Anybody have any loads for the 200 grain Sierra Power Jacket bullets?

I've loaded that bullet with Reloader 7 but it is undersize for most 38-55 bores. You should slug your bore. If it is .377 or .378 you can get the correct diameter bullets from Barnes, if you want jacketed bullets. You can also get correct diameter cast bullets from a number of sources. I have had good luck with Laser-cast bullets.

For light plinking loads, 8 grains of Red Dot works well and shoots 1/2 to 3/4 inch groups at 50 yards. For a cast bullet hunting load, 20 grains of 4198 (either one) works well. For jacketed bullets I prefer Re 7. You'll need to be extra careful working up loads because the bore diameters vary so much.

I found the Sierra bullet and the 220 Hornady to be undersized for my Marlin Cowboy. They sailed through the target sideways at 25 yards. My bore slugs at .379 but does shoot the .377 Barnes and Winchester bullets very well.

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You have received excellent advice, I can only agree.

That's interesting. I didn't slug the bore on mine but I briefly scoped it for load workup and got MOA groups from the WW factory ammo and sub MOA groups with 3031 and the Hornady 220 grain flat point. That's a rifle I wish I still had.

Tom

I too have heard of Marlin Cowboy models that shot those bullets just fine. Haven't personally seen one. I had a Win. Crazy Horse Commemorative that shot them well and was the reason I tried them in my Marlin, really surprised me when they didn't work. That is why I suggest that 38-55 owners slug their bores before buying component bullets as it may save frustration later. I also have a NEF Target 38-55 that slugs a heavy .380 and surprisngly it shoot the .377 bullets very well. But a little wear on the bore may change that.

Makes sense. I wonder if they deliberately changed dimensions or if they are just inconsistent rifle to rifle. Their rifles in other calibers seem consistent. Hmmm. Beats me.

I purchased the 220 gr Hornady to try in my 38-55 Winchester Legendary Frontiersman but haven't tried them . I guess i will have to load some see if they shoot.

I've been casting for a few or my friends Marlins - two are 336 CBs and another is a 116 year old 1893 in 38-55. The bores on the newer 336 Cowboys came in at .379 - .380" and the old 1893 came in at .386" yikes!!! Lands are strong and sharp but the bore is dark. It is showing a little promise with the Lee 379-250 RF bullet as cast .380" with soft alloys but it looks like it'll end up getting relined.

The 336 Cowboys do very well with .379" cast bullets, the Ranch Dog TLC 379-235 RF in particular



Unique, Red Dot, Trail Boss, Re7, IMR 4198, 2400 have all produced excellent loads.

I can't wait to get my 336 CB in 38-55 (converting a Texan). GREAT caliber.

I have had pretty much the same experience when slugging the new Marlin bores. The two Win. Commemoratives I have slugged came out at .375-.376. An older mod.94 Win. came in at .378, so in my opinion the 38-55 lives up to the reputation that bore diameters are all over the place. I to shoot the Lee 250 and in the NEF unsized and loaded over 19gr of AA5744 it shoots groups much like the one in your photo. 26gr of RL7 is one of my favorite loads with the Lee bullet and and a plain base 255gr cast with and old Ideal mold. If I were building a 38-55 I believe I would specify a tighter bore in the 375-376 range as it would increase the number of bullets available for loading.

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"If I were building a 38-55 I believe I would specify a tighter bore in the 375-376 range as it would increase the number of bullets available for loading."

Then you would have a 375 Win.

True but just a suggestion for the folks not wanting to go through the search for suitable components. Example being I purchased 2 different bullet molds advertised as being 38-55 but neither dropped bullets large enough to be used in a bore larger than .377. So the search goes on prowling through the gun shows, small shops,looking for older molds, something I enjoy but not everyone does. Could have custom molds made but where is the fun in that.

.380, 260 gn cast performance and a stiff charge of RL-7,
mine runs 1852fps from a 24" brl.