Ok so I have read, and read, and read... did I say I have read about this. I am sorry but this will be long so I can provide as much information as possible.
Info
Brass that has experiences this phenomenon:
Hornady 3rd load
FMMG 2nd Load
Gunwerks 2nd load
Dies: Whidden full length and micro seating dies.
Powder: H1000 @ 78.6g
Bullet: 208 ELDM
OAL: 3.51"
Primer : CCI Magnum Primers
Rifle is a GA Precision built 300WM with a 24" barrel using an AEM5 30 cal can.
Ok so I loaded up some brass to fire form the brass to my chamber. After the first shots with the new brass all the brass averaged a head space size (using the provided Whidden gauge) of 2.269. I resized the brass pushing the shoulder back .002, (or so I thought, the push back was actually .007) the first time this problem occurred so I corrected the die to only push the shoulder back by .002) during the full length resizing process for the FMMG and the Hornady brass.
The very next shots exhibited a shoulder deformation (referred to as dimpling in the reading I have done) and some signs of head case separation and cracked cases at the head. So I trashed all the brass and ordered up some of the Gunwerks brass.
In the time I waiting for delivery I did run a bore scope in the barrel and looked for any sort of damage or carbon rings. There were no signs of any issues the barrel looks good. I then did a thorough cleaning of the bore and the barrel anyway just to start with a clean setup. I remeasured the head space two different way. I used the Hornady tool and measured the head space several times. I then disassembled the bolt including the plunger and used an unused NEW Hornady case I still had and seated a bullet long. I seated and re-seated until there was no bolt hang up and measured that. I ran a go and no go gauge and all checked out just fine.
One I received the brass and loaded 50 rounds to fire form 50 cases. I loaded 10 of each of the following charge weight 72.5, 73, 74, 75, 75.5 grains of H1000 with the 208 ELDM's, same primers all at an OAL of 3.51". I took those fired cases and measure the head space once again on several cases. I adjusted my resizing die out making sure not to push the shoulders back at all so I just resized the body and the neck. I checked the case OAL and all was within spec. This time I loaded 75.5 G H1000 as this is what yielded the most consistent ES of all the fire form loads.
I fired 10 rounds and while I did not have any case separation I did experience the dimples on two of the 10 case shoulders after firing. So I read and researched some more and decided maybe I was not getting enough pressure so I re-seated the rest of the same loads to an OAL of 3.43.
I went back to the range and shot 10 rounds of the 1 time shot Gunwerks brass with 75.5g of H1000 with an OAL of 3.43" @ 2910fps on average with no shoulder issues. Just for grins I had some of the same rounds in the bag loaded to and OAL of 3.51" and the first shot dimpled the shoulder again so I shot no more that day.
I am lost. I have been reloading for over 20 years and never have I experienced case head separation or this dimpling of the brass like my 300WM does. Any advise?
Info
Brass that has experiences this phenomenon:
Hornady 3rd load
FMMG 2nd Load
Gunwerks 2nd load
Dies: Whidden full length and micro seating dies.
Powder: H1000 @ 78.6g
Bullet: 208 ELDM
OAL: 3.51"
Primer : CCI Magnum Primers
Rifle is a GA Precision built 300WM with a 24" barrel using an AEM5 30 cal can.
Ok so I loaded up some brass to fire form the brass to my chamber. After the first shots with the new brass all the brass averaged a head space size (using the provided Whidden gauge) of 2.269. I resized the brass pushing the shoulder back .002, (or so I thought, the push back was actually .007) the first time this problem occurred so I corrected the die to only push the shoulder back by .002) during the full length resizing process for the FMMG and the Hornady brass.
The very next shots exhibited a shoulder deformation (referred to as dimpling in the reading I have done) and some signs of head case separation and cracked cases at the head. So I trashed all the brass and ordered up some of the Gunwerks brass.
In the time I waiting for delivery I did run a bore scope in the barrel and looked for any sort of damage or carbon rings. There were no signs of any issues the barrel looks good. I then did a thorough cleaning of the bore and the barrel anyway just to start with a clean setup. I remeasured the head space two different way. I used the Hornady tool and measured the head space several times. I then disassembled the bolt including the plunger and used an unused NEW Hornady case I still had and seated a bullet long. I seated and re-seated until there was no bolt hang up and measured that. I ran a go and no go gauge and all checked out just fine.
One I received the brass and loaded 50 rounds to fire form 50 cases. I loaded 10 of each of the following charge weight 72.5, 73, 74, 75, 75.5 grains of H1000 with the 208 ELDM's, same primers all at an OAL of 3.51". I took those fired cases and measure the head space once again on several cases. I adjusted my resizing die out making sure not to push the shoulders back at all so I just resized the body and the neck. I checked the case OAL and all was within spec. This time I loaded 75.5 G H1000 as this is what yielded the most consistent ES of all the fire form loads.
I fired 10 rounds and while I did not have any case separation I did experience the dimples on two of the 10 case shoulders after firing. So I read and researched some more and decided maybe I was not getting enough pressure so I re-seated the rest of the same loads to an OAL of 3.43.
I went back to the range and shot 10 rounds of the 1 time shot Gunwerks brass with 75.5g of H1000 with an OAL of 3.43" @ 2910fps on average with no shoulder issues. Just for grins I had some of the same rounds in the bag loaded to and OAL of 3.51" and the first shot dimpled the shoulder again so I shot no more that day.
I am lost. I have been reloading for over 20 years and never have I experienced case head separation or this dimpling of the brass like my 300WM does. Any advise?
