Hello all,
Shot an interesting ladder test today, mostly just wanted to work up to find pressure on a new combination and thought I would try shooting it as a 400 yard ladder test. The rifle is a 243 on its second factory take off 1 in 9" twist barrel, that seems to be about a 1 MOA gun but I haven't worked a load through to its completion since I got it to see what it is really capable of.
This was my first try with 87 grain v max bullets, using IMR 4451. These cases were twice fired in this chamber Hornady, but were not all from the same lot. I'll be working up the loads with same lot brass. The brass used in the test had all been annealed using a salt bath after every firing, primer pockets have been uniformed, flash hole deburred, and trimmed to consistent length. Shoulders were bumped back about 3 thousandths with just a standard RCBS full length die, and the cases were dry tumbled to remove sizing lube. I used Winchester Large Rifle primers, necks were molly'd, and all charges were trickled up to as exact a weight as possible on an RCBS beam scale. Bullets were seated as long as possible while keeping 1 caliber/bullet diameter of bearing surface in the neck, which is about .050 off the lands. I didn't bother to check concentricity as I wasn't shooting groups.
This is a pretty light barrel, so I fired the shots about 2 minutes apart on a 35 degree day to try and keep the barrel from heating up.
I tried to keep track of the order of shots on the target, but the camera I set up shut itself off after 10 minutes and only captured the first 4 shots so i can't read the impacts on target like a traditional ladder test. Will have to find a new way to keep track of this, it seems like combined with chronograph data like a satterlee type test might be an interesting way to get to s load quickly.
What I found interesting was that the velocity was starting to climb, hit a flat spot, then dropped off, climbed again (but not as high?) Hit another flat spot, and then showed another climb. I wouldn't call this a perfect test (mostly because of the mixed lot brass and this isn't exactly a benchrest gun). It does make me wonder if I hit a point of diminishing returns on the powder charge. I never did hit pressure signs, but this is close to the max listed charges in a couple of different reloading data sources and over max in another so I didn't want to go any higher.
I thought that the first low velocity shot might be a fluke, but the rounds after it seemed to fall on a reasonable line too so maybe not?
Chronograph was a Caldwell optical, shots were taken from a bench with a front rest and rear bag.
Just wondering what other people's thoughts are. I see a couple places to play around charge wise, but will probably run a berger type seating depth test first. Might repeat the whole thing with another target camera just for grins.
Shot an interesting ladder test today, mostly just wanted to work up to find pressure on a new combination and thought I would try shooting it as a 400 yard ladder test. The rifle is a 243 on its second factory take off 1 in 9" twist barrel, that seems to be about a 1 MOA gun but I haven't worked a load through to its completion since I got it to see what it is really capable of.
This was my first try with 87 grain v max bullets, using IMR 4451. These cases were twice fired in this chamber Hornady, but were not all from the same lot. I'll be working up the loads with same lot brass. The brass used in the test had all been annealed using a salt bath after every firing, primer pockets have been uniformed, flash hole deburred, and trimmed to consistent length. Shoulders were bumped back about 3 thousandths with just a standard RCBS full length die, and the cases were dry tumbled to remove sizing lube. I used Winchester Large Rifle primers, necks were molly'd, and all charges were trickled up to as exact a weight as possible on an RCBS beam scale. Bullets were seated as long as possible while keeping 1 caliber/bullet diameter of bearing surface in the neck, which is about .050 off the lands. I didn't bother to check concentricity as I wasn't shooting groups.
This is a pretty light barrel, so I fired the shots about 2 minutes apart on a 35 degree day to try and keep the barrel from heating up.
I tried to keep track of the order of shots on the target, but the camera I set up shut itself off after 10 minutes and only captured the first 4 shots so i can't read the impacts on target like a traditional ladder test. Will have to find a new way to keep track of this, it seems like combined with chronograph data like a satterlee type test might be an interesting way to get to s load quickly.
What I found interesting was that the velocity was starting to climb, hit a flat spot, then dropped off, climbed again (but not as high?) Hit another flat spot, and then showed another climb. I wouldn't call this a perfect test (mostly because of the mixed lot brass and this isn't exactly a benchrest gun). It does make me wonder if I hit a point of diminishing returns on the powder charge. I never did hit pressure signs, but this is close to the max listed charges in a couple of different reloading data sources and over max in another so I didn't want to go any higher.
I thought that the first low velocity shot might be a fluke, but the rounds after it seemed to fall on a reasonable line too so maybe not?
Chronograph was a Caldwell optical, shots were taken from a bench with a front rest and rear bag.
Just wondering what other people's thoughts are. I see a couple places to play around charge wise, but will probably run a berger type seating depth test first. Might repeat the whole thing with another target camera just for grins.
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