Crimping .45ACP

[LoopyLenny]

Quick question about crimping .45ACP.

My reloading manual says not to crimp any rimless automatic cartridges such as .45ACP that headspace on the case mouth. However, it seems that putting a taper crimp on is a common practice.

I haven't been crimping my rounds and haven't had any issues with bullets being pushed into the case.

Should I start taper crimping? Why does my manual say to never do it yet it seems to be common practice?

[RickB]

Crimping does not, or, should not be relied upon to, prevent bullets from being pushed into the case. I have never seen or heard advice against taper crimping auto pistol rounds. Taper crimp merely irons out the bell applied prior to bullet seating. If I don't apply a small taper crimp, my rounds won't chamber. If yours do, you are probably OK. Most people crimp to a specific case mouth measurement, with .470" apparently being the most popular.

[Jackhammer]

If you flare your cases, you should at least iron out the flare with the crimping tool like RickB suggests.
I don't flare or crimp (jacketed bullets) with my auto pistol rounds.

[nking]

Originally Posted by RickB

Crimping does not, or, should not be relied upon to, prevent bullets from being pushed into the case. I have never seen or heard advice against taper crimping auto pistol rounds. Taper crimp merely irons out the bell applied prior to bullet seating. If I don't apply a small taper crimp, my rounds won't chamber. If yours do, you are probably OK. Most people crimp to a specific case mouth measurement, with .470" apparently being the most popular.

YES! Finally somebody that gets it. Everybody I talk to thinks I'm crazy when I tell them that crimping really isn't what holds the bullet.

I taper crimp slightly. The books tell people that so they don't smash the case mouth into the bullet. A little is all that's needed.


Nate

[herd48]

nking- there are threads on here continuously with people that don't get. So many think that crimping is the thing that prevents setback. There is a thread concerning 223 loading where this was an issue recently. Some refused to accept the fact that proper resizing prevents setback. There are a lot of new reloaders on this forum. And a lot of inaccurate info being offered. This forum has undergone a dramatic change since Obama. We should have a sticky warning it's so prevalent

[kimberguy2004]

Bill Wilson's recomendation of .468 is what I use and it works for me, but a lot of guys use .470 with good results. Anything close will work, you just need to make sure you are removing all of the flare from the case.
Proper sizing is in fact what prevents setback. Run your die all the way to the shell plate, lock itand then LEAVE IT ALONE. There's no problem that can be fixed or compensated for by changing the adjustment of the sizing die. If you are adjusted correctly and still have setback, try some different brass.. Some of that stuff out there not may not size correctly, AMERC being the most notorious..

[mark2734]

Like anything else saying NEVER or ALWAYS is miss leading.

For the most part neck tension is what holds rounds in place with common handgun loads.

Rifle loads used in semi/full auto weapons, do need to be crimped to prevent setback. Most mil-spc FMJ bullets do have a crimp groove just for that purpose.

When you move up to very heavy recoil handgun and rifle rounds the need for crimp is to prevent the bullet from jumping out of the case, common on super heavy magnum handgun rounds.

Smaller caliber rifle rounds, say .270 or 7mm Mauser, do not generate enough recoil to cause issues.

Bottom line is while there may be general guidelines a reloader needs to study and research each caliber they load.

[wilkersk]

This is how I FINALLY answered all my questions about taper-crimping straight-walled "rimless" pistol cartridges like the .45acp:

I bought a case guage that meets SAAMI specifications for the caliber I'm reloading (1 for 9mm & 1 for.45acp). I took a factory load and put it in the case guage, it dropped right in, flush with the rim of the guage. I took it out and tried to put it in the wrong end of the guage, it went about half-way, hmmm, there appears to be a taper there.... Next I dropped that round into the barrel of my pistol, which I had field stripped for this purpose. The factory round head spaced properly per this drawing I got from another forum:

Next I tried reloading some cartridges. When I got to the seat/crimp stage, I adjusted the die per the instructions that came with it. The part that says adjust for proper crimp, I just adjusted til the round dropped into the case guage all the way and then dropped out when the guage was turned over.I also double checked by verifying that it properly head spaced in my pistol's barrel, no fiddling with micrometer to "measure" the crimp. In my opinion, measuring a taper crimp is like trying to measure the wingspan of a gnat, each measurement is likely to produce a slightly different results.

If you set your taper crimp just enough so that it will properly headspace on YOUR pistol -AND NO MORE, you just can't go wrong as far as crimping. I'll leave the argument about bullet setback and neck tension to those more knowledgeable than I.

By the way, your reloading manual say's not to ROLL crimp "rimless" cartridges. Its the "rimless" cartridges that headspace on the mouth of the cartridge. Rimmed cartridges that are designed to be used in traditional revolvers often use bullets with a cannerule designed specifically for a roll crimp.

I don't taper crimp any more since I purchased a Lee factory crimp. Like said earlier the bell needs squashing down. I have found correct constistent diamater and uniformity more important.

[RickB]

The case neck tension can be increased by reducing the size of the expander, assuming the sizer is doing its job. The rule of thumb that I've seen/heard is that the expander (the cylindrical part that is followed by the sharper funneled area that bells the case) should be no more than .002" larger than bullet diameter. If, for instance, you are using .451" bullets, your brass is a little tired, and the expander is .453", you might not be getting as much tension as you want. Reducing the expander to .452" could fix it. When I started loading .44-40, it seemed to me that the sizer was a compromise, so the loader could use bullets between .427"-.429", but it was too loose for .427", so I sent it back and had them turn it down a bit, and then it worked perfectly.