338 Lapua or 338 Lapua Improved
I have a 338 Lapua barrel already and have been shooting it for two years. It is a 26" barrel and I get 3247 with 225 gr accubonds with less than 10 fps spread on my shots. I also had a reamer made up for a 30/338 Lapua Improved. I was thinking of using this reamer followed by a neck and then a throater to make a 338 Lapua Improved chambering.
So, today, I used my 5 foot drop tube and filled up the improved case with Retumbo that I had necked up to 338. Then, I took a standard 338 Lapua fired case and used the same 5ft drop tube and filled it up by dumping the powder from the improved case. I caught every granule of overflow and then weighed it and found that it was less than 3 grains of powder (actually 2.8 grains).
My new 338 barrel blank is 30" and I was ready to have it chambered in the 338 Lapua improved version. But, since I have seen such a small difference in useable powder capacity, I wonder if 2.8 grains of Retumbo is really worth the expense of the custom dies over a standard 338 Lapua in the same 30" barrel length from a performance standpoint.
So, my question is:
Has anyone tried this experiment before of one versus the other in the same length barrel and if so, which did you feel was the most worthwhile venture? Thanks in advance for the interest in this topic.