paborn
06-29-2013, 07:23 PM
I remember reading of someone who wanted documented cases of chamber ringing, so here is my story.
I've shot about 7,000 rounds of Lyman 311284 GC at 210 grains out of a Winchester 70 XTR 30-06 over 20 grains of Alliant 2400 using WLR primers. This load shot under 2 inches at 100 yards without any filler, but got more consistent velocity and accuracy of close to an inch with a dacron filler. I'd always heard about chamber ringing, but never thought it would be a problem.
I started loading a Lee/Harris 155 grain in 7.62x39 and thought I'd try light loads in my 30-06. Loaded 20 each of 20 and 25 grains of Alliant 2400. Dacron was use to keep the powder down on the primer. Imagine my surprise when both loads printed 1.2 inches at 100 yards. The 20 grain load was at 1780 fps. Extraction was a little sticky, especially with the 25 grain loads. Both of these loads are well under max based on Lyman's Cast Bullet Handbook. I also loaded some of my standard 311284 loads.
Again imagine my surprise when close examination of the cases showed a 0.0015 expansion ring just where the base of the bullet would be, hence the cause of the sticky extraction. This was definitely from the Lee bullet loads, as the many prior Lyman loads were all seated to the juncture of the case neck. Case ringing occurred from firing 40 loads, and I believe the 25 grain load was the primary culprit.
I tried to think what I did different, if anything, with these loads. What I came up with is that for these loads I used a pencil to push the small tuft of dacron into the case, and reversed the pencil and used the eraser end to push the dacron down onto the powder. In the past I'd used a smaller diameter rod and I thought left the dacron looser.
Since I loaded the 311284 loads the same way, I took a second, closer look at a brass case after firing a Sierra 165 grain BT hunting load with 58 grains of IMR 4350. I figured the higher pressure would let the brass flow in any rings and show up better.
Lo and behold, as well as a 0.0015 ring where the base of the Lee bullet was, there was also a slight ring where the base of the Lyman bullet would be.
What I take from this is that as long as the dacron was loose and filled the airspace under the bullet, I was OK, but when I tamped the dacron down onto the powder and left an airspace between the tamped dacron and the bullet base I caused the ringing.
To repeat, it only took 40 rounds to ring the middle of the neck in the chamber with the Lee load, Personally, with the sticky extraction, I think it took less than that.
Well, as I like the rifle and the barrel as I've put good open sights on it to use with quick release scope mounts, I'm going to get it rebored to 35 Whelen.
Just talked to Jesse Occumpaugh at JES Rifle Reboring, and I can get the rifle rebored to 35 caliber and the neck and throat recut for the reasonable price of $225.
Guess I need a new 30-06.
Paborn
I've shot about 7,000 rounds of Lyman 311284 GC at 210 grains out of a Winchester 70 XTR 30-06 over 20 grains of Alliant 2400 using WLR primers. This load shot under 2 inches at 100 yards without any filler, but got more consistent velocity and accuracy of close to an inch with a dacron filler. I'd always heard about chamber ringing, but never thought it would be a problem.
I started loading a Lee/Harris 155 grain in 7.62x39 and thought I'd try light loads in my 30-06. Loaded 20 each of 20 and 25 grains of Alliant 2400. Dacron was use to keep the powder down on the primer. Imagine my surprise when both loads printed 1.2 inches at 100 yards. The 20 grain load was at 1780 fps. Extraction was a little sticky, especially with the 25 grain loads. Both of these loads are well under max based on Lyman's Cast Bullet Handbook. I also loaded some of my standard 311284 loads.
Again imagine my surprise when close examination of the cases showed a 0.0015 expansion ring just where the base of the bullet would be, hence the cause of the sticky extraction. This was definitely from the Lee bullet loads, as the many prior Lyman loads were all seated to the juncture of the case neck. Case ringing occurred from firing 40 loads, and I believe the 25 grain load was the primary culprit.
I tried to think what I did different, if anything, with these loads. What I came up with is that for these loads I used a pencil to push the small tuft of dacron into the case, and reversed the pencil and used the eraser end to push the dacron down onto the powder. In the past I'd used a smaller diameter rod and I thought left the dacron looser.
Since I loaded the 311284 loads the same way, I took a second, closer look at a brass case after firing a Sierra 165 grain BT hunting load with 58 grains of IMR 4350. I figured the higher pressure would let the brass flow in any rings and show up better.
Lo and behold, as well as a 0.0015 ring where the base of the Lee bullet was, there was also a slight ring where the base of the Lyman bullet would be.
What I take from this is that as long as the dacron was loose and filled the airspace under the bullet, I was OK, but when I tamped the dacron down onto the powder and left an airspace between the tamped dacron and the bullet base I caused the ringing.
To repeat, it only took 40 rounds to ring the middle of the neck in the chamber with the Lee load, Personally, with the sticky extraction, I think it took less than that.
Well, as I like the rifle and the barrel as I've put good open sights on it to use with quick release scope mounts, I'm going to get it rebored to 35 Whelen.
Just talked to Jesse Occumpaugh at JES Rifle Reboring, and I can get the rifle rebored to 35 caliber and the neck and throat recut for the reasonable price of $225.
Guess I need a new 30-06.
Paborn