Help with 40 S&W

[glaizinman]

Hey guy's I need some advise. I have been loading for awhile now I load 45 acp, 9mm,357 mag, 556/223 I even loaded the 40 S&W. But it was a while ago anyway with everyone saying how dangerous it can be with pressure and so on I'm a little freaked lol. Anyway to the point the Lyman 49th says trim to ..845 and the Speer #14 says .840 a lot of my case measure .835 will that be ok? I know with like the 45acp no big deal. While I'm asking I will ask for powder suggestion. I'm using RMR180 gr plated fn hey guys thank you in advance you guys always have been a wealth of knowledge.
Dave

 

[Lennyjoe]

I guess I’m an oddball because the only pistol brass I’ve ever trimmed was 44 mag.

As for powder, lately I’ve been using 7.0 gr of Longshot under plated 180’s for range loads. Have put about 3K down range in several different .40’s without issue

 

[glaizinman]

I guess I’m an oddball because the only pistol brass I’ve ever trimmed was 44 mag.

As for powder, lately I’ve been using 7.0 gr of Longshot under plated 180’s for range loads. Have put about 3K down range in several different .40’s without issue

Lennyjoe I have never trimmed pistol brass either. My concern is it being so much shorter than trim length. Maybe causing too much pressure. I hear Long shot really works good for 40 S&W

 

[crestoncowboy]

Ive trimmed 460 and 500 as well as 44 magnum. In the tens of thousands of 40 and 10mm I haven't had to trim anything

I do nothing different in the .40 than I do in the 30 or so other calibers i load for.

 

[Walkalong]

Trim length has absolutely nothing to do with pressure and any length you mentioned is safe to use.

I never trim .40 brass and have no idea how long they all are.

What powder charge you use and how deeply you seat the bullets is all you need to be concerned with as far as pressure and safety goes.

My concern is it being so much shorter than trim length. Maybe causing too much pressure.

Nope, rest easy.

 

[fxvr5]

Case length does not affect pressure. Cartridge overall length does because it determines how deep the bullet is in the case.

 

[glaizinman]

Case length does not affect pressure. Cartridge overall length does because it determines how deep the bullet is in the case.

Fxvr5 thank you I will start loading some 40's have a great eve

 

[Walkalong]

Precision 180 gr TrFP @ 1.128 +/- .002 OAL (No longer made, but SNS makes the same bullet. I loaded them at 1.130 +/- .002)


SNS 140 Gr TrFP @ 1.130 +/- .002 (Good for mouse fart loads, but I prefer 180 Gr for full/near full power)

 

[glaizinman]

Precision 180 gr TrFP @ 1.128 +/- .002 OAL (No longer made, but SNS makes the same bullet. I loaded them at 1.130 +/- .002)
View attachment 827070

SNS 140 Gr TrFP @ 1.130 +/- .002 (Good for mouse fart loads, but I prefer 180 Gr for full/near full power)
View attachment 827076

Walkalong I feel much better now you took out all my worries. I just heard so many horror stories about the 40 having a lot of pressure. I really enjoy this site I have learned so much you guys are awesome .Walkalong thank you

 

[1KPerDay]

I would argue that all things being equal a shorter case will have higher pressures than a longer case IF the bullets are seated to an equal DEPTH IN RELATION TO THE crimp groove, as in revolvers. This almost never happens however unless you adjust seating depth for the shorter cases. However in this case, your OAL is determined by the seating plug and ostensibly all of your loaded rounds will have the same OAL regardless of whether one case is 10 thousandths shorter than the other. In other words, it won't matter, as these gentlemen have stated.

And I don't trim semi auto pistol cases either. ;-)

 

[fxvr5]

Walkalong I feel much better now you took out all my worries. I just heard so many horror stories about the 40 having a lot of pressure. I really enjoy this site I have learned so much you guys are awesome .Walkalong thank you

There's a lot of paranoia and misunderstanding about the 40. In fact, it's no different than any other cartridge with respect to pressure. The guns and chambers and brass in which the 40 is used should be designed to handle it's pressure, just like every other cartridge. Here's some of the history on where the 40 get its bad reputation - it's all in the past now (presumably/hopefully): https://en.wikipedia.org/wiki/.40_S&W#Case_failure_reports

The 40's pressure is not unusually high with a max limit of 35,000 psi. The 9mm has the same pressure limit. Other semiautomatic pistol cartridges have higher limits, such as the 10mm (37,500 psi), 38 Super (36,500 psi), 357 Sig (40,000 psi), 9X23 Winchester (55,000 psi). But even the lowly 45 ACP (pressure limit 21,000 psi) can fail if the brass is bad or there is insufficient chamber support. That's why you can't be reckless when loading the 45 either. But if you're wise and stick with published data with any cartridge, you'll be fine.

 

[LiveLife]

40 S&W ... everyone saying how dangerous it can be with pressure and so on I'm a little freaked ... Lyman 49th

Since you are referencing Lyman #49, you will notice Lyman #49 40S&W start/max charges to be higher than other published load data. Keep in mind this is due to Lyman using larger .401" test barrel instead of more typical .400" - https://www.thehighroad.org/index.p...ads-exceed-new-book-max.840763/#post-10913220

So slug your barrel and if groove-to-groove diameter is .401", use Lyman load data; but if it is .400", use more conservative load data like from powder manufacturers. Be safe.

Page 362 of Lyman #49 showing .401" groove diameter of test barrel

And if you are using mixed range brass with unknown reload history and condition of brass, consider these:

• Published load data are often tested using NEW brass that are more malleable and can contain pressures better than mixed range brass that have been fired/reloaded multiple times and work hardened to not contain pressure as well. I reserve known once-fired brass (brass I saw go from factory boxes to pistols) for max loads but when using mixed range brass, I tend to stop at high-to-near max load data for my powder work up, especially for higher pressure calibers and when using Max/Working OAL/COL shorter than published.

• Mixed range brass that have been work hardened and less malleable may experience more brass spring back after seating bullet and taper crimping which decreases neck tension and increases bullet setback (Also check out this myth busting thread on bullet setback). Due to this, I now check bullet setback for load development, especially for near max loads . There have been quite a few KaBoom threads where case wall failure occurred even though below max charges were used and double charges were ruled out (As reduction in OAL can significantly increase chamber pressure). For peak chamber pressure, it's not the "Finished OAL" but "Chambered OAL" that matters.

And if you want to pursue greater accuracy from your 40S&W loads, consider loading them longer than SAAMI max of 1.135" - https://www.thehighroad.org/index.php?threads/rmr-180gr-fmj-rnfp.847523/#post-11050244

 

[lordpaxman]

Everyone gave you great advice as usual. I don't trim .40's and don't even measure them. I do pay attention to COL.

While I'm asking I will ask for powder suggestion.

That depends on what you're loading for, in my case I started shooting USPSA and so chose faster powders like Titegroup, WST and N320. The slower WSF, N340 and CFE Pistol also work well but I prefer WST out of all these especially with a plated bullet.

 

[LiveLife]

My concern is it being so much shorter than trim length.

I never trim .40 brass and have no idea how long they all are.

While straight wall semi-auto calibers headspace off case mouth, if resized case length gets too short, they will headspace off extractor.

Taken this to extreme, 40S&W chambered in 10mm is an extreme case of short "trimmed" 10mm case that will headspace off extractor and still fire.

So, don't worry about resized length of your straight walled semi-auto brass.

 

[glc24]

6.9 - 7 gr. of Longshot with Xtreme 180 gr plated FP at 1.125" OAL works well in my G23.