Accuracy problems

[Jagstang]

Hey guys. This is my first post. I’ve been casting for about 15 years and I’ve had some ups and downs but overall I’d say I’ve had pretty good luck with it for the most part. I cast about a dozen different bullets in the various pistol calibers. I’ve had some issues that have come up and I’ve revisited them a couple of times In the past few years but I can seem to figure it out. I’ve lurked here on many occasions, but I can’t find any threads that talk about this problem. So here I am.

I have two marlin 1894 cowboy rifles. First one is a JM .44 mag, the second one is a marlington .357. The bores slug at .431 and .3565

First problem. The .44 loves the 250 gr Keith bullet as far as accuracy but is a pretty rough feeder. This bullet will group 2.5-3” at 100 yds, which I think is pretty good considering that’s about as good as I can see with iron sights. I bought a Lee 200 gr rnfp mold to facilitate good feeding and be a nice lighter weight plinker bullet. Magnum brass only. This bullet has never shot well out of this rifle. I’ve tried varying hardness of alloy, lubed, powder coating, .430, .432, as cast, as cast fattened up with powder coat. Varying powder charges, specials, light, midrange and heavy magnums. It groups 12-18” at 100 yds with the best combination and at worst it won’t put three shots on a Uspsa target at 50. I gave up a couple years ago on this one and bought an Arsenal mold that is a 245 gr rnfp and the bearing surface portion is identical to a Keith but a rnfp rather than a swc nose. This will group 3”@100 sized at .432”

Now for the .357 Marlin cowboy repeater. This gun was bought last year. I previously cast both the Lee 358 125 RF and the Lee 358 158 RF for several years and both of these shot so well out of my s&w and uberti revolvers that I figured they’d be perfect for the marlin. I’ve stacked rounds on top of each other at 15-20 yds from the revolvers. The marlin can’t keep 3 shots on a 16”x16” target board at 50 yds with either lee bullet. I’m sizing .358” after powder coating. Special or magnum brass makes no difference. Special or magnum loads, no difference. Softer or harder alloy doesn’t seem to change anything. I gave up on these too and bought an Arsenal 162 gr rnfp will group 3/4” at 50 yds. Which is the best I’ve ever shot an iron sight rifle in my life. In a real quick test just to see, it grouped MP 135 gr 9mm rnfp sized .358” in 38 special brass and loaded to +p. These were almost all touching but only shot at 30 yds. But shows good promise.

I’m not so much concerned at this point in making the lee molds work since I’ve moved on to other molds that do work. But these three lee molds and these two rifles have sure been a head scratcher for the past few years and I was curious if any of you had seen this and would like to hear your thoughts. Thanks

[bmortell]

lee shoot very bad in my marlin too i thought maybe because it was bevel base but some of the ones you listed arent.

[chickenpot]

What is the twist rate of the marlington 357?

[StuBach]

Did you ever “Lee-ment” the Lee molds. Might be the cavities aren’t all uniform causing the variances in performance round to round. Especially when you aren’t sizing afterwards this could be an issue?

[Jagstang]

I actually am sizing these. .358” and .432”. As an experiment I tried shooting them as cast once and still had poor accuracy. I haven’t Lee-mented the molds. I’ll study up on that and maybe give it a try. Thank you.

[Jagstang]

Twist rate on the .357 is 1:16

[Larry Gibson]

What loads and velocities (if known) out of the rifles?

[Jagstang]

I have tried various loads in both rifles over the years. Ranging from light to magnum. The powder charges never really helped the poor accuracy. To be more specific, my usual load for 38 special loads are 5.2 gr HP38 with the 125 gr and 4.5 Gr unique with the 158, which I believe are 38 +p if I’m not mistaken. I could get out my chrono data on these for my revolvers but I don’t think I’ve actually ever chrono’d them through the rifle. For .357 mag I only load the 158 and it’s normally 13.5 gr of 2400 this load chrono’d at 1777 FPS from the marlin just last week. For the .44 I do 7.5 gr unique for the light load still using magnum brass, and 20.0 gr 2400. I’m away from my logbook at the moment and these are far enough in the past I can’t remember off the top of my head what they clocked at.

But again these are just my typical loads. I have experimented with a broader range of loads besides these with no real improvements in accuracy. I’ve tried other powders 4227, HS-7, cfe pistol, bullseye, power pistol. Just eventually gave up and bought the Arsenal and MP molds and the accuracy is there. At this point I’m just going to relegate the cartridges I’ve loaded with the Lee bullets to the revolvers and moving forward I’ll cast bullets from these other molds that’ll shoot good in both the revolvers and the rifles.

[waco]

My 1894 .357 shoots best with .361" bullets. Try fatter and see what happens.

[Larry Gibson]

"For .357 mag I only load the 158 and it’s normally 13.5 gr of 2400 this load chrono’d at 1777 FPS from the marlin just last week. For the .44 I do 7.5 gr unique for the light load still using magnum brass, and 20.0 gr 2400."

Based on my experience shooting cast bullets in various 357, 44 and 45 cal lever actions, including Marlins, you are pushing them too fast. I have consistently found best accuracy with PB cast bullets most often comes under 1400 fps and with the lighter weight 125 gr 38/357s and 200 gr 44s under 1200 fps. You might dig out the old chrony and load some of the 125 gr 38/357s and 200 gr 44s over Bullseye upwards of 1200 fps. I've found in leverguns with revolver cartridges if the best accuracy is wanted above 1500 fps then a GC'd bullet is best to use.

While getting very good accuracy out of revolvers with magnum cartridges using magnum level loads with light weight PB cast bullets I've yet to get acceptable accuracy with the same loads in lever rifles.