Blown primers...overpressure
08-15-2009, 07:57 PM
#1
Giant Nontypical
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Blown primers...overpressure
I was shooting the .243 AI yesterday and had 4 rounds blow/smoke the primers. They blew holes between the primer and case. The other rounds had a slight tight bolt lift but not bad at all. All the other primers were fine, not flat at all.
What could it be? Just too much powder?
I went ahead and pulled all the bullets and I'm starting over anyway...
What could it be? Just too much powder?
I went ahead and pulled all the bullets and I'm starting over anyway...
08-15-2009, 08:28 PM
#2
Typical Buck
Join Date: Dec 2004
Location: Nebraska
Posts: 601
I would make sure the bullet was NOT touching the lands, and would back the load off by at least .5-1 grains.
Might be the difference between standard and magnum primers as well.
Sticky bolt, means you are already well over-pressure in my safety world.
You should also check your bolt's extractor and firing pin for any physical damage.....
.
Might be the difference between standard and magnum primers as well.
Sticky bolt, means you are already well over-pressure in my safety world.
You should also check your bolt's extractor and firing pin for any physical damage.....
.
Last edited by LaneNebraska; 08-15-2009 at 08:34 PM.
08-16-2009, 07:06 AM
#3
Giant Nontypical
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how many loadings ya got on those brass? what brand are they? and do you notice a different "feel" to seating the primers. Check casehead expansion on one of the blown primer cases.
Thats the thing with custom chambers, If a min. spec reamer is used, the first pressure sign you'll see is the primer pocket gets a bit loose. Now is when you look for a happy medieum of velocity and case life. I get 3 firings from my 6.5 Gibbs, 5 from the 7mm AM.
RR
Thats the thing with custom chambers, If a min. spec reamer is used, the first pressure sign you'll see is the primer pocket gets a bit loose. Now is when you look for a happy medieum of velocity and case life. I get 3 firings from my 6.5 Gibbs, 5 from the 7mm AM.
RR
I'm going to load up some right now with 1.5 grs less and then work them up again...
08-16-2009, 08:35 AM
#4
Giant Nontypical
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Not jammed, just touching. But I'm also going to back them up a little more also. Same powder. Don't really have a reason for mag primers, I just always seem to use them...
08-16-2009, 10:16 AM
#5
Fork Horn
Join Date: Feb 2009
Posts: 107
pressure
use the same load and just seat them deeper, velocity would probably go up a tad and pressure go down by just giving them a lil jump.
Pete
Last edited by Pete D.; 08-16-2009 at 10:19 AM.
08-16-2009, 10:25 AM
#6
Giant Nontypical
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Old ones were 2.737 OAL, just loaded 9 at 2.730 and 47.0, 47.5, 48.0 grains instead of 48.5. Will test them out in a couple hours and see what happens. I have shot this load many times in another batch of Lapua brass and never had the primer thing happen...
08-16-2009, 10:49 AM
#7
Typical Buck
Join Date: Dec 2004
Location: Nebraska
Posts: 601
Will you run them over a chrony? And what bullet/weight ya shooting?
Last edited by LaneNebraska; 08-16-2009 at 10:51 AM.
08-16-2009, 02:25 PM
#9
Giant Nontypical
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Just shot them and the 47.0's were fine, then one out of three of the 47.5's blew a hole next to the primer and then I shot one 48.0 and it also did so I didn't shoot any more.
Could it be a bad batch of primers? Its the same load that I've shot over 50 times with no trouble before...??
Could it be a bad batch of primers? Its the same load that I've shot over 50 times with no trouble before...??