What is the "split case" method?

[stubbicatt]

I read Jeff Cochran article and there was a reference to split case method. Can anybody tell me what this is? Tried the search function and saw other references to it, but I was unable to find an explanation.

Thanks in advance.

Regards,
Stubb

 

[M-61]

Are you referring to 'splitting a case' to determine the length to the lands? Cutting slots in the neck with a saw to insert a bullet, chamber, extract and measure?

 

[stubbicatt]

Are you referring to 'splitting a case' to determine the length to the lands? Cutting slots in the neck with a saw to insert a bullet, chamber, extract and measure?

I don't know. The text in the article is talking about reloading, and here it is:

"I seat the bullets about .005" to .010" over the 'touch' length when using the split-case method."

Thanks if you can explain it. I'm still trying to understand many vocabulary type things.

 

[nosualc]

http://www.youtube.com/watch?v=J1yBCarMgZQ

-nosualc

 

[M-61]

From that excerpt it seems to me he is 'slicing slits' in the neck of a sacrificial case, inserting a bullet, chambering the round, and then after extracting the cartridge measures the OAL. That would give him the measurement overall, for his particular rifle,of the distance from the closed face of the bolt to where the bullet touches the lands. If he desires to 'jam', then he would add (in this case) the number of thousandths he wishes to jam to the overall length. In theory the bullet, once it touches the rifling, will be pushed backwards into the case resulting in an over all length of a cartridge to stat with. Is it the most scientific was to do this. No.... 3 slices in the neck usually allow the bullet to move without getting stuck is the rifling. Remember that number is for HIS rifle, with THAT bullet, in That case. There are a number of tools that can do this and the overall cost is not high. There are any number of folks on this site who can explain it better than I have and I am sure you'll get a few more responses. Of coarse all that I have said is based on whether I have understood what the original writer was talking about.

 

[Nvreloader]

It is referring to the split neck method,

Take a sized case, then using a .010" width blade, (Dremel cutoff blades works OK) cut down the neck full length to junction of the neck/shoulder angle, clean burrs inside/outside of the cut.

To use, make sure the case will hold a bullet without falling out of the case, insert bullet to LONGER than throat length, carefully slide the case into the chamber, lock down the bolt.

The bullet will contact the throat taper in the bbl, and then slide back to properly seat into the case when fully chambered, (with the proper tension on the neck slit, too loose and the bullet will pull away from the case, if too loose, then lightly pinch the case neck together to provide proper tension to hold the bullet).

Open bolt and carefully remove case, don't let case/bullet slide and eject from chamber, hold with fingers until the action is fully open, carefully measure/record this measurement, using anyone of several different tools available.

This will give you a good starting place for setting bullet seating depth. YMMV

Tia,
Don

 

[dryhumor]

Pic of the split case.

Pic of the drilled out primer pocket to allow push back of the bullet

 

[stubbicatt]

Aha! Thanks. That makes sense.

 

[dryhumor]

Forgot to add, mark around the ogive area of the bullet with a sharpie. You'll see it seat into the lands. I try to mark evenly at the split/case mouth junction to see the push into the case when chambering.

I like to slit only one side, to allow a firm hold of the bullet. I mark and chamber several times, and measure.

AND, start with a fully prepped and trimmed to length case that you will be using.

 

[DennisH]

The below article is about the best I know of explaining the "split case" method.

http://www.larrywillis.com/OAL.html

Below is my procedure when chambering a barrel and I want the throat cut to an exact point matching the bullet I am shooting. This also assures me exactly where my bullet is seated in the neck. I personally don't like any portion of the boat-tail seated in the case (shoulder area).

I drill a 1/8th hole about in the middle of the neck (FL sized cases). I put a fine bit on my dremel and cut a slot straight down about 1/2 way into the shoulder. I mark the bullet where the boat-tail starts on the bullet with a red sharpie. I seat the bullet in the brass exactly where I want it (I make 3 of these) and send it to the gunsmith chambering my barrels.

This leaves the upper portion of my neck intact and the bullet is secure. You cannot pull it out with your fingers.

Make sure the person chambering your barrel knows exactly what you are doing. I tell mine to cut the throat exactly to match the dummy rounds I sent, and explain there is no leadway.

JMO, Dennis

 

[Martin52]

The spliced neck method works well, but if you don't have a Dremel you can achieve a similar outcome without cutting the case neck by using a Lee Collet die to size the neck down just enough to hold the bullet. The rest of the process is the same as described above.

Martin

 

[gotcha]

actually, a "kiss" touch to the case mouth with a standard neck die will give enough tension to hold a bullet also. Though I prefer the once or twice split neck method.