Loading for the 6mm Bench Rest Magnum

roysclockgun · December 13, 2009, 12:29 PM

Well, I have worked up over a dozen loads for this E. Brown, falling block rifle, Model 97d, in 6mm BRM. All test loads have used 6mm Speer 70gr. TNT, hollow point bullets. Only one of those loads produced groups over 1 1/2" at 100 yards and on that load, although I was not getting hard extraction, the primers were looking a tad flatter. That was 32.4gr. of H380. Other loads using IMR4064, IMR4895 and H380, were turning in consistant groups right in the 1" range at 100 yards. All groups mentioned here were shot at 100 yards.
The two best loads, both producing 1/2" groups, or a little less, were: 32gr. of H380 and 32 grains of IMR4064. I have not chronographed any of these loads, but now that I have settled on these two, I will check out MV. All test loads used Winchester Large Rifle Primers. Cases were kept separated by brand and no one brand stood out. Although R-P was the hardest to neck down from the parent 30-30 brass to 6mm BRM. When I used brass made by; Winchester, Frontier and Federal, all necked down with ease.
Working up loads for this proprietary cartridge is only worthwhile for those who like challenges involving hand loading. The brass right from E. Brown Co. is headstamped "30-30", so with once fired 30-30 readily availble for free at my local range, why buy the brass from Brown.
The drill to create 6mm BRM is fairly simple. First the usual tumbling to get the brass cleaner. Then all 30-30 brass is run through a 7-30 Waters full length resizer/deprimer. Following that, the brass, now necked down to 7mm, is run through the 6mmBRM full length resizer. This process gets us brass that is stepped down twice, but the final shoulder still needs to be fire formed. Before fireforming, the brass must be trimmed back to the correct length. I then loaded all the brass with 32gr. of IMR4064, which it turns out not only fire forms nicely, but also was capable of groups that 99% of all hunters that I have ever known, would be happy with! During fire forming, I was getting groups measuring center to center, 1" to 1 1/2", depending on my own skills on any given day.
Why did I not simply use the load recommended by E. Brown Co.? The answer is simple. I have a lot of bullets and propellant in my shop. None of what I have on hand, dovetailed with Brown's load, using V-160 VihtaVuori propellant and 80gr. Speer bullets. So, I checked out other cartridge loads and began at very low levels, working up to what I am finding works.
Anyone having a souce for other loads, kindly let me know.
Best,
Steven A.

December 13, 2009, 12:29 PM	#1
roysclockgun Junior Member Join Date: December 13, 2009 Posts: 2	Loading for the 6mm Bench Rest Magnum Well, I have worked up over a dozen loads for this E. Brown, falling block rifle, Model 97d, in 6mm BRM. All test loads have used 6mm Speer 70gr. TNT, hollow point bullets. Only one of those loads produced groups over 1 1/2" at 100 yards and on that load, although I was not getting hard extraction, the primers were looking a tad flatter. That was 32.4gr. of H380. Other loads using IMR4064, IMR4895 and H380, were turning in consistant groups right in the 1" range at 100 yards. All groups mentioned here were shot at 100 yards. The two best loads, both producing 1/2" groups, or a little less, were: 32gr. of H380 and 32 grains of IMR4064. I have not chronographed any of these loads, but now that I have settled on these two, I will check out MV. All test loads used Winchester Large Rifle Primers. Cases were kept separated by brand and no one brand stood out. Although R-P was the hardest to neck down from the parent 30-30 brass to 6mm BRM. When I used brass made by; Winchester, Frontier and Federal, all necked down with ease. Working up loads for this proprietary cartridge is only worthwhile for those who like challenges involving hand loading. The brass right from E. Brown Co. is headstamped "30-30", so with once fired 30-30 readily availble for free at my local range, why buy the brass from Brown. The drill to create 6mm BRM is fairly simple. First the usual tumbling to get the brass cleaner. Then all 30-30 brass is run through a 7-30 Waters full length resizer/deprimer. Following that, the brass, now necked down to 7mm, is run through the 6mmBRM full length resizer. This process gets us brass that is stepped down twice, but the final shoulder still needs to be fire formed. Before fireforming, the brass must be trimmed back to the correct length. I then loaded all the brass with 32gr. of IMR4064, which it turns out not only fire forms nicely, but also was capable of groups that 99% of all hunters that I have ever known, would be happy with! During fire forming, I was getting groups measuring center to center, 1" to 1 1/2", depending on my own skills on any given day. Why did I not simply use the load recommended by E. Brown Co.? The answer is simple. I have a lot of bullets and propellant in my shop. None of what I have on hand, dovetailed with Brown's load, using V-160 VihtaVuori propellant and 80gr. Speer bullets. So, I checked out other cartridge loads and began at very low levels, working up to what I am finding works. Anyone having a souce for other loads, kindly let me know. Best, Steven A.