.30 Carbine Trim Size

[ncbearman]

Any M1 guys out there do this regularly? If so what is your favorite trim to size. Do I need to do a chamber slug to find out mine?
Russ

[Artful]

Trim to 1.280 max 1.290 - get a case gauge or load in batches and measure samples.
I've used cast bullets as well as jacketed. Have not tried plated. You'll want to taper crimp.
No leading for mine, BUT.... Some carbines do not like lead bullets and will lead up the gas system.
I had a friends that did that out of about 30 rounds that were cast bullets.
It was so bad that it took us several hours to clean the piston chamber.
Most carbines like cast, but a few really hate them.
IMR 4227 seems to be the most liked powder and if you adjust the tension of the front barrel band screw you can get some amazing accuracy out of a carbine.

http://www.odcmp.com/Training/CR/CarbineNotes.pdf

[jonk]

While a chamber cast would give you your exact trim to length, I just go with whatever the Lee gauge trims it to, no issues. Which is in point of fact right around 1.280. I also have shot both cast and jacketed; I like WC 820 as it is pulldown M1 carbine powder, similar to AA #9, perhaps a wee bit faster depending on lot.

[zomby woof]

I trim to 1.286". I check and trim as needed after each firing.

[whelenshooter]

I trim to whatever the Lee trimmer is built to and then check each time they're being reloaded to make sure they're still under the max.

[williamwaco]

They do not need to match the chamber exactly.
They must not be longer than the chamber.
Shorter is fine.
All the same length is the goal

[fcvan]

The only gun that gives me fits with case length is the Ruger BlackHawk pistol. I made up a bunch of rounds and fired through several carbines with no problems. Then I tried to shoot some through the RBH and they were a no go. I bought the Lee trimmer and problem is solved. Now I'm loading up a SAECO 321 which is a plain based boolit, powder coated black, and sized to .309. They look and shoot great!

[cwheel]

One thing that hasn't been addressed why the uniform trim is so important. Carbine is best loaded with a taper crimp die as a final operation by itself. Just a lite crimp of .003-.004 will do. If all of the cases are trimmed to plus, or minus .001, then the crimp will be uniform with the crimp die remaining in the same position. The more uniform pressure generated by a lot of reloads generally adds to the accuracy of the batch of reloads. Carbine cases need to not only be trimmed every loading, but very uniform to keep reloads accurate. This for sure is not the only factor, but sure adds to a good reload. One other thing, the crimp uniformity seams to matter more than mixed lots of brass and variable case volumes, you would think it would be the other way around ??
Chris

[Larry Gibson]

I've loaded and shot a bajillian 30 carbine cartridges through many M1 & M2 carbines both jacketed and cast, mostly cast. I made a max case gauge and gauge new/fired cases when I get them. I only trim those too long. I have never since gauged or trimmed the cases I load and shoot. Many have been shot multiple times with full power loads. They just do not increase in length.

Larry Gibson

[ncbearman]

Larry, what is your preferred case length?

[Larry Gibson]

Be late tonight before I can measure the gauge.

Larry Gibson

[cwheel]

Don't know what your shooting yours in Larry. Mine fired in either of my old Winchesters end up long after just one firing ?? Oversize chambers?? Nothing unusual about the loading, 12 gr of 2400 under a lyman 311359BV with gas check ?? Long each shot, enough to trim after resizing. Don't think M2 makes any difference, chamber should be the same.
Chris

[timspawn]

I just started loading for this round. I have yet to find a case that needed trimming. They have all been short.

[jcwit]

Mine need to be trimmed after 3 to 4 firings.

Its my understanding that its the resizing that lengthens the case.

[Larry Gibson]

Measured my gauge and it is the "Trim to Length" suggested by Lyman at 1.286. I measure the cases after sizing as that does lengthen them. Then after firing and before sizing if you measure again you'll find they do "shrink" a couple thou on firing due to the tapered case/chambers and the expansion back in web and main body area. So be sure to measure for max oal after sizing. I originally sized with a steel RCBS sizer, then went to a CH Sizer (it sized the "neck" straight which was better for the 311359) and finally to the Lee carbide sizer. Sorry but I find the 30 carbine just does not need trimming, same with 45 ACP, 9mm etc. Perhaps I'm just lucky.........

Larry Gibson

[Firehand]

The notes on reloading on the CMP site suggest trimming to minimum length, which is what I do just to be on the safe side.

I've used the X-Treme plated bullets with good results, get best accuracy with a bit lighter load than with ball. No problems shooting cast, though after a hundred rounds or so did have a bit of fouling built up on the piston.

[Ed in North Texas]

One thing that hasn't been addressed why the uniform trim is so important. Carbine is best loaded with a taper crimp die as a final operation by itself. Just a lite crimp of .003-.004 will do. If all of the cases are trimmed to plus, or minus .001, then the crimp will be uniform with the crimp die remaining in the same position. The more uniform pressure generated by a lot of reloads generally adds to the accuracy of the batch of reloads. Carbine cases need to not only be trimmed every loading, but very uniform to keep reloads accurate. This for sure is not the only factor, but sure adds to a good reload. One other thing, the crimp uniformity seams to matter more than mixed lots of brass and variable case volumes, you would think it would be the other way around ??
Chris

The taper crimp has been recommended over the years for other than semi-auto weapons because the case length doesn't matter as much as it does with a roll crimp, where every case must be the same length in order to get the same crimp in each case. While exactly the same length cases will assure exactly the same degree of crimp, those cases which are a little shorter will still be sufficiently crimped. We should strive for the best accuracy we can get, but the .30 Carbine isn't exactly a NM weapon or round.

[leadman]

A roll crimp won't due in the carbine since it headspaces on the case mouth. I have one carbine that will shoot moa at 100 yards with the Sierra 110gr Hollowpoint.
Both my carbines shoot cast very well, hard to tell them apart from the Garand on paper. WC820 works great along with 296.

[ncbearman]

Well since I have started this thread I have had some good results. I have probably shot 700 rounds since then. The recipe I have settled on is a 130gr MiHec 311410 GC over 11.5gr of 4227 1.600 OAL, NO CRIMP, just enough to take the bell out of the case from seating the boolit and chamber smoothly. I had some old WWII loads for the carbine and noticed they were not crimped so I gave it a try. As far as trimming, I have surmised that anything over 1.285 I trim. But once I do thats it. I got very little leading on the piston and what was there cleaned up easily. 3" circles at about 50 yards is what I am getting. Ringing the steel every shot. Here is a pic dancingbear put on the mould thread of the same mould I have and a pic of my Carbine.

http://castboolits.gunloads.com/show...rass-Cramer-HP

Attachment 87843

Attachment 87844

footnote;

I know 50 yards isn't very far, but it's on my property and I don't have to pay or travel to shoot.
Russ

[Ed in North Texas]

snip
I had some old WWII loads for the carbine and noticed they were not crimped so I gave it a try.

snip

Russ

Russ, are you sure there is no crimp on that ammo? All carbine ammo, and any other cartridge which headspaces on the mouth of the case (most semi-auto pistol ammo), should be taper crimped. Taper crimp simply presses all around the case, pushing it against the projectile without changing the profile of the case or projectile. So if you were looking for a roll crimp it would look like it wasn't crimped. Two other taper crimped cartridges you should have seen lots of are the .45 ACP and 9x19mm.