Saturday, October 30, 2010

Review: Lee 379-250 RF bullet in the Marlin 336 Cowboy

Here is my review of the Lee 379-250 RF bullet in my 38-55 caliber Marlin 336 Cowboy.

Lee 379-250 RF as cast with a Lyman #2 approximation alloy - Weight 252 gr. average.

The cast weights range from 254 grains for 20/1 alloy down to 245 grains using harder alloys.  In my 336 Cowboy the softer alloys are showing the most promise with this bullet.

38-55 Lyman Data

10 grains of Unique will propel this bullet to just under 1300 fps in my rifle and it also appears to be the most accurate.  There is enough rear sight elevator range to give me right on holds out to 200+ yards.

50 yards over Unique

5.6 grains of Unique gets 910 fps and out to 50 yards is only slightly less accurate than the 10 grain load.

My testing with 2400 was limited as the accuracy was quite poor in the loads I tried.  In my rifle 16 grains would get the Lee bullet going 1511 fps avg.

16.5 grains of SR 4759 averages 1506 fps and is VERY consistent with Standard Deviations of less than 10 fps.  This load is also showing some real accuracy potential.  I believe this load would match the upper levels of the original black powder loadings.  The load data predicts the pressure levels to be well inside the capability of the Marlin's strength and examining the fired cases appears to bear that out.  Using Wind's Magi-Lube - Beeswax (5) Crisco (4) and Vaseline (1) - there is little to no sign of leading after 20 shots.  I have  not yet tried this load on the long range dingers but I suspect it may allow me to take at least a cover hold sight picture on the 400 yard dinger.

Recovered Lee Bullets fired into a dry sand backstop.  The 20/1 alloy at 1400-1500 fps expanded the noses to more than 45 caliber (smallest) and retained a most if not all of their weight.  The actual weight of the recovered bullets was greater than the cast weight as there was a good bit of sand became embedded in the bullet.  Bullets were recovered 8-9" deep.

For those looking for an inexpensive general purpose bullet mold that is a proven performer in 38-55 Marlins I would recommend it the Lee.  There are those that dislike the bevel base but I've experienced no issues with it.

Here is some video of it in use.

38-55 Winchester Starline Brass - A Case Study

Starline finally did a run on the 38-55 2.125" brass and 500 of them arrived on my Doorstep Grin

I tried to bump it up to 1,000 but they didn't have the inventory...  Undecided

Starline 2.125 and Winchester 38-55 brass

Right out of the box

Side by side comparison

The Lee 379-250 RF shoots very well in both W's and my 336 Cowboys.  With the Winchester brass the Lee bullet must be sized to .379" in order to cycle into W's and mine will cycle them as cast.  His shoots the .379" sized bullets very well and mine has a definite preference for the larger as cast variety.

Lee bullet as cast

The as cast Lee bullet in Starline Brass wide dimension is .395"  Loaded with the (excellent) RCBS Cowboy dies, crimping die set ~5/8 of a turn past touching.

The Winchester brass loaded with an as cast Lee Bullet.  This round will cycle easily through my CB but NOT W's.   With the Starline brass and the fatter as cast bullet it will cycle easily in his rifle.

The OAL for the Lee bullet in the Starline 38-55 2.125" case is 2.530" using all of the crimp groove. It cycles flawlessly through my CB.  Comparatively the OAL I've been using with the Winchester/Lee combo is 2.500"

A 2.550" OAL will cycle through the Marlin 336 Cowboy's chamber.

In tests over the chronograph there have been no appreciable differences in velocity between the Starline and Winchester Brass.  Accuracy too seems to be unaffected.