the expander is not PERFECTLY centered in a die??? Pretty good I'd say. Pull the expander stem out of the die (and now is a good time to clean the inside of the die). Run about 5 brass into the die and see if they come out concentric. If they do (and usually they will) you now have to try and get that stem centered on re-assembly. A great way that helps is to put a piece of very concentric brass up into the die to hold the stem in place as you tighten it down. Sometimes this takes 2 people unless you have 3 or 4 hands. AFter reassembly try sizing some brass and check runnout. If not good then do very small turns of the expander stem--probably 1/32 of a turn at a time. Resize some brass and repeat the small turns. At some point I can almost guarantee that you will get GREAT RUNNOUT CONSISTANTLY. (Somehow, someway the expander spindle will hit almost perfect centering in the die body) I have many dies that consistantly make less than .002" runnout after sizing with most of the brass at .001" and less. I own, hornady, redding, forester, rcbs, and lee dies. ALL OF THEM HAVE BEEN TUNED and most make fantastic ammo and all make good ammo!! I have never ever got a set of dies from any factory that made as good of ammo as those that I have done this simple work with.

Kraky-



Thanks for a great, detailed post. I really appreciate the great info.



Ricciardelli- that is a great link. The photos are especially helpful.



Back to the reloading bench...



Jasper243

Kraky, you're right on to include this info. 'Tuning' my expanders has made a significant improvement in the measurable quality of my finished rounds. Also Partial full length resizing my cases has made a good difference in a few of my rifles performance--the bottom line!

Regards-Don.

Jasper, you did not state the powder charge you were using, but your problem is very characteristic of a very light , low powered load. The solution may be as simple as increasing the preasure of your load. As already stated it certainly could be the headspace.