Undersizing 40 S&W Brass

[Steffes]

Background

I have been looking to switch to limited division for nearly a year now and finally found the pistol I was looking for. I picked up a Tanfoglio Witness Elite Limited in 40S&W in October and I've been working on reliable function since then. Admittedly I have caused myself undue problems by my choice in bullets and powders limiting me to loading longer than 1.200" as I had stockpiled several thousand 200 grain bullets prior to finding the gun. Prior to switching to limited, I had shot single stack and loaded 45 ACP using fast pistol powders like Bullseye, VV N310 and WST, so those were the powders I had on hand starting the 40S&W project.



The first problem I encountered was with the new style magazines for the Witness pistols. The K40 and K10 both have their issues as related to competition use. The K40, 40S&W mag has a spacer in the rear of the mag that limits OAL to 1.145" (a no-go for my component selection) and the K10, 10mm mag has a control rib down both sides of the magazine which I found limits the usable capacity to about 18 rounds when running the Henning 141 mag extensions and Grams guts. Research indicated that the "old style" 10MM magazines were what I would need for my application (40 long, 20 round mag) so I found a guy in Colorado with a stash of both old style mag bodies and Henning mag extensions. I picked up several and got to work.

The second problem I encountered was with the old style magazines. The new manufacture gun (manufactured July 2014) was set up to use the new style K40 / K10 magazines. The old style magazines have smaller radius corners on the front edges which cause issues with the mag catch and mag well area of the gun. I spent about two nights sanding, filing and polishing the mag well to accept the old style magazines without binding / sticking in the gun. Once I got the gun cleaned up and the mag catch tuned for the old style magazine tubes, I found out the new Henning mag extensions are machined for the new style mag profile and will not fit on the old style tubes. I broke out the dremel and modified the mag extensions to fit the old style tubes. Now I had 141mm magazines with grams springs and followers that "should" hold 21 rounds of 40long.

The third problem I encountered was with feed reliability with the old style mag tubes. The reason there is an old and new style mag tube is that the old style mag tube is very nose-dive prone due to poor control rib and taper design. Henning recommends NEW brass for any reloading endeavor for these guns with the old style magazines to avoid nose-dive problems due to bulged brass. I am hopeful that I have found a solution to this issue - hence the purpose of this post. I'm also hopeful that this information will help others solve feed reliability problems with doublestack 40 guns. I'm also thinking the process I've developed will increase the capacity of a doublestack magazine by one round (or make your previously 19 reloadable / 20 round mag a 20 reloadable mag).

Brass Prep Process

I've tried 3 different methods for preparing 40S&W brass for reloading on a progressive press. The first method was simply to tumble the brass and start reloading with a standard Redding resizing die in station 1. This was TERRIBLE and for all practical purposes is not feasible. The Redding die causes massive "bands" at the bottom of even slightly bulged 40 brass and simply cannot size brass effectively. This results in rounds that are larger in diameter at the rear of the case than at the case mouth, which exacerbates the nose-dive tendency of a double stack mag.

The second method I tried was using a Lee Bulge Buster and a Lee Factory Crimp die to push-though size all the brass prior to putting them through the progressive. This slightly reduced the number of mangled cases, but only about 20% of the cases were useable after this process. I ended up using this method for about a thousand rounds during debug by push through sizing, then resizing with the Redding die in single operations. I would then inspect every case and cull out the ones with bulges remaining at the base. This was extremely tedious and still did not result in perfect function as the bases of the cases were coming out of the Lee die at about 0.422" or approximately equal to the case mouth of a finished round. This was much better in functionality, but not ideal for the amount of work required to conduct the processing and inspection.

The method I have settled on requires 3 resizing steps, and 3 resizing dies to accomplish, but results in range pick-up brass that is nearly 100% usable for my picky mag setup. Step 1 is shoving the fired cases through the Lee Factory Crimp Die using the bulge buster and a single stage press. Here is a picture of the setup I am currently using (highly engineered catch bucked atop the press).



Here is a picture of a fired case base measurement - they come in anywhere around 0.425" to 0.432" depending on the load and whose gun they came out of.



Here is a picture of a case being shoved through a sizing die using the Lee Bulge Buster attachment to a single stage RCBS Rock Chucker press.



Here is a picture of a case that has passed through the Lee Factory Crimp die - they come out around 0.421" to 0.423".



Once the rounds have all been sized down to around 0.422", I use a standard Dillon carbide sizing die for 40S&W as another "push-though" operation. The Dillon die is roughly 0.417" ID and the decapping assembly, when removed, allows enough room for the round to pass completely through the die body. This step is a bit of a squeeze and requires a liberal application of case lube to keep it going smoothly.

Here is a picture of a case that has passed through both the Lee and the Dillon dies - they come out around 0.416" to 0.417" at the base.



The final sizing step is to use a Lee Undersize Resizing Die in the progressive press to decap and resize prior to expanding for bullet seating. The Lee U-Die measures 0.411" at the tightest spot in the carbide ring. The ring is tapered and the portion nearest the shellplate is roughly 0.418" so there is no chance of causing the huge belt on the bottom of the cases like I was experiencing before.

This sizing process creates a cartridge that is smaller at the base than at the case mouth, resulting in more favorable nose-up pressure on the top rounds in the mag as well as more room for the rounds to stack on the way down. It has made my magazines 21 reloadable (they were 20 reloadable, but would "fit" 21 very tightly) and totally reliable. They are extremely close to holding 22 rounds (I'm guessing with more tuning I could squeeze the 22nd round in there).

Summary

I batch process my 40 brass off the progressive in two operations - 1st through a Lee Factory Crimp die and then through a Dillon carbide sizing die (important as this is the only brand available with the correct size carbide ring and pass-through capability). I finish it off with a Lee U-Die in the progressive press and the load I'm using is 4.2 grains of VV N310 with a 200 grain round nose flat point X-Treme plated bullet loaded to 1.200" OAL and taper crimped to 0.421". I found that a load length of 1.225" still leads to an occasional nose dive (1/100 rounds).

[SilverBolt]

If I had to do all that to shoot .40 in limited I wouldn't. I tumble/clean my .40 brass, use a Redding Dual ring size die, and crank them out on my 650. Typically I get 2-3 rounds out of 1000 that don't case gage. No issues at all feeding my 2011.

[ron169]

I agree. I run everything through a Lee u die. Probably get less than 1 percent that don't chamber check.

[Steffes]

To clarify, the process was adopted not due to chambering failures, but to improve round stacking in the old style Tanfo mag tubes. I never did have a problem failing a chamber check with any of the processes I tried.

[mach1soldier]

I could see this having some benefits on some of the stages I shoot. Mostly the added capacity or loadability.

Thanks for sharing.

It sure seems like a lot of work though. Holy cow.

[Steve RA]

Might consider a Case Pro.

[Steffes]

I chickened out in the match this weekend and only loaded 20 in the mags. Had an unloaded start stage where mags had to be on a table and the first part of the plan came to an 18 round array. Had a couple make ups and ran the gun dry. Didn't register to rack another round after the reload and wasted a couple seconds on a tap rack. If I had loaded 21, it would have went bang after the reload. Gun has an EGW barrel pin and no slide stop to lock the slide back empty.

[Steffes]

Might consider a Case Pro.

Casepro = $800+

Lee die - $20

Dillon die - $30

Elbow grease - $0

I will stick with the $50 investment and achieve the brass size needed for reliable function in my blaster

Besides, casepro is only going to size down to 0.423 or so (saami spec).

[Jaxshooter]

Tumble brass, Lee U die for resizing, Redding Micrometer Seating Die, Lee Factory Crimp Die. This is on range pick up brass loaded on a Dillon 1050 less than 1% failure rate with 180 gr BBI or MG 180 gr JHP.

[Steffes]

Tumble brass, Lee U die for resizing, Redding Micrometer Seating Die, Lee Factory Crimp Die. This is on range pick up brass loaded on a Dillon 1050 less than 1% failure rate with 180 gr BBI or MG 180 gr JHP.

You accept 1 / 100 rounds failing in a match?

[CHA-LEE]

Use an EGW U-Die as the push though and it will bring the brass down to .415 diameter. If you use case lube you will be able to push through just about any range brass on one go without doing multiple stages. The bear comes when you try to resize nickel plated brass. It is a lot harder material and takes a lot more effort to jam it through the U-Die.

To use the EGW U-Die for the push through you will have to drill out the decapping pin threads

[Steffes]

I broke the Redding die trying to do just that. The ring split in two after about 50 rounds. Thats why I pass through the Lee FCD first to bring down the effort to get it through a smaller die. I like your plan though - maybe I will skip the Lee and just use the Dillon (no mods required) which produces 0.416" dia brass. Thoughts? Don't really want to break another die, although the Dillon seems to have double the carbide in the sizing ring.

[Steffes]

My measurements indicate the Dillon die I have measures 0.4155 ID and the Lee U-Die measures more like 0.413.

[CHA-LEE]

I have undersized many tens of thousands of rounds using the same EGW U-Die. I did crack the carbide ring on one but that was the result of trying to force an upside down nickel case through it.

If you use case lube and avoid the nickel brass you should be good to go.

[earthshine402]

I've reloaded about 7k rounds of .40 using the EGW U die and Hornady One Shot - half for a G35, the other half for a 2011.. no issues..

I can't believe all that extra work you are attempting to do...

[captain037]

I use to egw - u die too and found that bullet inconsistency is the biggest problem. Try sizing a batch and case gauging them before belling. I'll bet they all drop. Mic your bullets and sort the oversized ones. Go from there. The only thing left would be brass thickness. A thick piece of brass and oversized bullet = problems.

[Steffes]

To clarify, the process was adopted not due to chambering failures, but to improve round stacking in the old style Tanfo mag tubes. I never did have a problem failing a chamber check with any of the processes I tried.

I use to egw - u die too and found that bullet inconsistency is the biggest problem. Try sizing a batch and case gauging them before belling. I'll bet they all drop. Mic your bullets and sort the oversized ones. Go from there. The only thing left would be brass thickness. A thick piece of brass and oversized bullet = problems.

[427Cobra]

I bulge bust all 40 brass that I shoot through my G35, then load as normal

[Kaskillo]

Case-Pro 100 will fix your problem and save you a LOT of work. I roll size all my brass before loading. I have tried U-dies, push thru dies and bulge busters (redding and lee) Case-Pro is hard to beat.

[Steffes]

What is the base diameter after casepro? If > 0.416 I am not interested.

[Cowboy1629]

You have a lot more patients and time than me. If it was that much work to make my Edge run consistently I would be looking for a different gun. I used to run my .40's through a U-die even though they would function just fine in the mag and gun without having to do that but they wouldn't always pass the case gauge. I needed a CasePro for my 9 Major and went ahead and got the 40 die with it as well. Now I don't use the U-die and everything passes the case gauge.

I hope you find an easier alternative than what you are doing now, good luck!

[dauntedfuture]

Wow, that's too much work for .40. I have used Hornady .40 dies and now use a lee U-die. I simply have never had an issue sizing .40 cases on a LNL, 550 or 650 with either one of those dies. I use range pick up .40 brass. Most of this is USPSA range pick up brass and newer glock 22/23 don't "glock" brass as much as the G1 and G2 guns do.

I check each loaded round of ammo in a case gauge for competition. I might find 1/200 that does not go for some reason and they still work fine as practice ammo.

I have had issues with ammo that's loaded a little long that would not chamber in a .40 M&P but would fit in the magazine. Long loaded .40 will not gauge as the bullet is too long. I have had some limited feeding issues in a .40 2011 for ammo that was loaded too short. these are all bullet seating related issues.

[Kaskillo]

What is the base diameter after casepro? If > 0.416 I am not interested.

I random picked 5x 40 S&W fired cases and after roll sized on Case-pro 100. I am getting 0.421" average. This is just rolled sized, NOT full length sized yet.

SAAMI is 0.424" - 0.010"

Edited January 16, 2015 by Kaskillo

[Kaskillo]

Might consider a Case Pro.

Casepro = $800+

Lee die - $20

Dillon die - $30

Elbow grease - $0

I will stick with the $50 investment and achieve the brass size needed for reliable function in my blaster

Besides, casepro is only going to size down to 0.423 or so (saami spec).

If your $50 setup gets the job done and you are satisfied, then look no further.

[OPENB]

Wow, that's a lot of work. I'd shoot a different gun before doing all that. But if you're happy that's all that counts.