40S&W HELP Please!!

I am ready to beat my head against the wall. LOL! I have a earlier post about loading 180gr lead bullets over WST. I have decided to start at 3.6gr which should be really light. My problem now is getting these loads to pass the plunk test. I have run my OAL in to 1.101" and still get a little sticky. Please Help.

If everything else is okay: You have no choice but to shorten up until it does pass.

Well my only fear has been my load data. I can't find any written data for this bullet and WST. From some old data that someone posted I decided to start at 3.6gr. With these bullets seated at 1.101" there is very little room left in the case. I have my taper crimp at .421", so I should be good there.

Ummm, I don't mean to sound rude, but I don't think you should be doing what you're doing.

If you're not sure why your reloads aren't passing spec, you really shouldn't be voyaging into uncharted load data, much less in a .40 which is notorious for being unforgiving.

Stop, evaluate your equipment and use published load data.

Ummm, I don't mean to sound rude, but I don't think you should be doing what you're doing.

If you're not sure why your reloads aren't passing spec, you really shouldn't be voyaging into uncharted load data, much less in a .40 which is notorious for being unforgiving.

Stop, evaluate your equipment and use published load data.



This is the reason I am asking. I realize I'm way shorter than my plated loads. My plated loads that I use for IDPA is 3.9gr of WST at a OAL of 1.128". It's a very soft shooting load. As a matter of fact it's the starting charge per Hodgdon's website, but with a longer OAL. I have searched for load data using 180gr lead with WST, but have only found data for Tightgroup, and W231. I for sure don't care to use Tightgroup. To be safe I dropped the starting load for 180gr FMJ and WST down by 10%. I know I will be safe there to start with, and good chance I will be to lite at my normal OAL. It just concerned me having to drop my OAL to 1.101".

What diameter are the bullets? And are they measuring out to what they advertised?

Sounds like there is something different in the bullet profile. Can you contact the bullet maker and ask their advice. Is your barrel, chamber, lead, etc. all cleaned out? If there is no obstruction, I think the bullet maker would be my next stop. Surely they have encountered this problem before.

First post here. Hi all.

I had the same problem with my 40 S&W loads, couldn't pass the clunk test. It drove me crazy. It turned out to be my crimp.

FWIW, I wouldn't shorten the OAL. I would keep it to 1.125". The problem must be either the cartridge is too wide somewhere or the chamber is obstructed (assuming the chamber is in spec).

I would start by calibrating my caliper since you've been taking measurements. Make sure it's set to zero when closed. Then measure the case mouth to make sure it's at .421 - .422". Then measure the rest of the case to make sure it's .423 - .424". It could be there is insufficient crimp or the case is not completely resized. I resize the entire case by lowering the resizing die a half turn beyond touching the shell holder. Some call it over resizing but I think it helps feeding.

Also, scrub the chamber clean with a 9mm brass brush by going back and forth with cleaning solvent.

"Well my only fear has been my load data. I can't find any written data for this bullet and WST. From some old data that someone posted I decided to start at 3.6gr."

HUH?
Do you suppose there is a reason for that?

"Well my only fear has been my load data. I can't find any written data for this bullet and WST. From some old data that someone posted I decided to start at 3.6gr."


Seriously? why not just fill the case up and see what happens? Darwin would be proud of actions like these

Take a marker and color the bullet and case to see where it is catching. I followed some of you previous thread with WST, but I cannot remember what gun you are loading for if you posted it. My suggestion would be to start over with a load that you can find some data on so you are not playing in such an uncharted area. I have tinkered with loads inwhich there was no plublished data, but I did have a reference point and only changed one thing such as FMJ data with lead at same col, lead data for lead at different col, or FMJ data for FMJ at different COl. Once again I dont have any expierence with WST but if you are sure that 3.6 is a light load try it. You may even load a few a little lighter to see what happens and if it cycles the slide. Once while working up a load with my 30-30 I had almost no data to start with, but I was really wanting a load to work. I got to the point to where I was pushing the max load and the only thing I had in common in my manual was the powder listed. On test firing I put the rifle in a rest and pulled the trigger with a rope. After I was satisified that the gun was not going to blow up, I shouldered it while firing. I got the velocity I was wanting, but the accuracy really sucked. Im sharing this with you to stress two points. One is at some point you may reach the point to where you are GO or Blow and you have to decide if you should pull the trigger. Second point is that once you get there you may not like how the load preforms. Just remember as you work up the load and shorten the col, the less case volume you have and the higher the pressure will be. You may get to the point which you are over max pressure before you get enough powder in the case to cycle the slide. I would hate for you to post I Blew Up My Gun especially if you have a Glock. I have never used WST so I cannot comment on it. What I do know is HP-38 (231) and bullseye when loading cast bullets for 40s&w. I run my lee 175tc casted from wheelweights seated at 1.098 on top of 3.8gn of bullseys to run in my G23 with lone wolf barrel. I cannot remember the velocity off hand but it is a mild shooting load. I dont like titegroup for cast loads but I would use it if it were all I had. What other powders do you have?

I have checked my crimp. It's at .421. I'm not applying anymore crimp than what I have. To be honest I wouldn't mind using .422" crimp. I have plenty of case tension. My cases measure .417 mid case, and .419 just above the head. I use Dillon dies which size them down pretty good. This is not my worry. My bullets are hitting the lands. They are too long with this bullet profile. I'm using 180gr TC FN. My bullet diameter is .401. I check about 50 different bullets. They range from .401-.4015. So the manufacture did a pretty good job. I have never had problems with Missiouri Cast in the past with .45acp. Jeff Holt I am well aware that there could be a reason data is not there for WST. I am willing to go with W231 or WSF, but I use WST for Compitition with 180gr plated. I did find some data earlier from a older Winchester load phamplate. I would be fine at a OAL of 1.125", but it worried me at 1.101". That's the reason I asked! Still with W231, or WSF 1.101" is pretty short for 40s&w. I am also new to reloading. I have only been at this for a year and only have about 30,000 rnds of 40s&w, 45acp, and 38spl under my belt. Tis the reason I asked the question. I have already broke down my loads to start over. I am wiling to use W231 or WSF, but the OAL still worries me.

gahunter12 , Thanks for asking our advice.

Ummm, I don't mean to sound rude, but I don't think you should be doing what you're doing.

If you're not sure why your reloads aren't passing spec, you really shouldn't be voyaging into uncharted load data, much less in a .40 which is notorious for being unforgiving.

Stop, evaluate your equipment and use published load data.

I had the same problem with my 40 S&W loads, couldn't pass the clunk test. It drove me crazy. It turned out to be my crimp.

Welcome readyeddy. Have a cigar for posting (what I think) is the most likely explanation.

I had my answer composed in my head before reading the rest of the thread, so will give only those items not already covered.

1) Good idea to make up a dummy round without primer or powder so you can check chamber fit before committing the flammables to the loading. You only "waste" one bullet and one case. If the dummy round does not pass feeding and chambering without a hitch, cure the problem before doing anything else.

2) Measure a factory round (or any round that chambers and feeds perfectly) and compare. Even calipers that don't have a correct zero will at least be able to tell you which dimensions are different.

3) Paint the nose of the bullet with magic marker or white-out or nail polish or something and chamber it. If rifling (or lead, copper or powder build-up) smudges the stuff on the nose of the bullet, clean your chamber. (oops, already mentioned)

4) The length of the full cartridge has to be short enough to feed through your magazine, feed ramp and chamber. That is the maximum OAL.

The length of the full cartridge is not important to the minimum OAL.

It is the length of the space UNDERNEATH the bullet that is important. Do not let that go below the minimum for that powder/bullet combination. Unfortunately we cannot measure that dimension directly, so we use the next best proxy, the OAL.

Measure the length of your bullets (several of them and take the average). If your stock of bullets do not vary in length, you are good. If they do, you will have to take that into account. Don't ask me how. My reply would be WAY too long. Start a new thread for that. Measure the length of the bullet that is named in your loading manual. If they are identical, you are good. If they are not, apply an adjustment to your OAL equal to the difference. (If your slugs are shorter than the manual's, your OAL can be safely shorter by the same amount. If your slugs are longer, then you should use an OAL correspondingly greater.)

In this way, you keep the SPACE FOR THE POWDER BURN comparable between your cartridges and the ones from the loading manual.

5) How's your (taper) crimp look? Nice, clean and sharp?

6) Does a freshly fired case pass the "clunk" test? Does a freshly sized case? Does a freshly belled (uncharged and without a bullet in it)?

Diagnostics. I love a puzzle.

I hope my thoughts are some help.

Lost Sheep

I was going to suggest the same thing, make up a dummy load, color it with a marker and if that doesn't show well enough, soot the round up over a candle. Any contacts will make a mark so you can see where it is sticking. I'm betting on the crimp area as well. When you load the bullet .010" longer, does the case sit .010" further out of the chamber? If not, then the OAL probably isn't the cause.

Take a marker and color the bullet and case to see where it is catching. I followed some of you previous thread with WST, but I cannot remember what gun you are loading for if you posted it. My suggestion would be to start over with a load that you can find some data on so you are not playing in such an uncharted area. I have tinkered with loads inwhich there was no plublished data, but I did have a reference point and only changed one thing such as FMJ data with lead at same col, lead data for lead at different col, or FMJ data for FMJ at different COl. Once again I dont have any expierence with WST but if you are sure that 3.6 is a light load try it.


I am going off of my 180gr FMJ data that I use for my Berry's bullets. Hodgdon's website says 3.9gr - 4.3gr of WST at a OAL of 1.125". I have settled on 3.9 for my Platted bullets for Compitition. 3.8gr was a little too lite for the plated bullets. I would have 2 or 3 fail to lock on empty mag out of 100 rnds. I based my 3.6 off of 10% reduction which is actually 3.52gr. I was advised by a friend that loads WST with lead that 3.5gr would not work, and 3.6 may be to lite, but start there and try it. Even if I could get my OAL around 1.120" I would fill ok. By the way I have done the marker trick. That was the first thing I did when they would not pass the plunk test. This is why I realized te bullet was hitting the lands. I based my dummy rounds off of my FMJ measurements. The only difference is my lead bullets are .587" long and my FMJ are .578" long. Which is another reason I threw up a RED FLAG.

I have checked my crimp. It's at .421. I'm not applying anymore crimp than what I have. To be honest I wouldn't mind using .422" crimp. I have plenty of case tension. My cases measure .417 mid case, and .419 just above the head. I use Dillon dies which size them down pretty good. This is not my worry. My bullets are hitting the lands. They are too long with this bullet profile. I'm using 180gr TC FN. My bullet diameter is .401. I check about 50 different bullets. They range from .401-.4015. So the manufacture did a pretty good job. I have never had problems with Missiouri Cast in the past with .45acp. Jeff Holt I am well aware that there could be a reason data is not there for WST. I am willing to go with W231 or WSF, but I use WST for Compitition with 180gr plated. I did find some data earlier from a older Winchester load phamplate. I would be fine at a OAL of 1.125", but it worried me at 1.101". That's the reason I asked! Still with W231, or WSF 1.101" is pretty short for 40s&w. I am also new to reloading. I have only been at this for a year and only have about 30,000 rnds of 40s&w, 45acp, and 38spl under my belt. Tis the reason I asked the question. I have already broke down my loads to start over. I am wiling to use W231 or WSF, but the OAL still worries me.
A shorter reiteration of what I consider the most important point of my earlier post (and the most salient to your post quoted here).

Calculate the space UNDER the bullets (your loads and the manuals') and act accordingly.

Lost Sheep (who suffers from long-windedness, and makes his readers suffer, too)

gahunter12 after reading you last post and checking the hodgon site to double check, there is only .4 grain difference between start load and max load with WST. In light of this my only advice would be to use a different powder. I rechecked you other thread and seen where you said that you had w231. With the small difference between min and max has me thinking that the pressure will spike as you reach the max load for the componets that you are using. This gives you less room to work and like I said you may be over pressure before it cycles your gun. Like I said though I have never used WST so I cannot say for sure.

gahunter12 after reading you last post and checking the hodgon site to double check, there is only .4 grain difference between start load and max load with WST. In light of this my only advice would be to use a different powder. I rechecked you other thread and seen where you said that you had w231. With the small difference between min and max has me thinking that the pressure will spike as you reach the max load for the componets that you are using. This gives you less room to work and like I said you may be over pressure before it cycles your gun. Like I said though I have never used WST so I cannot say for sure. Yep I agree! Thats the reason for this post. I have checked all my measurements and determined that The bullet was hitting the lands. With the lead bullet being longer than my FMJ bullets, and plated bullets, I felt uneasy with the possible results of less availible volume left in the case for such a fast powder. One thing that caught me off guard was the availible data for Tightgroup being its faster than WST. I would say WST may spike quicker than Tightgroup. I would have thought it would be the other way around.

I would be fine at a OAL of 1.125", but it worried me at 1.101". That's the reason I asked! Still with W231, or WSF 1.101" is pretty short for 40s&w. I am also new to reloading.

1.100" is too short. The link at the bottom lists many IPSC loads but none are as short as 1.100". Play it safe and stick with published load data even if you have to choose different components.
www.precisionbullets.com/PDF/maashl40sw.pdf

Big, fat, chunky lead bullets and short, tight chambers are a tricky mix. It's because of the bulkiness of the ogive.

One might argue that the short OAL sometimes required to chamber such rounds is dangerous, but it is amount of gas released by the ignited powder and the space remaining in the case that matter.

Loading physics says that as the space is shrunk, so must be the amount of gas released at ignition. That means less powder.

Big, fat, chunky lead bullets and short, tight chambers are a tricky mix. It's because of the bulkiness of the ogive.

One might argue that the short OAL sometimes required to chamber such rounds is dangerous, but it is amount of gas released by the ignited powder and the space remaining in the case that matter.

Loading physics says that as the space is shrunk, so must be the amount of gas released at ignition. That means less powder.

I agree. The ogive is a little chunkier than my plated or FMJ bullets. These bullets are also longer by .011" than my FMJ and .20" longer than my plated bullets all the same weight. I did find data for W231 with the exact same style of bullet but 175gr set to 1.100" OAL in Lyman manual. I may drop the start data down by 15% below start charge and try that. Reason for 15% is the data is for 175gr, where I'm using 180gr, plus my 180's are more than likely longer.

FYI, I use two 40S&W TCFP bullets from Missouri Bullet sized .401" with .421"-.422" taper crimp and OALs listed below. They feed/chamber reliably in most pistols I have shot them out of. Perhaps your barrel's start of rifling is much quicker (shorter leade)?

Here's the previously posted 1999 Winchester load data (http://www.thehighroad.org/attachment.php?attachmentid=159609&stc=1&d=1329800605) for WST and if you are concerned, start low and work up until you have reliable slide cycling. Referencing load data for heavier 200 gr bullet (max 3.5 gr) and 170 gr bullet (start 4.0 - max 5.2 gr), you could initially work up 3.6-4.0 gr. If you have reliable slide cycling and improving accuracy trends to 4.0, you could consider continuing the work up to around 4.4 gr. If accuracy tapers off, I would stop there.

Perhaps this thread may help - http://www.brianenos.com/forums/index.php?showtopic=82363

http://www.thehighroad.org/attachment.php?attachmentid=160779&stc=1&d=1331502659
http://www.thehighroad.org/attachment.php?attachmentid=160932&stc=1&d=1331700222
http://www.thehighroad.org/attachment.php?attachmentid=160933&stc=1&d=1331700222

BDS. My bullets are from Friendswoods Bullets. It looks just like the IDP5#. They will chamber at 1.120", but fail the plunk test because they are hitting the lands. I played a little longer last night and found I can go 1.105" without hitting the lands. I also taper crimp to .421". My plated and FMJ loads are loaded at 1.130". I know my camber will except up to 1.135" with a TCFP FMJ, but they touch slightly in my mags. Reason for dropping back to 1.130". The only difference I see in design between my FMJ and Lead TCFP's is the Ogive is shorter and the bearing area is longer. Hince they seat deeper into the case not leaving much room.

If you are concerned about increase in chamber pressure from bullet base seating deeper in the case, you could conduct your powder work up from the start charge you feel comfortable.

Once you reach the powder charge that provides reliable slide cycling and feeding/chambering/extraction/ejection, it would be up to you to determine how much higher to go.

Just to add to what others have posted already, I think there are some reasons why powder manufacturers stop publishing particular bullet/powder combinations over the years. Perhaps different powder provided better accuracy or pressure map that was flatter?

I sometimes go against the grain, but when I have hard time finding certain load data without much support from more experienced reloaders, I look for more tried and true/tested/popular loads supported by currently published load data.

I mean, there are many other powders/loads good for 180 gr lead TCFP bullets and WST is good for 45ACP. ;) Just my 2 cents.

Peace.

I mean, there are many other powders/loads good for 180 gr lead TCFP bullets and WST is good for 45ACP. Just my 2 cents.

You are correct! I love WST for 45acp! It also works great for 40s&w with plated or FMJ!

Are you using an aftermarket barrel? Possibly Lone Wolf?

Are you using an aftermarket barrel? Possibly Lone Wolf?


No. Factory XDm barrel. I'm going to load some test rounds tomorrow at 1.105" using W231 based on the load recipe in Lyman's manual. Lyman's lists the recipe using 175gr lead TCFP instead of 180gr at a OAL of 1.100". I am aware that Lyman's uses a .401" test barrel with .401" bullets. So considering there barrel size is .001" bigger than mine, and the use a 175gr bullet, I plan on dropping my charge 10% below there recomened start charge.

Anywhere from 4-5 gr. 231 for MBC #5 look-alike in XDm barrel is FINE. Load a dummy to hit the lands and then back off .02. Crimp just to remove the seating flare. Works for every 180 TC I've used including my own cast. You don't really gain anything with WST over 231.

gahunter12, I share your sentiment. After being happy with Missouri 125 gr 9mm RN loads with W231/HP-38 and Promo, when I did load development for 9mm SWC bullet, I noticed the bullet base got seated deeper in the case neck. 4.0 gr of Promo was just below the bottom of RN bullet and the same powder charge would have compressed under the SWC bullet.

Since W231/HP-38 is much denser, it was no problem for me to seat the bullet down to 1.045" OAL and still not compress the powder charge. I did use .3 gr below Hodgdon's start/max charges for 125 gr CN (3.9-4.4 gr) which was similar to 1999 Winchester load data for 124 gr RN (3.3-4.0 gr).

As to your 40S&W 180 gr lead "Friendswoods" TCFP, it may not be the bullet nose profile but the pistol as many others have posted that they need to load their bullets shorter for XD/XDM.

http://www.thehighroad.org/attachment.php?attachmentid=151344&stc=1&d=1319305687

Thanks bds! I understand. I know the .40s&w is a high pressure load, and don't care to KB my gun. I'm going to take it slow, and work up. I would really like to use these bullets as a good practice source and save my plated bullets for IDPA events. At my rate I shoot 200-300 rnds per week out of my ESP gun. Thanks for all the knowledge and help.

If you're using a verified starting charge, I wouldn't worry too much about 0.03" difference.

I've read about some Sierra tests that showed a specific 9mm load doubled in peak pressure when the bullet was setback 0.3". You're talking about a low charge and 0.03" of "setback." Pressure surely won't double, nor get anywhere close. 0.3" setback would put your OAL at 0.830". Think on that. :)

I load my 9mm MCB bullets to 1.05" to clear the lands. It's just the nature of that bullet.

What is the Plunk test? Plink Test? I load to book stats only (or at least try to real hard) but haven't heard of your tests with these names. Educate please. Thanks.:)

Bob, we are referring to the "barrel drop" test for semi-auto pistol rounds that headspace on the case mouth.

It is done to check the test/dummy round (no powder/no primer) is loaded to Max OAL without hitting the rifling and enough taper crimp is applied to allow the test round to fully chamber. With the barrel's chamber pointing up, the test round should fall into the chamber freely with a "plonk/plink" noise indicating the headspacing of case mouth on the forward edge of the chamber.

Once you determined the Max OAL using the barrel drop test, next you determine the Ideal OAL that will reliably feed/chamber from the magazine. Starting with the Max OAL, feed/chamber the test round from the magazine by manually releasing the slide without riding the slide with your hand and incrementally decrease the OAL until you can reliably feed/chamber the round from the magazine. Some pistols like XD/XDM require much shorter OAL than typical to reliably feed/chamber from the magazine.

Once you determined the Ideal OAL, proceed to powder work up using currently published load data. For me, if my Ideal OAL results in base of bullet being seated deeper than the published load data, I will decrease the start charge by .2-.3 gr. If I can't find current load data for the same bullet type/nose profile, I will reference older published load data.

What is the Plunk test?

"Plunk" test is where you drop a finished round in your chamber with the barrel removed from the gun. the finished round should give you a "plunk" shound as the case mouth head spaces off the camber ridge. When you flip the barrel over the round should freely fall out without having to shake the barrel. If your rounds are too long your bullets will hit the lands in the barrel. This is a good time to check for proper head space. Alot of times you can set your OAL within the specs of the recipe to suite your guns needs. For example my Plated and FMJ loads call for a 1.125" OAL. I set mine at 1.130" which is where my gun performs the best.

Ok with a little investigating, I have about .078" of air space between my powder and base of my bullet inside the case. This is using W231 data from Lyman's manual. I have dropped the starting charge by 10%, and don't plan to go over 4.0gr. If I can't get reliable function I will go even slower with my powder type.

That is 1 weird looking .40 TC bullet! Looks like a SWC with the nose cone going straight to the front drive band, which is quite small, and the nose is rounded off. Is any of the drive band above the case mouth? Mine seat about 11/32 into the case with 1/10 of the drive band out of the mouth. Any particular reason for getting those? Maybe you could trade for their 175 SWC. 4 gr. 231 should cycle your XDm easily. With only .078" you can't get 4 gr. Unique(slower powder) without a compressed load. Maybe bullseye(~3.5) would work better.

That is 1 weird looking .40 TC bullet!

That is a weird .40TC. The .40 TC's that I'm using are more like a regular FMJ TCFP with the exception of the bearing surface that seats in the case is alot longer and the ogive is shorter. Here's a pic of what I'm loading. http://www.friendswoodbullet.com/40S_W__10mm_180grain_FP/p132676_306825.aspx

I had the same problem using 180 Gr truncated cone cast in my XD 40
I was able to get them to work at 1.090. I loaded some up with 4.5 grains 231 @ 1.120, a load that I knew to work.
Using a different gun, that will feed about anything ( Hi-point carbine) , I chronoed that load- AVG 1036 FPS
Then, I tried 4.0 GR @ 1.105 - AVG 952 FPS
Then 4.0 @ 1.090 - AVG 950 , surprisingly no increase from 1.105

Using the velocity figures, I figured that my pressure should be safe.
Shot them from the XD, they averaged 850 FPS.
Have shot several hundred so far, only had 2 misfeeds, both blazer brass. Not sure why, but all-in-all a success

I had the same problem using 180 Gr truncated cone cast in my XD 40
I was able to get them to work at 1.090. I loaded some up with 4.5 grains 231 @ 1.120, a load that I knew to work.
Using a different gun, that will feed about anything ( Hi-point carbine) , I chronoed that load- AVG 1036 FPS
Then, I tried 4.0 GR @ 1.105 - AVG 952 FPS
Then 4.0 @ 1.090 - AVG 950 , surprisingly no increase from 1.105

Using the velocity figures, I figured that my pressure should be safe.
Shot them from the XD, they averaged 850 FPS.
Have shot several hundred so far, only had 2 misfeeds, both blazer brass. Not sure why, but all-in-all a success

That's good to here! I got all mine loaded at 1.106" +-.001". I started at 3.6gr,3.8gr,4.0gr,4.2gr of W231. All pass the plunk test, so we will see how they run. Going this evening.

gahunter12 - yes, that's the one I looked at, seems like a longer nose than anything I've loaded, i.e. MBC, xtreme, rainer, others. Requires you to seat deeper and have less space for powder. Mine are all 1.109 or longer and still fit the mag. Your look more like the right one in #29 with a flatted tip, I just wondered if there was a specific reason you chose that profile. I usually run 4.5-4.8 231 which is not a compressed load.

Ok with a little investigating, I have about .078" of air space between my powder and base of my bullet inside the case. This is using W231 data from Lyman's manual. I have dropped the starting charge by 10%, and don't plan to go over 4.0gr. If I can't get reliable function I will go even slower with my powder type.
Is that from the web of the cartridge case to the base of the bullet or from the top of the powder to the base of the bullet? When I first read your post I thought you meant from the web to bullet and my comments below are based on that assumption.

That (.078") does not seem like it would provide a lot of volume for the powder charge to burn properly. But I don't know, as I don't shoot .40 S&W. But my .357 has a lot more room than that. I have never been compelled to measure my 45ACP or 9mm free space, but I opine they would probably have a lot more, too.

If you take apart a factory round of the same (or close to the same) bullet weight, how much free space to you have?

Lost Sheep

Quote:
Originally Posted by gahunter12
Ok with a little investigating, I have about .078" of air space between my powder and base of my bullet inside the case. This is using W231 data from Lyman's manual. I have dropped the starting charge by 10%, and don't plan to go over 4.0gr. If I can't get reliable function I will go even slower with my powder type.
Is that from the web of the cartridge case to the base of the bullet or from the top of the powder to the base of the bullet? When I first read your post I thought you meant from the web to bullet and my comments below are based on that assumption.

That (.078") does not seem like it would provide a lot of volume for the powder charge to burn properly. But I don't know, as I don't shoot .40 S&W. But my .357 has a lot more room than that. I have never been compelled to measure my 45ACP or 9mm free space, but I opine they would probably have a lot more, too.

If you take apart a factory round of the same (or close to the same) bullet weight, how much free space to you have?

Lost Sheep

The .078" measurement was from top of powder to base of bullet. I shot my loads tonight. 3.6gr of W231 was fairly light and good groups. 3.8gr of W231 was nearly like a factory load. I didn't even try 4.0gr or 4.2gr. I am going to go back and try 3.5gr for function. At 3.6gr I had no problems at all. I'm a little worried about the 4.0, and 4.2 being to hot! I'm looking for practice rounds for IDPA practice anyway.

http://www.thehighroad.org/showthread.php?t=641229

?????? No thanks! Had a G17, and a G26, and currently own a G20 that I can't stand. Only reason I don't sell the G20 is because I carry it while pig hunting.