Sizing options for 38-55

[drumgool]

Well after waiting 5 months for my Winchester model 94 30/30 to get transformed
into a 38-55 it is finally here. I should have sluged the bore of my new barrel before I sent it off but forgot. I sluged it last night it messures .377 just a little resitence in the bore bushing through so I figure around .378-.379 final size.

To my knowledge Lee does not make a sizing die in this size . Is there any other ways to size a PP boolit . What are my options . Without having to wait weeks months on custom sizing dies.

[303Guy]

You might be better served to size the boolit to fit the throat. With just enough neck tension, the patched boolit should be able to chamber with just a slight resistance and extract easily but leaving a faint leade impression on the patch.

[Zeek]

Not So Fast, Yet Faster Still!

You might be better served to size the boolit to fit the throat. With just enough neck tension, the patched boolit should be able to chamber with just a slight resistance and extract easily but leaving a faint leade impression on the patch.
Good idea, there, but the problem is that the standard 38-55 HAS no cylinder throat, and HAS no step-transition (from chambermouth to throating). Instead, you have a 6 degree basic angle (12 degrees inclangle) cone from the chambermouth to the bore diameter. So whatever diameter you use will fit the throating. Mah!! The key is to take a soft-lead ball and hammer it into your muzzle with a soft mallet, then eject it from the rear and use a set of micrometers to measure the groove diameter. Order a custom push-thru die from Lee that is 0.001" OVER that groove diameter (good for PPCBoos & will work on GCCBoos too) or that is right on groove diameter, for PPCBoos only. Custom Lee dies: http://www.leeprecision.com/html/catalog/custom.html#CUSTOMLUBESIZE

WARNING: if your groove diameter is over 0.378", then your standard 0.395" diameter chambermouth diameter will not let you chamber rounds with a groove-diameter-matching bullet diameter with available thicker-necked-and-WAAAY-too short brass . . . so, you are forced to switch to the FABULOUS new Starline 2.125" long 38-55 brass, which has a neckwall thickness just over seven thousandths! (Hint: its the way to go, Dude!)

Paper patch to ~0.010" over the groove diameter, then give the dried-patch a touch of car wax and run it through the sizer. The resulting hard-sized PPatch is tough and you'll like its performance in your rifle. Adjust the forward end of your PPatch to give you light resistance to chambering (like 303Guy says) when your LOA is within spec for your Marlin. Alternatively, have Mic McPherson "lengthen" your Marlin's action so that it will handle cartridges as long as 2.73" (up from 2.59" usually). My Marlin Cowboy 38-55 has a groove diameter of 0.381+, so I was dead in the water until Starline came out with their lovely new proper-length thin-neckwall brass (yes, you COULD turn the neckwall of Winchester brass thinner, but cutting to 0.007 is a real trick and the case's taper poses problems too).

The 38-55 in the strong Marlin action is capable of exceeding 2000 fps with a 250gr PPCBoo . . . a WHOOOOLE new ball game, compared to the chambering's humble initial performance. Stay within normal upper pressure limits with that Winchester of 35 Kpsi (remember, they upgraded their action considerably for the 375 Winchester, which uses loads like the Marlin can take as-is).
Enjoy, now, y'hear?!
Zeek

[303Guy]

... the problem is that the standard 38-55 HAS no cylinder throat, and HAS no step-transition (from chambermouth to throating).I wondered about that. Would it be sacralidge to hone the mouth are of the chamber to take the thicker brass? Not suggesting it it, just wondering.


The 38-55 in the strong Marlin action is capable of exceeding 2000 fps with a 250gr PPCBoo ...That's pretty healthy! That would be enough recoil for me for comfort. (I've gone off recoil!):mrgreen:

Something else I am wondering about and that is boolit upset. I've had it where the bore-ride section of the boolit only lightly, if at all, touched the bore, yet the fired boolit had rifling impressions right up to the ogive. And considering that the black powder folks patch to bore diameter ....

[Zeek]

Dear 303Guy:
Many folks have had that ream-out-the-chamber-neck-a-bit idea, but it has worked poorly for most.
I was speaking of using WW+Sn alloy (although I didn't say that), so the principal upset is in the rear of the PPCBoo core. Bullets for 38-55 have no bore-riding nose section, just bands and point.
Zeek

[303Guy]

Thanks for that info. Perish the thought!:mrgreen:

Is that established the the principal expansion is at the base of the boolit? I would have expected it to be so but observation (which are frought with error and misinterpretations) seem to indicate that obturation extends quite far up the shank. Perhaps this is because after the 'principal' upset, the boolit is supported by the bore and over the time od passage, the upset migrates forward. So, with a careful selection of powder, charge and boolit weight, one should hope to delay that 'principal' upset until the base of the boolit clears the leade or at least start of the leade. (Easier said than done!)

I am recovering boolits which give the impressiion that the area in front of the mouth has expanded more than the base. That could be a misinterpretation due to the nose expanding on impact. I need a different catch medium.

Well, drumgool, I do hope to hear of your progress soon. Things like this get my interest! Besides, I enjoy success stories.:drinks:

[Nrut]

Zeek,
What powder(s) and what boolit are you using in your Marlin CB to get that kind of vel.?
Thanks
:-)

[Zeek]

Is that established the the principal expansion is at the base of the boolit? I would have expected it to be so but observation (which are frought with error and misinterpretations) seem to indicate that obturation extends quite far up the shank. Perhaps this is because after the 'principal' upset, the boolit is supported by the bore and over the time od passage, the upset migrates forward.
Yes. The powder blow is the hammer and the remaining unaccellerated mass ahead of any given point on the PPCBoo core is the anvil. This "anvil" gets lighter the further you move forward on the CBoo-core, so provides less upset/obturation-producing resistance toward the nose than at points toward the rear.


So, with a careful selection of powder, charge and boolit weight, one should hope to delay that 'principal' upset until the base of the boolit clears the leade or at least start of the leade. (Easier said than done!)

Get QuickLOAD software and you'll see. Most rifle powders peak out with a bullet travel of at least one inch (some are at up to well over 2") of bullet travel. For powders designed for use in rifle cartridges, AA-2495 gives a peak that is FAR further forward than any other powder of comparable "speed" (more like IMR-4350). That is why AA-2495 is such a neat CBoo and PPCBoo propellant. I know that this sounds crazy, but a powder's burn "speed" is not always inversely related to its peak pressure location, for a given max pressure in a given cartridge. Get QuickLOAD and play with it and you'll see what I mean.


I am recovering boolits which give the impressiion that the area in front of the mouth has expanded more than the base. That could be a misinterpretation due to the nose expanding on impact. I need a different catch medium.
The rear is the first to begin expanding in the barrel, followed soon thereafter by progressively more forward locations on the PPCBoo core, but no location can get any larger than the barrel I.D. (let's ignore, for now, that the barrel I.D. expands in response to this pressure). Once the CBoo's expansion crushes the PPatch and presses the PP/CBoo assembly radially against the rifling, that part of the bullet functions to seal (against gas blowby) and give torque-up to get the CB spinning . . . . typically, it exits at between 100,000 and 200,000 rpm, after a very fast spin-up.

At some point, well away from the bullet's base, there is a balance point where there is not enough mass ahead of that location to act as a big enough "anvil" to get that portion expanded out to fill the rifling grooves (for a given bullet weight and degree of acceleration). All locations forward of that point expand even less.

That has nothing to do with the point's expansion when it hits the target.

At least, that is my mental model of how it works.
Regards, Zeek

[303Guy]

Yup. That's pretty much exactly my mental model too. Thanks.

[drumgool]

Well I orderd some sizing dies from lee 3 - 6 weeks away. It seems like I will never get this rifle up and going. Been about 9 months since first purchased the otiginal 30-30 rifle. Found a forarm that fits the barrel , been sanding & fitting this weekend it is darker than my butsock
will have to try & get both to match. Orderd reloading dies and having to wait on starline brass avalibility. I waited this long I quess a little longer wont hurt.

You guys sure give a man a lot to think about in when you ansew a post. Great info. I have had good and easy sucess PP my 30-30 . Sounds like this 38-55 will be a little more of a chalenge . Thanks For the info.

[coyotebait]

Zeek
Could you clarify a bit on your statement about reaming the 38-55 chamber neck? I have two 38-55 rifles with tight chamber necks in relation to barrel groove size and have considered reaming the chamber necks in order to use a fatter boolit to better fit the groove.
I don't paper patch so if you consider this a hijack I will move the question to a new thread.
coyotebait

[drumgool]

Coyoteebait
I don't consider this a hijack . The more info we learn about this caliber the better off we will be.

[RBak]

I am recovering boolits which give the impressiion that the area in front of the mouth has expanded more than the base. That could be a misinterpretation due to the nose expanding on impact.

303 Guy.... Good point!
Probably not a real important point, but I have been "cyphering" on this very same subject for several years now...ain't no further now than I was in the early days.

Shooting a looong bullet like the 358009 in my Whelen, I have recovered and mic'd many boolits with "what appeared to be" three, yep 3 obturation points!
One at the base just at the GC, one at the front, which I can always contributed to impact, and one a little less than half-way the length....now, this does not always happen, and it's sometimes more remarkable than other times, but it has happen enough to catch my attention and make me think, or wonder why the heck that is.

Can't see that it bothers anything, and I can't always depend on finding this after recovering a range session.

Still yet, I have been seeing this long enough to just accept the fact that "that's just the way it is" because no one seems to have an answer for it, and I guess I ain't smart enough to reason it out, not that it needs reasoning.

Russ...

[303Guy]

Well, my molds form concentric creases that almost look like they're intentional. I have one boolit that had one of these crease rings at the case mouth. It looks as though the metal upset on this junction and that the boolit actually twisted on this plain as the rifling impression ahead of it was a bit widended while behind it not. The two thrust faces were in line.

This swelling, just in front of the case mouth point is preserved by the compression of the patch. So, I'm not alone! Oh, these concentric crease rings get accentuated by the patch on firing.

The concentric crease rings are due to my hollow point nose pour arrangement and a too cool a mold.

[Zeek]

Zeek,
What powder(s) and what boolit are you using in your Marlin CB to get that kind of vel.?
Thanks :-)
PPCBoo: Mountain Mould 0.368-250 PP (0.925"-long smooth-sided CBoo w/GC shank bare & 0.27" diam. meplat, 12 Bh {WW+Sn alloy}; 2X28# PPatch sized in 0.381" die); this is a K-BOWM type bullet design [see article on these that is linked at the bottom of the NEI opening web page { http://www.neihandtools.com/ }]
Charge: 41.5gr of AA-2495 swirl-charged (better than a drop tube!) takes the nominally 111+% charge density down to a doable ~105% (compressed charge), seated to a 2.65" LOA (rifle action "lengthened" by Mic McPherson to handle an LOA of up to 2.73")
Case: 2.125" long Starline brass with very thin neckwall (0.007+"), Remington 2 1/2 primer
Gives: 2090 fps @ ~30 Kpsi (nominal max allowable is ~35 Kpsi); the peak pressure is at the 1.54" point of bullet travel; muzzle pressure is 5 Kpsi.

Damn but I love that load. I hit a big jackrabbit with it once at a bit over 100 yards and it just flat came apart. That 28 pound paper PPatch makes for a really neat snowfall too. If I had it to do over again, I'd order that MM mould to cast 0.373" instead of the 0.368", but you won't see me crying about the way it is. Once you realize HOW to satisfy these large-groove-diameter rifles (i.e. use Starline brass so you can actually chamber a proper-diameter CBoo or PPCBoo), then you face the other Big-Ugly: WHERE am I going to get a CBoo that casts 0.381+"?! Well, NEI has some, but, really PPatching is the key.

With the patched-way-over-&-sized-down-to-.381+" PPCBoos plus those lovely Starline cases, this rifle is a real joy to play with . . . . just keeps on Really-Big-WHUMP'n-Em in there. Yee haw!
Regards, Zeek

[drumgool]

Done a chamber cast tonight with cerrosafe. Best I can tell chamber mouth is .396
grove dia. .380 It was hard to get the bore dia. I think its .376 If I got an accurate measure . I will do it again tomorrow night and compare .

It was hard to get the case lenth but I think I can use the longer brass 2.125 I have a couple of winchester brass I pick up off the range they measure 2.080 they seem just a little short. Neck thickness is .009 so with a .381 pp boolit that would put me at .399 . So Starline brass only. What is the optimal clearence of a lloaded round at the chamber mouth?

Well I'm sloley but surley moving forward with this project

[Nrut]

Zeek,
Thank's for your detailed reply..
My MarlinCB has the same groove dia. as yours.. I have a had it for going on 6 years but gave up on it and the NEF Target in 38-55 which also has a .381+ groove as I would get inconsistent results..
I figured some day on getting reamer made up to ream out the chamber neck to accommodate .383" boolits..
Late last fall I got to thinking pure Pb PP sized .379" to chamber might bump up with smokeless and decided I would try that before I ordered a reamer..
I did buy some Starline long brass 2 years ago and it works fine with GG boolits in my Uberti Low Wall 38-55 but the Uberti has a .380" groove..
I didn't try Marlin & NEF with Starline as other rifles accumulated and were demanding attention...
Anyway I looks like I should check my bore dia. on the Marlin and NEF order a push thru sizer and PP the 38-55.. My lightest cast boolit for the 38-55 is 260grs so I'll start below your listed load.. Op's just remembered that I have a 233gr. one also
I really like the Marlin CB as a rifle and if I can get the same results as you then it'll end up being a keeper.. 250 grs at 2000fps should be a killer..

Two things..
~~On the McPherson mod. to your rifle, did he re-cut your throat for a longer OAL along with modifying the lifter to feed a longer OAL round?
~~I have seen the swirl tech. explained I believe in a McPherson article in Precision Shooting or The Accurate Rifle long ago.. You won't happen to remember which issue it was in would you? If not I'll just start digging in my stack when I get started on this project..
Thanks again,
Mic

[Zeek]

Zeek,
Two things..
~~On the McPherson mod. to your rifle, did he re-cut your throat for a longer OAL along with modifying the lifter to feed a longer OAL round?
NO! He fiddled with the inner parts and it will now feed a cartridge up to 2.73" long.


~~I have seen the swirl tech. explained I believe in a McPherson article in Precision Shooting or The Accurate Rifle long ago.. You won't happen to remember which issue it was in would you? If not I'll just start digging in my stack when I get started on this project.
No need for that. Just put your funnel onto your casemouth and then use your scale-pan to pour your powder charge slowly parallel to the top rim of the funnel. This causes the grains to "swirl" (follow a helical pattern) as they move down to the mouth of the funnel's tube. This lets each grain fall into the case by itself, in sequence, thereby giving it time to settle in before getting locked in place by the next grains. The result works better than even a long drop tube to get the least volume for a given charge weight. It even works on spherical powder grains.
Regards, Zeek