Effect on OAL change in .40

[Stormin.40]

I recently loaded and shot my first 180 grain .40 lead flat point reloads, no leading and very accurate. My favorite load was 6.4 grains of HS-6 with a OAL of 1.125. I loaded 5 each of 6.0, 6.2, 6.6, 6.8, no over pressure signs on any recovered brass.

Now to my questions, the bullets I have are designed for the 38-40 revolver so they have a crimp grove, my taper crimp with an OAL of 1.125 puts the case mouth at the very top of the crimp grove, but not over the grove, so it isn't really holding the bullet:banghead: I think if I shorten the OAL to 1.120 I can get the crimp over the grove and make it hold the bullet properly. Do I need to start all over at the minimum charge 6.0 grains or would it be safe to load up 50 rounds at 6.4 to verify which load I liked the best? How much is shrinking the OAL by 0.005 going to change the pressure and velocity?

I checked the last round out of each 5 round batch to check for bullet set back and there was none, but I would feel more comfortable with these loads if the bullet actually head spaced on the case mouth like the .40 is designed to do.

 

[Steve Koski]

.005 isn't gonna matter. Shorten them up.

 

[rsrocket1]

Your post is a little ambiguous.
Are you shooting this in a revolver using moon clips? If so, you don't care about headspacing on the case mouth and are perfectly fine roll crimping if setback is that important to you. If you are using the rounds in an autoloader, you don't need to crimp and if you are, be sure to check headspace in your disassembled barrel to make sure the bullets aren't sitting too deep in the chamber.

As Steve said, 5 mils isn't going to matter at your loads. You're considerably below max pressure and you'll be about 2.5% higher in pressure and about 5 fps faster (you won't be able to tell the difference)

 

[Stormin.40]

Sorry these are in an auto loader, good to know the .005 won't matter, I will go ahead and load some up.

be sure to check headspace in your disassembled barrel to make sure the bullets aren't sitting too deep in the chamber.

I am curious what you mean here, forgive me if this is a rookie question. Are you suggesting checking for rounds that are too long and therefore don't chamber completely? I thought that the deeper a bullet started in the chamber the better? I have loaded and shot other rounds as long as 1.130 in my Beretta without issue so 1.120 surely wouldn't be an issue.

 

[wr400]

My loading book says 1.135 An no shorter~

 

[Stormin.40]

I have seen 1.125 as the minimum OAL but never 1.135? I have Lyman and Speer loading books along with powder mfg. recommendations.

Maybe I should leave well enough alone, just thought that since the case mount wasn't holding the bullet I may be asking for trouble down the road, these are just plinking loads so I doubt there will be any set back. I wasn't able to push the bullet in any further against my bench which is why I thought I was safe originally.

 

[PO2Hammer]

Hodgdon data for the .40 is 1.125" and a max of 6.9 grains HS-6 with a jacketed hollow point (XTP). A lead flat point should be at least .005" shorter in length, probably quite a bit shorter, so going with 1.120" should be fine. You're below max for jacketed data, your bullet doesn't seat as deeply, and lead will produce less pressure than jacketed.

 

[wr400]

My Lyman is showing 1.135 for the overall cartrige leanth an 1.125 for oal for the bullets! I hope I am not missing somthing?

 

[PO2Hammer]

The 1.135" is probably max cartridge length for .40 in general, the 1.125" is probably for that particular load.

 

[popper]

180 TC/FP lead with no crimp groove in .40, load COL to mag length. Taper crimp, who cares about the groove, IF you properly crimp, just to get rid of the flare. I'm not familiar with the 38-40 bullet you are using, if it's not the correct dia. for your gun, the crimp (or OAL) won't matter.

 

[noylj]

I may be confused, but DO NOT ROLL CRIMP for an auto-pistol. It doesn't matter where the crimp groove is on the loaded case as it is NOT of any significance. IF it bothers you, don't order revolver bullets for your pistol.
I find that 1.160" is about the minimum useful COL in my .40s (I have never loaded as short as 1.140"), and generally I load to about 1.200". Do not ever load to less than the manual's COL and in almost ALL cases, load LONGER.
The .40 is particularly sensitive to bullet set-back, so a longer COL is a built in safety margin.

 

[LiveLife]

+1 on the taper crimp for 40S&W. Not familiar with the 38-40 bullet, but is the diameter compatible with your barrel's groove diameter? (should be .001" larger than the groove diameter of the barrel).

I would not worry about the crimp groove showing as long as the rounds fed/chambered reliably.

You should use the OAL that will reliably feed/chamber in your pistol when manually fed from the magazine without the bullet hitting the rifling.

 

[Stormin.40]

The 38-40 is .401, so it is the right diameter. The bullet manufacturer recommended crimping just over the crimp grove, yes taper crimp, so OAL of 1.120. I haven't loaded over 1.130 for my pistol yet and all the factory loads I have measured seem to be in the 1.120 - 1.125.

I thought the taper crimp headspaced on the case mouth so the crimp would be an important part of holding the bullet from setback. This being said my test rounds did not setback and I only removed the bell of the case and the case mouth was not crimped to the bullet, it was over the crimp grove @ 1.125.

 

[popper]

rimless cases headspace on the case mouth. The 38-40 is a bottleneck rifle bullet, sometimes used in revolvers (cowboy action). Load them as long as will cycle in your semi. Neck tension should prevent setback, TC to remove the bell. I just load and shoot. .40 set back issue appears to occur for LEO's that chamber the same round many times.