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Posted: 12/9/2011 6:20:56 PM EDT
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Shot some reloads this afternoon and noticed black around the cartridge rim on some of the cases. These were 308 Remington brass with Nosler 125 BT's and 38 grains of H4895 (reduced recoil load) and CCI primers. Four out of the ten reloads looked like this. Three were fired from an AR-10 and one from a Remington 700. The other six did not have the black. Curious as to what this might be. Tried some pictures but they didn't turn out very good. <a href="http://s1196.photobucket.com/albums/aa417/kdmax1/?action=view¤t=308-1.jpg" target="_blank">http://i1196.photobucket.com/albums/aa417/kdmax1/th_308-1.jpg</a> <a href="http://s1196.photobucket.com/albums/aa417/kdmax1/?action=view¤t=308-2.jpg" target="_blank">http://i1196.photobucket.com/albums/aa417/kdmax1/th_308-2.jpg</a> <a href="http://s1196.photobucket.com/albums/aa417/kdmax1/?action=view¤t=308-3.jpg" target="_blank">http://i1196.photobucket.com/albums/aa417/kdmax1/th_308-3.jpg</a> Hard to see detail your pics are soo small. Are you clicking on the IMG code under the pic in Photobucket? Then just paste in thread. 
My pics come out this size. |
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Here are some better pictures. http://i1196.photobucket.com/albums/aa417/kdmax1/308-5-1.jpg http://i1196.photobucket.com/albums/aa417/kdmax1/308-4.jpg The top case looks like the neck is cracked. With really low pressure to make the case head black, I would expect to see at minimum a black streak down one side of the case. The shoulders certainly indicate low pressure here. |
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Here are some better pictures. http://i1196.photobucket.com/albums/aa417/kdmax1/308-5-1.jpg http://i1196.photobucket.com/albums/aa417/kdmax1/308-4.jpg The top case looks like the neck is cracked. With really low pressure to make the case head black, I would expect to see at minimum a black streak down one side of the case. The shoulders certainly indicate low pressure here. I examined the case neck closely and its not cracked or split. There is scratch down the neck which is highlighted by the black discoloration and looks like a scratch. I noticed similar scratches on several of the cases. There are no black streaks down the sided of any of the cases. |
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Case isn't sealing the chamber, usually a sign of low pressures. If the discoloration on the shoulder of the cartridge indicates low pressure, I'm sure you're right. How would the gas pass down the side of the case and collect on the rim without leaving a mark on the side of the case? None of the cases had any discoloration down the sides. Would a crimp help this condition? When I used a load of 12gr of Trail Boss, Hornady 150gr SP and CCI 200 primers, the felt recoil was considerably less and there were no signs of low pressure, i.e. discoloration on the case shoulders. Also most of the low pressure signs were from the AR-10 and not the Remington 700. I'm assuming this is because the Remington has a tighter chamber? |
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Second batch of pics are much better. Well done.
Now that you have posted the load, it's easy to say with that load, expect the gas marks. You are not shooting standard pressure rounds, cases don't expand normally, so dirty cases. Everyone saying low pressure round was correct. |
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Quoted: If the discoloration on the shoulder of the cartridge indicates low pressure, I'm sure you're right. How would the gas pass down the side of the case and collect on the rim without leaving a mark on the side of the case? None of the cases had any discoloration down the sides. Would a crimp help this condition? When I used a load of 12gr of Trail Boss, Hornady 150gr SP and CCI 200 primers, the felt recoil was considerably less and there were no signs of low pressure, i.e. discoloration on the case shoulders. Also most of the low pressure signs were from the AR-10 and not the Remington 700. I'm assuming this is because the Remington has a tighter chamber? It may have collected on the side of the case but was scraped off during extraction. -Deke |
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