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+--- Thread: Excessive Pressure II (/showthread.php?tid=7287)
Excessive Pressure II - keystone183 - 02-10-2014
**WOW. Ok, very sorry. Not even the same subforum. Having serious issues this evening....**
Very sorry for this, but i could not reply and post pics for some reason. Someone please feel free to merge?.....
I will have to see if i can borrow some calipers to measure the bolt face. Keep you posted.
Ok, here are the pictures. Marked a factory hornady 123sst. Inserted in mag, dropped bolt from locked back position. Extracted taking care not to let bullet touch extension (possibly not enough?). I think i have uploaded the pics in sequential order. Quarter turn at a time. Also, something i hadn't noticed before all of this, but do now. Any reason to be concerned about the light indentation on the primer?
[ATTACH=CONFIG]4573[/ATTACH][ATTACH=CONFIG]4574[/ATTACH][ATTACH=CONFIG]4575[/ATTACH][ATTACH=CONFIG]4576[/ATTACH][ATTACH=CONFIG]4577[/ATTACH]
Excessive Pressure II - PigOPs - 02-10-2014
Looks like the round is kissing the freebore. I don't see land marks at all (someone will correct me if I'm wrong.) The pock mark is from the firing pin design in the ar15. It bounces off the primer every time the bolt cycles a round. Perfectly normal.
Excessive Pressure II - JASmith - 02-10-2014
Have you tried the same operation without using the dye?
That kiss is so light it might be hard to see on a plain bullet.
Excessive Pressure II - Kikn - 02-10-2014
PigOPs Wrote:Looks like the round is kissing the freebore. I don't see land marks at all (someone will correct me if I'm wrong.) I pick mark is from the firing pin design in the ar15. It bounces off the primer every time the bolt cycles a round. Perfectly normal.
That is pretty much the way I see it also.
Excessive Pressure II - jluck - 02-10-2014
Where is the excessive pressure?
Excessive Pressure II - Kikn - 02-10-2014
jluck Wrote:Where is the excessive pressure?
This thread is an update from another thread the op was unable to locate.
Excessive Pressure II - LRRPF52 - 02-10-2014
That mark is coming from something during a rotational movement of the cartridge, it appears, probably from the barrel extension, but I would have to have it in hand to tell. You need to keep it from contacting the extension during insertion and extraction.
Don't use a magazine. Drop the cartridge into the chamber. Carefully close the bolt on it.
Extract it while keeping your index or pinky finger in the ejection port so the ejector can't push it into the extension teeth. Let it fall from the action, then inspect.
Here is the other thread: http://www.65grendel.com/forum/showthread.php?7980-Excessive-Pressure&p=86529#post86529
He definitely is seeing excessive pressure signs when firing the rifle:
Excessive Pressure II - keystone183 - 02-11-2014
LRRPF52 Wrote:That mark is coming from something during a rotational movement of the cartridge, it appears, probably from the barrel extension, but I would have to have it in hand to tell. You need to keep it from contacting the extension during insertion and extraction.
Don't use a magazine. Drop the cartridge into the chamber. Carefully close the bolt on it.
Extract it while keeping your index or pinky finger in the ejection port so the ejector can't push it into the extension teeth. Let it fall from the action, then inspect.
Here is the other thread: http://www.65grendel.com/forum/showthread.php?7980-Excessive-Pressure&p=86529#post86529
He definitely is seeing excessive pressure signs when firing the rifle:
Marks are all the way around. Not just one. And appears to be two different levels. Did level best keeping this one of the extension. Short on time lately so just one pic for now. Same marks all the way around.
Sorry about this whole two threads deal...
[ATTACH=CONFIG]4591[/ATTACH]
Excessive Pressure II - PigOPs - 02-11-2014
That round looks to be kissing the lands... IDK
Excessive Pressure II - Bwild97 - 02-11-2014
keystone183 Wrote:Marks are all the way around. Not just one. And appears to be two different levels. Did level best keeping this one of the extension. Short on time lately so just one pic for now. Same marks all the way around.
Sorry about this whole two threads deal...
[ATTACH=CONFIG]4591[/ATTACH]
There is definitely contact with the chamber on that round.
Excessive Pressure II - LRRPF52 - 02-11-2014
Something fishy going on with that one:
Excessive Pressure II - keystone183 - 02-12-2014
?? What is wrong with it?
Excessive Pressure II - LRRPF52 - 02-12-2014
Those strange marks on the projectile. I don't know how you pull that off, but they are obviously there.
Did you try it with magic marker as well?
Edit: My bad. I see it now. I've been looking at so many of these from these barrels over the past few days, I have a hard time keeping track of which is which.
Excessive Pressure II - keystone183 - 02-12-2014
LRRPF52 Wrote:Those strange marks on the projectile. I don't know how you pull that off, but they are obviously there.
Did you try it with magic marker as well?
Edit: My bad. I see it now. I've been looking at so many of these from these barrels over the past few days, I have a hard time keeping track of which is which.
No problem. My use of separate threads obviously isn't helping...
Any idea what might cause that?
Excessive Pressure II - LRRPF52 - 02-12-2014
A defect in the chamber.
Excessive Pressure II - keystone183 - 02-12-2014
LRRPF52 Wrote:A defect in the chamber.
LOL. So, shoot it to "break it in" right?
Excessive Pressure II - LRRPF52 - 02-12-2014
No. Either have a competent gunsmith analyze it and make recommendations, or return it.
Looks like a bur or something is scribing the projectile circumferentially. Whatever it is, it needs to be taken out.