RCBS .32-90-CM 632 in Marlin Cowboy

[tomf52]

Anybody shoot this combo? Bought the rifle back in Jaanuary and just now found the load it likes with this bullet. What a nightmare getting any kind of accuracy from it, but now seem to have it. Anyone out there go through the same thing?

[35remington]

Would be interested in hearing of your experiences.

I have gone through something like this with the RCBS 85-CM in .25-20, but after learning the hard way what to do, I think it's my favorite .25-20 bullet.

[tomf52]

In a nutshell, it was a lesson in taking advice from others who you thought were knowledgable and not thinking for yourself. I started out with the Lee 90 gr SWC and got load info from a "guru" on another cast bullet sight. Taking his word as gospel I worked around the 3.5 gr range of Bullseye that was recommended. The number was not a single occurence misprint as he repeated it many times in many communications. The working number for this bullet was actually 2.5 + or -. Never did get that particular bullet to shoot real well either. Went to the RCBS 90 and worked around the same powder charges with reasonable success, but found my best results with W 231. Am now playing with this powder but have gotten some pretty respectable groups out of it. In the future I think I will be more inclined to follow my own intuition. If nothing else , I have learned to really like W231 as it burns so much more cleanly and meters far more accurately than Bullseye. What happened with your loads? Tom.

[35remington]

Well, with the RCBS 25 caliber bullet, the generous lube grooves overlubricate the bullet, and when lube was omitted from the grooves and used with unhardened wheelweights the lube grooves collapsed with many loads, especially faster powders. Filling all the lube grooves resulted in low point of impact from the first shot out of the barrel, even in one conditioned from previous firing (this was a pain while hunting). As the barrel collected more lube, enlarged groups and fliers resulted. Then, occasionally, the barrel would purge and accuracy would be fine for a couple of groups, and then start throwing fliers and big groups would again follow.

The remedy was to harden the bullet through quenching, use light amounts of LLA or JPW, and experiment with loads.

I found no load with this plainbase bullet that gave accuracy above 1500 fps with filler or not, but below that speed accuracy was very fine, with my best loads averaging a little more than a half inch at fifty yards.

A good .25-20 OTT barrel helped some too, so I wasn't stuck with a crappy chamber that seems to plague a lot of rifles in this caliber.

All loads with slower powders at moderate levels (2400, 4227, etc.) were noticeably position sensitive and benefitted from dacron. The very best accuracy was with these powders that gave velocities of 1250-1350 fps or in that region. H4198 worked fine when running just below the threshold 1500 fps with more impact if needed. Noticeably more noise though, with a fair amount of unburned powder that did not seem to harm accuracy.

W231 was a very good fast powder. 3.0 grains or a tiny bit over depending upon lot would give 1120-1130 fps with mild report and good killing power with the flatpoint bullet. Accuracy was also very good but slightly behind the slower powders like 2400.

[hyoder]

I'm using a similar Lyman 311419 cast with approx #2 alloy in a Marlin 32 H&R with AA No. 7 and getting <2" groups at 100m

[tomf52]

Hyoder - -May I ask how much AA7 you are using to get those results? Thank you, Tom.