Armory Sponsor
Posted: 3/21/2014 3:35:09 PM EDT
|
I've just recently began reloading .223 Rem and my first 10 rounds chambered and fired perfectly out of my M&P 15 Sport. Examined the cases and all appeared to be well. No signs of pressure using 24.5 grains of IMR 4064 and CCI 41 primers, pushing 55gr X-treme bullets down range.
So I sat down with a big bag of brass, resized, deprimed and trimmed them all. When I started to prime them, I started running into mucho problems; the dreaded crimped primer pockets. After doing some research I decided to opt for the Hornady Pocket Reamer to remove the crimp without prematurely stretching the primer pockets like I've read the Dillon SuperSwage does/can. I removed several crimps real careful like since it's a mighty sharp tool and was happy to find that the primers seated correctly and slightly below the surface; quite tight and as I've come to expect with rifle brass (I also load 30-30, 30-06 and 7.62x54r). Here's the hitch though. I decided to pop a blank, primed cartridge into my rifle and fire it and found that aside from being astonishingly loud, the primer itself set back out of the primer pocket by about 0.005". I tried a case that did not have to be reamed and had a normal rolled pocket, and the same thing happened. Seating primers in each of the pockets was "easy", but both were quite snug. The pocket was not loose at all on either case. What I'm wonder is, is this normal since I didn't fire a charged case and therefore lacked the pressure to take up the head space to keep the primer seated fully? My first 10 proofing loads didn't have to be reamed and didn't have any primer set back upon firing. Thanks for offering any suggestions or info. https://farm4.staticflickr.com/3802/13317789493_ae87d26f78_o.jpg https://farm3.staticflickr.com/2872/13317628395_493bcf1146_o.jpg |
It is normal. It is a poor man's way of determining cartridge head space. The only difference between what you see, and firing a fully loaded round, is that the case body stretches back to hit the bolt face at max. chamber pressure and re-swallows the primer cup. As fired full load rounds will have the primer cup flush with the case head face.
|
|
Welcome to Arfcom and the Reloading Forum. Yes normal. The Hornady primer crimp reamer has a built in stop and will not let you remove too much metal. It's a great tool. If adjusted correctly the Dillon Super Swage does an excellent job of swaging the primer crimp away. Like most tools, it can be adjusted incorrectly. It is possible to over swage if adjusted incorrectly. Not the tool's fault, the operator's.
|
|
As already stated above, normal due to low or lack of pressure.
Now, if you are working up loads with powder and bullets and you see this again, it will most likely be caused by the same thing, Low pressure. Even with a bullet and powder, a weak charge can cause a backed out primer. Looking at how far the primer backed out (.005) one can "assume" that .005 is the distance between the case head and the bolt face (headspace) of a chambered round. When firing full power loads the primer will still back out .005, but as the case expands under normal pressure the case head will be forced back up against the bolt face reseating the primer. This reseating of the primer with this much (.005) headspace can also flatten the primer even though the round is operating under acceptable pressures. |
Armory Sponsor