I am reading all types of equations for bullet to land distance in the 38-55. Does it make a difference? Not in my rifles.
Of far greater importance to accuracy is Case length. Case length you say? Yep, because the 38-55 has a very shallow taper (6 degrees) from chamber to throat case length is important. The throat is the same diameter as the groove diameter so the oversized cast bullet will be swaged down in the throat long before lands (rifling) are encountered. Therefore, the case should not extend into the throat, otherwise the crimp will not be opened fully and a distorted bullet will result. Distorted bullets are never good for accuracy. Short cases cause other issues.
So how do we determine case length? The way that I use is to first determine what diameter cast bullet is to be loaded. Then load a dummy round with that bullet seated to the crimp groove but no crimp applied and see if it chambers with no undue effort, snug is good, very tight is not. The crimp will allow the round to seat deeper into the chamber and thus give a false fit indication. I begin with Starline long brass, 2.125 length, if it is too tight with the bullet of interest, I shorten the brass .010 and repeat the test. If the round is still too tight then shorten the case again. continue until a correct fit is obtained and you have your case length for that rifle. It works for me.
JBledsoe, your post, while perhaps well intentioned, contains information that is potentially harmful for a novice reloader. Bullet to land distance in the 38-55, which you dismiss as unimportant, happens to be controlled by case length. They go hand in hand so to speak. You can't have one without the other.
Furthermore, if you attempt to minimize bullet jump by using a case that is long enough to extend into the throat and impede bullet release you will have a lot more to worry about than a distorted bullet. How about a distorted rifle?? That is what will happen when pressure spikes because a case can't release the bullet quickly enough. Under no circumstances should one ever use a case that intrudes into the throat of the chamber.
Two of the multiple prerequisites for accuracy as well as safety require that you know the proper case length for your rifle and that you select a bullet profile that fits the throat/leade of your rifle. Hope this helps.
I don't want to get in the middle of anything here, but JBledsoe's probably forgotten more about the 38-55 than the rest of us have time left to learn. Just sayin.
Don't squat with yer spurs on!
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A practical and straight-forward way to make sure there's no interference. It catches either a case length interference, or a jamming the bullet against the lands interference.
As my chamber is about .07 inch longer than normal, I don't encounter length interference, and the bullets are a ways back from the lands when crimped in the crimp groove.
So far, limited experimentation confirms your thinking that there is not much effect on accuracy whether I have the bullets close to the lands or not.
Last edited by srf; 04-14-2013 at 06:54 PM. Reason: correct important typo
Team 39 #228
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Just buy the Starline 'long' length & call it good........
yes Starline makes two lengths in 38-55
My Marlin family.......
always looking for more........
TEAM 444 #187, Team 35 #7, Two Marlin 1894Cs, Remlin 1894C, 1894-44mag, 1952 Marlin 30-30, 1966 Texan 30-30. Glenfield 36G & two 30A's 30-30, 30-30 XLR, , 4- 35rem. 1951 SC, 1957, 1975 and 2008, 38-55 CB, M-375, 308 MX, 338MXLR, 444P, 444SS, , XS-7 22-250, XS-7 7mm-08 AI,
Well now boys and girls -- It seems we have some conflicting opinions on how a 38-55 cartridge case and bullet relate to a modern Marlin 336 Cowboy chamber. Let’s look at a few things. First a very fine chamber cast by JBledsoe. Note: there is no step in the chamber. Marlin chambered these rifles for the original 38-55 case length of 2.125”.
38-55 chamber cast (1) - Copy.jpg
Modern chamber reamers also show no step. They taper just as the chamber cast shows.
38-55 reamer with pilot.jpg
Jamming a cartridge into the chamber with sufficient force to push the bullet past the driving band and into the rifling is not a good idea. Then prying it out, like a bent nail, with the bolt and extractor isn’t conducive to accurate measurements on the remains.
There are numerous factors in the cartridge to chamber/throat relationship. Commonly:
Crimp groove to nose – length
Barrel riding flat or drive band
To name a few…
To be continued...
If the cartridge will initially chamber without engraving the bullet on the lands, you are good to go. In a tapered chamber, as in the 336 38-55 - .050” of bullet travel to the lands is of no consequence. It’s not half the width of the crimp groove. It will have no bearing on accuracy. Bullet diameter will be the key to that.
For you novice reloaders – Follow JBledsoe’s instructions. If your bullet lightly engraves the lands, measure that distance and shorten your brass accordingly.
This will leave the bullet diameter/shape and several other variations to consider. Welcome to the journey.
Best regards. Wind