30 carbine trim length questions


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16in50calNavalRifle
June 7, 2012, 05:41 PM
I know there are several experienced 30 carbine reloaders here, so I thought I'd ask a few questions, as I'm about to get a trimmer in anticipation of needing it for 30C reloads. (I have searched and read on this topic in the forum, but did not see anything precisely on-point)

I reloaded 300 once-fired factory cases (Aguilla, PPU, Remington) as my first actual reloads when I started last fall. With the exception of a 2 or 3 FTF, they all shot just fine (out of an Auto Ordnance reproduction and a 1943 Quality Hardware). I did not trim those cases the first time.

I also have 500 new unfired Lake City cases on hand that I picked up from PolyGun Bags.

My measurement of the (now) twice-fired cases shows an average case length of about 1.277, with only a very few much longer than that (they have not been resized); the Lake City all measures right at 1.286.

The Lyman 49th manual gives 1.286 as the "trim to" length, and cautions not to trim below that. The SAAMI specs, off their website, give a minimum case length of 1.290 and a maximum of 1.300.

1) Is it odd that the SAAMI spec minimum is larger than the Lyman trim-to number? And also odd in that case that the LC brass is right at 1.286? I realize my measurement and even trimming precision are probably too coarse to reliably see the .004 difference - but still .....

2) Stupid question - will I get a longer measure on my twice-fired brass AFTER I resize it?

3) According to the SAAMI spec, I can reload any case that measures up to 1.300 without trimming, correct?

4) Should I resize the LC brass and measure again, before proceeding? First time using unfired brass of any caliber.

I anticipate having to trim at some point, and so will continue my shopping for trimming equipment in any case (also expect to load 30-06 in the future, to feed my CMP Garand that is due some day soon ....). But if my experienced brass measures shy of 1.300 after resizing, it looks like I can go ahead and do my second batch of reloads without trimming, using the used brass and the new LC.

BTW, I stick strictly to duplicating original loads for the M1 carbine - 110g FMJ over 14-15g of H110 - with a hard CCI SRP.

Answers or advice appreciated.

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cfullgraf
June 7, 2012, 07:02 PM
Generally, cases will get longer after resizing. Upon firing, the case expands to fill the chamber, then springs back a little. But, the spring back is not back to the original size. There is a little inelastic deformation of the case upon firing. The sizing die squeezes the case back to "normal" size and the extra brass has to go somewhere.

You should not have to trim the new cases, even if you resize them. The new cases should be about the correct size, resizing them makes small corrections and tries up the mouths of the cases.

Swampman
June 7, 2012, 08:45 PM
I have .30 Carbine brass with five reloads on it that I've never trimmed, but I load it pretty light.
Generally, cases experience most of their growth during the resizing operation but the higher the pressure of the loads, the more the brass is worked, which leads to case stretching.
Are your "hard CCI primers" the #41 small rifle NATO primers? If so, they could be the reason for your ftf problem. When I first started loading .30 Carbine, I used the #41s and had a significant number of ftf's in both my 1944 Inland and a commercial Plainfield. As soon as I changed to Winchester primers, the problem went away.
I haven't had any slamfire problems with either primer.

USSR
June 7, 2012, 09:05 PM
16in50calNavalRifle,

It appears the trim-to length for the .30 Carbine is all over the map. Sierra lists it as 1.280" and I trim to that or a few thou shorter. Since the trim-to length is almost always .010" shorter than the maximum length, I trim them back when they reach 1.290". Always make your measurement after you have resized them. Hope that helps.

Don

FROGO207
June 7, 2012, 09:21 PM
I also use 1.290 as the max case length and can get 3 to 5 loadings before trimming most times depending on the brand of brass, but still I will start to check them after 3 loadings. This is one of the few straight walled rounds that I will bother to length check. This was from when I started loading the 30 Carbine and info was from Lee's Modern Reloading

16in50calNavalRifle
June 8, 2012, 02:36 AM
Thanks to all for your replies.

Swampman, no - I meant the standard CCI small rifle primers, not the military ones. I realized I might have left that misimpression after I posted. I meant "hard" as opposed to brands that are generally softer, like Federal (which I use in my revolver loads).

Well maybe I will load 20 that measure past 1.290 and see how they chamber and fire. I have just decapped/resized and measured a few cases (mixed brass), and they seem to be measuring between 1.283 and 1.295. I imagine there may be some penalty in accuracy/consistency from not having uniform lengths, but that's OK for now. If I'm getting rounds using 1.290+ that are reasonable to reload, and function acceptably, then I guess I can let it go for this cycle.

I assume that SAAMI max length is safe, and that it's mostly a question of function in individual carbines and desired accuracy/consistency.


I recognize that trimming is in my future for this caliber (and as I said I plan to reload for the Garand as well), so I will be equipping myself for trimming. Once I get my trimmer (right now I'm thinking the Forster Original, with the power adapter and the 3-in-1 cutter), I will be trimming to uniform length. I will have to decide what "my" max length is, I guess.

ArchAngelCD
June 8, 2012, 02:49 AM
I have found straight walled cases rarely need to be trimmed. In actuality the 30 Carbine is nothing but a straight walled magnum handgun round. The 30 Carbine and the .357 Magnum cases are the same exact length. (1.290")

gamestalker
June 8, 2012, 03:24 AM
Always do your measuring after having resized, as this is the correct time to meassure brass length. I assume you are using a dial caliper to measure? If so, your measurements should be dead on, so far as accuracy is concerned. About the worst for calipers I've seen has been .001", in terms of accuracy issues.

Your doing just fine, and it's good to hear of a new reloader takng the time to ensure they are doing everything correctly, and by the book. Keep up the attention to detail and procedure, and you'll have many years of enjoyment from this hobby.

GS

gamestalker
June 8, 2012, 03:26 AM
Always do your measuring after having resized, and prior to priming. This is the correct time to meassure brass length. I assume you are using a dial caliper to measure? If so, your measurements should be dead on, so far as accuracy is concerned. About the worst for calipers I've seen has been .001", in terms of accuracy issues.

Your doing just fine, and it's good to hear of a new reloader takng the time to ensure they are doing everything correctly, and by the book. Keep up the attention to detail and procedure, and you'll have many years of enjoyment from this hobby.

GS

cfullgraf
June 8, 2012, 07:41 AM
I have found straight walled cases rarely need to be trimmed. In actuality the 30 Carbine is nothing but a straight walled magnum handgun round. The 30 Carbine and the .357 Magnum cases are the same exact length. (1.290")

While 30 Carbine is similar to a straight walled hand gun case, it does headspace on the mouth and it does indeed stretch during successive firings and resizings. In that respect, it is not a typical straight walled round.

30 Carbine may not need to be trimmed as frequently as bottle neck rifle cases, but it should be measured and trimmed as needed.

(Side note, 30 carbine case walls are straight, just not parallel).

JohnM
June 8, 2012, 10:00 AM
The Carbine case has a lot more taper to it than most other straight wall cases.
The reason it wants to stretch so much I think.

USSR
June 8, 2012, 11:36 AM
Yes, it is a tapered case, hence it is suggested that you use some lube even with carbide dies. Only good use I've found for Hornady's One Stuck.

Don

JohnM
June 8, 2012, 11:43 AM
it is suggested that you use some lube even with carbide dies

Oh yeah! Lube 'em.
Makes sizing go SO much smoother even in carbides.
I have an RCBS steel set I like a lot better than the Lee carbide set.

cfullgraf
June 8, 2012, 12:28 PM
Only good use I've found for Hornady's One Stuck.


I concur.

16in50calNavalRifle
June 8, 2012, 08:09 PM
I lube the 30C - Imperial Sizing Wax.

Also use it with 9mm. I even will use a very small amount with .357 brass. Just makes it all smoother, and as I wipe down every reloaded round anyway as my final step after inspection and before storage, there's no real added work.

I have only carbide dies.

I've decided to just load up my 500 Lake City new cases, and order my trimming gear. So far measuring the resized once/twice-fired brass has produced only a small handful shorter than 1.900. So I'm just going to trim all of this brass. With the power adapter and the 3-in-1 cutter, figure it won't be a huge hassle.

Thanks for everyone's input. Real soon I'll be posting a sight/POI-related question about my 1943 Quality Hardware over on Rifle Country for you carbine enthusiasts.

rcmodel
June 8, 2012, 08:26 PM
I have never trimmed a .30 Carbine case in the 50 or so years I have loaded it.

If the bolt will still close on a sized case?
It is just perfectly right.

How do you suppose it got to be a fired case the first time if it wasn't?

rc

zxcvbob
June 8, 2012, 08:50 PM
I load .30 Carbine for a Ruger revolver. The cases do stretch, seemingly at random. The stretch doesn't show up until you resize them. You need to check them every time you reload them, after sizing; not all of them will need trimming but some of them may need a lot of trimming.

Use lube even with carbide dies. It's no fun sticking a case in the die.

JohnM
June 8, 2012, 09:10 PM
All I shoot carbine in is an old 3 screw BH and it is real fussy about length.

rcmodel
June 8, 2012, 09:14 PM
+1

If I shot .30 Carbine in a Ruger Blackhawk revolver, I would have to trim too.
But I don't.

My buddy did, and that thing gave both of us fits.

It had one chamber that sheared a 1/16" ring of brass of the case mouth and stuck it in the chamber at least once a shooting session.

rc

JohnM
June 8, 2012, 10:24 PM
:D Not too long ago I trimmed about 500 cases, some took only a touch, but it took me forever and by the time I got done I didn't want to look at another one.
There's another 1000 or so stuck away, but I think they can just stay there for a few years.

FROGO207
June 9, 2012, 07:04 AM
I have a pair of Ruger Blackhawks and also find them a pain to reload for. I used the emery paper and dowel trick to make the cylinders smooth and that right there helped out a lot with expansion as well as smoothing out the extraction a lot. Hardly ever a stuck case now even with max loads. As a side note I really like using it with lead bullets and Trail Boss. I can load it with such light recoil for 50' target that it is like shooting a .22 with the same accuracy as well.

zeke
June 9, 2012, 07:15 PM
The new Winchester loads owned and the RCBS carbide sized 30 carbine cases are not straight walled, or parralel (checked with straight edge of stainless calipers). They are slightly bottle necked. Am using lube and carbide sizer to load for carbine and Ruger. Trimmed alot of once fired range pickups to 1.280 for the carbine, and they work fine, especially fine with Hornady's fmj. The carbine has floating firing pin, and 1.280 trimmed to lenght is good precaution in my way of thinking. The trim length of 1.280 and harder primers causes un reliable ignition in the Ruger, but the softer Fed primers gave 100 %.

The chamber is large in the carbine, and the die takes alot of effort or sticks without lube. The first resizing seems to carry the most chance of stretching the case.

Remingtons lead rnsp give good chance of expansion in the carbine, but are not as accurate as Hdy fmj. The Ruger (a newer one) is extremely accurate.

Maj Dad
June 10, 2012, 08:05 PM
I didn't trim my carbine brass for years (a la rcmodel), but picked up a Lee trimmer pilot for it a few years back & sat down and trimmed the dickens out of all the empties. Never had a problem before, haven't had a problem since - I think the question may be moot in GI carbines, at least as far as my experience. I have a Lyman trimmer with all the "trimmings" but length repeatability with it is a pain for me, so I switched to Lee trimmers for all my calibers and am happy with them.
Just my 2 cents
:cool:

velocette
June 11, 2012, 09:16 AM
The trim to length problem with the .30 carbine is that the cartridge headspaces on the case mouth. If the case is too long, the bolt can go partially into battery. That is not lock up properly or fully. The results when that happens are not pretty. The rifle can and will fire out of battery.
Cases too short can get weak primer strikes and misfires, cases too long can fire out of battery which is a real nasty no no.
For all the information you may desire you can go here: http://forums.thecmp.org/showthread.php?t=2967&highlight=Reloading+case+trim

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