38-55 Win neck tension and crimp: how much?

[GSSP]

This seems to be the appropriate forum to ask this question; "dies". So here goes.

For my new Uberti 1894 (38-55 Win), I ordered some bullets from Montana Bullet Works and they arrived the other day. Gorgeous bullets! Exceptionally well packed. 265 gr and 278 gr LBT, GC, air cooled so 15 BHN. My bore is measuring .382" so Bruce made them as big as he could; .381". With new standard length Starline brass, run through RCBS Cowboy dies I had the .376" expander in place(Cowboy dies also come with a .379" expander) and my measurements tell me i'm getting .007" neck tension. Figured with the GC in place the tight neck is NOT swaging the entire bullet diameter down as though a PB might. Do you concur or should I try the .379" expander to get what should be .004" neck tension? FYI, I going to start with 27 gr of H4895 and work up to 31.0 gr in 1 gr increments with the 278 gr bullet first; Fed 210 primer. 2nd question.....Seated so the freshly trimmed case (2.075") mouth is just at the top of the crimp groove then with a LFC die crimping the mouth to just SAAMI spec of .392". Comparing the measurements between the bullet's first driving band (.381") and the case mouth (.392"), should I maybe crimp to the same, .381", bullet diameter/ COAL is 2.458" The data I found on Loaddata dot com, I think I might hit 1575 fps. Thoughts?

[Tar Heel]

Here we go again. This should be a sticky.

Please read this article on the Starline website. It will address all your questions. Bottom line: you need the longer brass for your Uberti.

https://www.starlinebrass.com/articles?id=2540

[Mk42gunner]

I use the longer length Starline brass in my Marlin 336CB. Using the larger diameter expander plug from the RCBS Cowboy die set and a .379" boolit, I have zero problems with just roll crimping with the RCBS die.

I don't think the Lee FCD is needed as often as Lee wants you to think. I do have one, mainly because I bought a whole caliber setup from an estate. Same reason I have a Redding competition seater which I do use.

Robert

[725]

I use Win brass for jacketed and Starline for cast. Solved all my tension issues.

[GSSP]

I'm sorry. I must have written my question very poorly. It has nothing to do with brass length or which die to expand or which die crimp with.

Let me try again.

Does anyone feel .007" neck tension is too much tenison or might I be better served with .004" neck tension?

Then...

Is crimping the mouth of the case to .392" SAAMI spec enough or should I go further, say .381", same diameter as the bullet.....or further......all the way to the bottom of the crimp groove?

Sorry for wording it so poorly the first time!

Alan

[Mk42gunner]

Alan, I think most of the confusion comes from the fact that there is just so much reported variation in .38-55 rifles and chambers.

I mean things like groove diameters being from .375-..383". That in itself is eight thousandths of an inch difference, there is only seven thousandths difference between the .270 Winchester and .280 Remington. Add in the confusion of two widely different case lengths for the same cartridge made for roughly 140 years, not to mention the very wide action strength of rifles chambered for it over the same time frame; it is somewhat understandable the differing opinions.

To answer your two questions: I personally feel that 0.007" is a bit too much tension. Your rifle may say differently though. Try two sets of loads one with each expander, it may make a big change, it may not. Only a paper target will tell.

Degree of crimp? I don't remember ever measuring the diameter of a crimp on a rifle cartridge. I usually just seat the projectile to the front of the crimp groove then adjust the crimp die down to turn in enough to brass to match the angle, without creating bulge below the crimp.

I have used a Lee FCD to crimp exactly one dummy .38-55 cartridge from W-W brass and a Barnes .377" JFP, so I'm really not an expert on its use.

Robert

[GSSP]

Robert,

Thank you for the "thought out reply". I'm the type to allow "paper" show me what works best. I will indeed try the larger expander, which should give me .004" neck tension and see what happens. Maybe even tomorrow.

Those who crimp cartridges such as 45 acp and 9mm, knowing the case headspaces on the mouth of the case set their crimp die to squeeze the mouth to .473" and .380", respectively; at least those are SAAMI specs.

Alan

[Char-Gar]

You want to be able to seat the bullet without deforming it. You want the bullet in loaded round with a moderate crimp to stay put, as it cycles through the rifle. The End!