MP 258-640 in the 25/20wcf

[jwhite]

Spent the last few days experimenting with this 25 caliber bullet in my Marlin 25/20.

[jwhite]

Started out trying some various loads that have worked well in the past and had terrible luck with all of them. I even went as far as to remove the williams receiver sight and mount a 1x4 leupold for load testing. I finally found a little success with .7cc (3.4grains) of trailboss but even that was not spectacular. Everything else i tried produced groups of 3-5" at 50 yards.
The following are some of my chronograph results.
11grains of Data 68 1515fps
10.5grs of Data 68 1487fps
10grs Data 68 1413fps

6.5grs IMR 4227 1264fps
7.0grs IMR 4227 1360fps
7.5grs IMR 4227 1450fps

5.5grs 2400 1231fps
6.3grs 2400 1515fps

9grs 4198 1411fps

3.4grs Trailboss 1177fps

This rifle has always been a good cast bullet shooter and I am perplexed with this bullet, they cast wonderfully, perfect bases and nice fill out and powder coating came out great.

[square butte]

What diameter does this mold drop, and with what alloy? - Just out of curiosity. When I looked at the group buy for this mold, I found myself wishing that it's intended diameter was .259/.260 for those of us who have older rifles with worn bores which might need a larger diameter to shoot well. Next question - How old is the Marlin you are shooting it out of and how about bore diameter and condition?

[ole_270]

Looks a lot like my NOE 260283 which is my favorite bullet in my old Marlin 94. Mine has a faster than standard twist liner which may help with this longer bullet style. I use the bullets sized .260 over 9.2 gr 4198 for great accuracy. How does the bullet compare in length to the ones you've used before?

[jwhite]

Bullets drop right at 258 and end up at .259 once coated, I would prefer to have another .001 of diameter but not sure that this would make enough of a difference to explain the poor groups. Rifle is a Marlin 94 Classic with a pristine barrel. I am beginning to wonder if it just doesn't like powder coated bullets? I powder coated everything that i cast so will have to cast some more and try tumble lubing with alox and re-test. I actually tumble lubed a handful of the powder coated bullets with alox to try that and see it makes any difference in group size. The mold itself is wonderful to use and makes great bolts, no i just got to see if i can make them shoot. I have used longer bullets without any issues as long as speed was kept up, i will measure and compare lengths but this bullet is definitely shorter that the Meister 85gr bullet with has worked well in this rifle in the past.