45 ACP Headspace on Shell or Bullet ?

Some barrel throats are shorter than others, Springfield seems to run short. Disregard the book OAL and seat so the shoulder of the bullet is no more than .030" past the case mouth. This should solve the plunk test. Also, seat and taper crimp in separate steps, if you don't already.

The headspace is determined by where the mouth of the case contacts the step in the chamber. What you are encountering is the shoulder of the bullet contacting the leade of the chamber, which simply means the bullet is seated too far out for YOUR chamber.

Some chambers have shorter leades than others, so you have to load your ammunition for that chamber. Seat the bullet so there is just a couple thousandths of the shoulder above the case mouth and see if that solves your problem. If it does, and the rounds will still feed from the magazine reliably, then work up your load with that OAL, whatever it turns out to be.

Hope this helps.

Fred

Forget any "OAL" specs entirely. Load so you have about a dime's width of the wadcutter shoulder showing above the case mouth -- no more.

I have loaded cast .45 ACP SWCs to chamber with the shoulder against the lands for some decades now.

I have gotten lazy and seat them all to suit my shortest chamber of late, though.
About .93" to the shoulder instead of MEhavey's .94".

Shorter is good too (note lefthand 185gr bullet)
"Whatever works"

My 45 ACP Springfield

Had a short chamber and with my lead lead bullets, I would have chambering problems. Same rounds would drop into my S&W 625-8 revolvers without issue.
I had a gunsmith open up the headspace which helped.
I ended up buying and fitting a KART barrel which has been very nice.
To much head space will allow primers to protrude and pop out. I have read that some GI 1911's actually headspaced on the extractor due to generous tolerances. Not a problem with crimped primer pockets.

when I loaded for my 45 acp Kimber and S & W 1911's the sharp edge was about .025 above the case mouth. I traded those guns off for a Range Officer and found oal length for the other two guns was too long for the Range Officer. the oal length ended up with the sharp edge of the bullet being even with the case mouth. it also has a tight chamber as I found out if the cast bullet is over .452 there will be problems there as well. I size all of the cast bullets through a .452 Lee bullets sizer regardless of what the diameter says on the box. both of those problems are now solved.

jacketed bullets have never been a problem

A 45 will never headspace on the bullet. The diameter of the bullet is smaller than the case by roughly 20 thou.
Headspace checks are not determined by plunking either. Plunking is to see if your loaded cartridge fits the chamber. If it doesn't the taper crimp is usually the issue.
"...Hodgdon web site shows 1.225"..." For a LSWC. 1.200" for an RN. Don't worry too much about OAL. Too short is more of an issue.
My old Lyman book says 1.275" is max OAL. Been using that myself for eons.

Like stated above. I have to load 2 batches of different OALs because my 1911 likes them long but my XDM likes them short.

A 45 will never headspace on the bullet.

Click to expand...

Never say never, I have loaded thousands that do.
They don't headspace with the bullet against the chamber mouth, that diameter is irrelevant; they headspace with the SWC shoulder against the origin of the rifling.

Hodgdon OAL numbers are just weird.
The SAAMI maximum can cause trouble if you are not loading the elliptical nosed hardball bullet, too.

45 acp col

Jim Watson +1 How i do it for slow fire cast lead rounds. Depends on how the barrel is chambered. I learned it from an old NRA reprint on the 45 acp years ago. [/URL][/IMG]

Mike44 said:

KP321 - thank you for your helpful reply. I use a Lee 4 die set and do seat and taper crimp seperately

Click to expand...

There is one caveat about the Lee Factory Crimp Die (FCD). Particularly with lead lead bullets and exacerbated with thick-walled brass, the Post-sizing ring has the POTENTIAL to cause the bullet to be undersized for your bore.

Some people go so far as to knock the post-sizing ring out of the die to avoid this. (But getting it back in is probably impossible).

With undersized bullets, leading may occur and accuracy and velocity may suffer.

Like I said, there is the potential for these problems, which has not stopped me from using the 4-die set for my 45 ACP shooting with lead bullets. I just measure a previously loaded and pulled bullet. No problems for me so far, but if I ever get a 45 ACP with oversized barrel bore or overly thick brass, it could happen.

Lost Sheep

(edit) There is also the question of the post-sizing causing a reduction in neck tension (this is also primarily exhibited in lead bullets), but that is another subject.

Some barrel throats are shorter than others, Springfield seems to run short. Disregard the book OAL and seat so the shoulder of the bullet is no more than .030" past the case mouth. This should solve the plunk test. Also, seat and taper crimp in separate steps, if you don't already.

Click to expand...

+1

How?

They don't headspace with the bullet against the chamber mouth, that diameter is irrelevant; they headspace with the SWC shoulder against the origin of the rifling.

Click to expand...

Not disagreeing ....this is a search for knowledge....how do you know that is what happens? How did you measure that?
When the cartridge is head spaced as described, where is the mouth of the case in relation to the headspace step in the barrel?
Pete

Using an auto pistol barrel find a MAX O.A.L with your bullet

Pete D. See Walkalong's thread http://www.thehighroad.org/showthread.php?t=506678

Mike44 said:

I settled on a OAL of 1.240 after cycling dummy rounds. I set the Lee FCD to crimp to .471 and checked that the bullets were not getting squeezed to a smaller diameter. I worked up a load using AutoComp. All of the rounds (75) cycled fine and shot well. I did get one crushed shell on eject, so I will up the load a little so see if that helps. I found that the barrel was easy to clean up with two passes with a bronze brush. I really like the clean holes in the targets. After I use up my supply of plated 45ACP bullets, I am switching to the Missouri Bullet Bullseye #1 200gr. LSWC. Thanks to everyone for the helpful information.

Click to expand...

It sounds like you did everything correctly and you have a good load.

What are the charge weights of AutoComp you are using? What was the original charge and the upped charge weight? I have not tried Autocomp yet, do you like it? How accurate is AutoComp compared to the powder you were using?

You CAN, but you SHOULDN'T

Headspacing for your purposes is to hold the cartridge up against the breechface so the firing pin strike will ignite the primer, right?

You can accomplish that by the bullet engaging the rifling, But this is not reliable if you happen to fire your cartridges in a different gun or a different barrel or if your rifling eventually gets a little worn or if your bullets' ogive differs one to another.

You can accomplish that by the extractor engaging the extractor groove. People have even been able to fire 380ACP and 9mm Makarov in a 9mm Parabellum chamber. I imagine this would allow 45GAP to be fired in a 45ACP chamber in the same way. But this is not reliable if you have a slightly thinner rim or a little wear on your extractor.

SAAMI specs suggest the proper way to headspace is on the case mouth.

Lost Sheep

p.s. Many rifle shooters (whose cartridges headspace on the shoulder) set their bullets to just "kiss" the rifling (seeking superior accuracy), but they DON'T use the bullet to headspace.

Mike44 said:

Missouri Bullet (Bullseye #1, .452 diameter) to give SWC bullets a try in my 45ACP Range Officer. Most suggestions I have seen are for a OAL of 1.250" while the Hodgdon web site shows 1.225" for OAL. With either seating depth, the cartridge is headspacing on the bearing area of the bullet rather than the mouth of the shell.

Click to expand...

My Sig 1911 barrel has almost no leade with sharp angled/quick start of rifling (left picture) as compared to 40S&W Lone Wolf barrel with longer leade and slower start of rifling (right picture). With the same Missouri 200 gr SWC (Bullseye #1), my max OAL/COL is 1.245". Any longer and the shoulder of the bullet/bearing surface will hit the start of rifling.

Sig 1911 barrel with almost no leade and Lone Wolf barrel with longer leade (white arrow)

Mike44 said:

Success!
I settled on a OAL of 1.240 after cycling dummy rounds.

Click to expand...

Glad things worked out.