Ladder test new brass
- Thread starter Justin B
- Start date
RegionRat
Gold $$ Contributor
No, but the next test will answer if there is a bias shift after the first cycle.
Sometimes that is acceptable and small, sometimes if you are on a narrow node you find you want to repeat that work with cycled brass and find a better load. Most times you will be just fine if you pay attention to your necks and the difference in new versus fired volume is small.
The smaller the case with a big delta from a cycle, the more likely to find an issue. Bigger cases mean that same volume difference is divided by a larger denominator.
Sometimes that is acceptable and small, sometimes if you are on a narrow node you find you want to repeat that work with cycled brass and find a better load. Most times you will be just fine if you pay attention to your necks and the difference in new versus fired volume is small.
The smaller the case with a big delta from a cycle, the more likely to find an issue. Bigger cases mean that same volume difference is divided by a larger denominator.
@Justin B, depending on your goals as well as the precision of your current reloading technique, you may or may not see a difference. I found that I only saw a difference between virgin brass and match level brass once my entire process became more refined. Now I only do testing with match quality prepped brass.
Not much info supplied with your question. So for me absolutely, I take all measurements on virgin Lapua Brass, neck diameter (tension) .200 line, base to shoulder.
Often in a min SAAMI chamber things don't move much. In the past I've learned a lot from virgin brass, like my 47L liked the tighter neck tension on the virgin brass and another like a little more shoulder clearance that I had with virgin. A lot of good data collected on the first firing and a base for comparison.
Often in a min SAAMI chamber things don't move much. In the past I've learned a lot from virgin brass, like my 47L liked the tighter neck tension on the virgin brass and another like a little more shoulder clearance that I had with virgin. A lot of good data collected on the first firing and a base for comparison.
Ned Ludd
Silver $$ Contributor
Part of that would depend on your intended use and precision requirements. I develop loads in virgin brass regularly, and I have no issues bringing loads in virgin brass to local F-Class matches. I first open the necks of Lapua cases (straight out of the box) with an oversized expander mandrel (~.001" under bullet diameter). Then, cases are sized using a bushing die with the correct bushing for whatever neck tension (interference fit) I want. Finally, I trim/chamfer the cases. The sizing die step does not really even touch the body/shoulder on virgin brass, but it's critical for obtaining consistent neck tension. Brass prepped in this manner can shoot very well.
In my hands, a good load developed using virgin brass need only be re-tweaked after the brass is fire-formed. I find that I typically have to reduce the charge weight from about 0.1 to 0.3 gr to maintain the same velocity obtained in the virgin brass. If I do that, the seating depth optimum is typically unaffected, although I usually check it to be sure. If you are doing a ladder-based approach, I suspect what you would see is that the ladder results don't really change much relative to each individual charge weight, but the whole ladder might be shifted at each charge weight by whatever change in the amount of powder it took to get back to the original (virgin brass) velocity. You could certainly go that route, but I've found that reproducing the original velocity of a well-tuned load in virgin brass once it has all been fire-formed will usually get you very close to where it was previously.
In my hands, a good load developed using virgin brass need only be re-tweaked after the brass is fire-formed. I find that I typically have to reduce the charge weight from about 0.1 to 0.3 gr to maintain the same velocity obtained in the virgin brass. If I do that, the seating depth optimum is typically unaffected, although I usually check it to be sure. If you are doing a ladder-based approach, I suspect what you would see is that the ladder results don't really change much relative to each individual charge weight, but the whole ladder might be shifted at each charge weight by whatever change in the amount of powder it took to get back to the original (virgin brass) velocity. You could certainly go that route, but I've found that reproducing the original velocity of a well-tuned load in virgin brass once it has all been fire-formed will usually get you very close to where it was previously.
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