.40 S&W pressure

[epj]

I have just started loading .40's, though I have been reloading 9's and .45's for decades. I keep seeing references that lead me to believe the .40 is a ticking thermo-nuclear device waiting to kaboom.

All this didn't sound just right to me, so I did a little research. According to my Lyman 48th Edition, the high end .40's run about 23,000 CUP. That's certainly more than the .45 or .38 Special, but the lowly 9mm high end loads run almost ten thousand units higher. Lyman recommends Bullseye as a go-to powder for both if my memory serves. While there is certainly the potential for an overload with fast burning powder, the same potential certainly exists in the rest of the cartridges listed. Does the .40 have a bad rep due to folks trying to make a 10mm out of it for competition purposes?

 

[johngalt]

I don't load .40, but max SAAMI pressure is much higher than you stated: 36000 psi. Of course you don't have to load it to max.

A few years back I was interested in getting a .40, tried out a buddy's Glock 23 (or 22, I forget which). I didn't like it - recoil was worse than a .45 auto, had a very sharp crack to it.

Looking at the reloading data, I was also unimpressed. The .45 auto, using the same weight bullets, are capable of as high or higher velocity than the .40. The .45 is capable of launching heavier bullets than the .40 can. It can do it all at 15000 psi less pressure, and this isn't even considering .45 +P (which I'm not interested in).

I personally like low pressure cartridges better than high pressure. I like cartridges that can get it done at lower pressures.

 

[Vulcan Bob]

I would not reload for the .40 S&W unless the firearm Im useing it in had a fully supported chamber. It seems that there has been many instances where the case will blow out where the case was not supported by the chamber. This is usually at the six o-clock position where the feed ramp is.

 

[cp1969]

I am quickly becoming a fan of JohnGalt, and not just because of his catchy screen name. ("Who is John Galt?")

Once again, I second his well-reasoned counsel. The lower the pressure that gets the job done, the better.

 

[epj]

I don't load .40, but max SAAMI pressure is much higher than you stated: 36000 psi. Of course you don't have to load it to max.

A few years back I was interested in getting a .40, tried out a buddy's Glock 23 (or 22, I forget which). I didn't like it - recoil was worse than a .45 auto, had a very sharp crack to it.

Looking at the reloading data, I was also unimpressed. The .45 auto, using the same weight bullets, are capable of as high or higher velocity than the .40. The .45 is capable of launching heavier bullets than the .40 can. It can do it all at 15000 psi less pressure, and this isn't even considering .45 +P (which I'm not interested in).

I personally like low pressure cartridges better than high pressure. I like cartridges that can get it done at lower pressures.

The Lyman manual doesn't give the SAMMI max, just the max recommended load. As stated, the 23K maximum loads are given in CUP, not psi. Looking at the Hodgdon data, there are some loads for the .40 that are 30K+CUP. They give a lot of data, some in CUP, some in psi. The Lyman data is all CUP, and there is a definate difference in the 9 and 40 per their data. Perhaps they are either wrong, or only load wimpy loads.

 

[handgunner356]

Most of my reloading data has starting loads for the .40S&W running 25,000psi with upper loads 32-33,000psi. I would not load ANY .40S&W loads with a powder as fast as Bullseye. Unique and Universal Clays are a couple of good powders for the 40, but stay with medium or slower powders for it. A good crimp is very important also, bullet setback can really increase pressures and cause you to have a bad day.

 

[Dragon88]

I *think* the 40 S&W has a bit of a bad rap pressure wise for a few reasons. First, the partial supported chambers of guns like the Glock. It's interesting to me that problems aren't mentioned with higher pressure cartridges such as the 9mm, but nonetheless, the "glock kaboom" is out there. Second, people trying to load the .40 up to the same level as it's daddy, the 10mm. The .40 was created to provide a low- to mid-range 10mm load in a smaller case in a smaller pistol. Trying to cheat and get 10mm performance out of it is risky business.

If you stick to published 40 S&W data and load it within SAAMI specs, you should have no problems at all. It is subject to all the same mistakes as other loads; overcharges, doubles charges of fast powder, etc. Load it correctly and load smart and it's just as safe as the other cartridges out there IMO.

 

[jepp2]

Some examples of chamber support are shown in the picture below.

The 40 does headspace off the mouth of the case. The taper crimp only needs to close the flare for bullet seating. The key to avoiding setback is sufficient neck tension, not crimp.

 

[WILDPIG]

The .40 pressure curve is a sharp spike, thus, the sharp, abrupt, snappy recoil. The .45 ACP is more of a bell-shaped pressure curve. That is why the recoil feels different.

I have used CLAYS to great success for mild, clean, and very accurate .40 loads. Just use the data printed on the can (bottle). I had best luck with Winchester primers.

WILDPIG

 

[Skip Sackett]

The SAAMI spec is the exact same for standard 9MM and the 40S&W for maximum pressure, 35,000psi. I had the publication that corresponded to handgun cartridges but am unable to find it at this time.

Lyman, unlike Speer uses test barrels for the most part, to test their rounds and since there is no direct correlation from PSI to CUP, one needs to watch out when trying to interpolate data.

I load for the 40S&W, and I do it a lot. I just don't do it ignorantly. What determines how I load it is the firearm that I am shooting it out of. If it's a revolver designed for 10MM that's one thing. If it is my Glock 22, that is a whole 'nuther animal.

Slower powders for the unsupported chamber firearms will give you a win/win. More velocity, lower pressure.

Here is my load, it is from the Hodgdon Data site. 6.6gr SR4756 with a 180gr XTP gives 1018fps @ 28,800psi. Now, let's take their uber fast power, Titegroup and compare. Same bullet, 4.7gr gives 978fps only the pressure to get that done goes to 33,300psi. Guess why I chose the SR4756 load! Just seems to be smart to me. I could have used the minimum charge of Longshot and gotten better results than that but I have a bunch of SR4756. (Don't tell anyone but I have even gone above the 6.6gr to see what would happen! Not much, but I felt I had the 8,000psi (approx) window to play with.)

History has proven that some firearms have problems. I had a KB with Clays, another uber fast powder, in the 40S&W in a Browning High Power. I used Lyman data with a 175gr LTC bullet. It was .5gr over Hodgdon's maximum for that weight of bullet. KBs are no fun and if it were me, I would take all precaution to make sure they didn't happen. What makes us a little different than animals is that we have the ability to reason. Seems we should use it from time to time, like with this issue.

FWIW

 

[cp1969]

I also have "Who is John Galt" bumper stickers

Cool. I use that screen name on another site and it simply ENRAGES some liberals. I could post "kittens are sweet" and would still be viciously attacked.