Shooting .40 S&W in a Glock 20 using the Mihec 200gn FN

[Whistler]

The GUN
* Glock 21 with IGB 10mm Auto barrel (I wrote Glock 20 in the topic because of the 10mm barrel). The stock barrel is of course .45 ACP (foot note: I've tried .45 GAP in it and it works well).
http://i1306.photobucket.com/albums/s569/whistler1984/2013-07-06184733_zps7dbde3cc.jpg

The WHY
* Hands may be too large for a standard size Glock frame.
* 10mm Auto brass is expensive, whereas the .40 S&W brass is cheap.
* If SHTF you can use either .40 or 10mm.
* Great conversation starter.
* The .40 is a very competetive cartridge in dynamic/practical shooting.

The HOW
* The Glock usually headspace the case on the extractor contrary the normal headspacing on the case mouth.
* The 10mm Auto OAL ensures proper feeding in 10mm magazines (.40 S&W factory cartridges have shown to work as well).
* The 200gn FN bullet is plenty long enough to give 10mm Auto OAL in .40 S&W brass without exposing too much of the lube groove.

The STUFF
* Mixed .40 S&W brass
* Hornady LNL progressive press (old one, serial number #000146)
* Hornady decapper/resizer
* Lyman M-die expander
* Hornady seater with the crimper lapped out (so the die body can touch the shellplate)
* Redding taper crimp
* Mihec 200gn FN (solid) weighing 206gn with 50% WW / 50% pure lead alloy
* Home cooked lube (50% beeswax, 40% molybden disulfide lithium grease, 10% alox)
* CCI small pistol primer
* 4.4gn Vihtavuori N320 to reach IPSC Major factor (actual factor 175)

The PICS
(the Mihec 200gn FN with moly/beeswax to the left and Carnauba Red on the right)
http://i1306.photobucket.com/albums/s569/whistler1984/20130906_182655_zpsfe8bbfa1.jpg

(.40 in 32.00mm OAL on the left with a true 10mm Auto cartridge to the right)
http://i1306.photobucket.com/albums/s569/whistler1984/20130906_200016_zps2dbc2957.jpg

(Accuracy at 25 meters (27 yards) wasn't great, but will do for small IPSC matches)
http://i1306.photobucket.com/albums/s569/whistler1984/574645e4-e176-4f7d-9caa-fcbc7085dee4_zps1f6ea91f.jpg

The PROOF
(local IPSC competition of 100 rounds)
http://youtu.be/gibQRL_rBK4

The BUTS
* Carbon/lube/lead deposit in the forward area in the chamber where the case is too short compared to a 10mm Auto case, similar to shooting a .38 Special in a .357 Magnum chamber.

[nicholst55]

That is a great solution the the problem of 10mm brass availability! I would think that as long as you thoroughly clean the chamber after each outing, you should not experience any problems.

[300savage]

What is the meplat measurement on that bullet if I may ask.

[Whistler]

http://i94.photobucket.com/albums/l109/jdecar1/guns/OreoMiha10-40s.jpg

[scb]

"* The Glock usually headspace the case on the extractor contrary the normal headspacing on the case mouth."

I've never heard of this. Can you show me where this assertion comes from?

[Whistler]

It comes from the simple fact that the for the chamber too short .40 S&W case sit in the chamber without releasing from the extractor letting the firing pin reach the primer. If it headspaced on the case mouth only it would release from the extractor and get stuck in the chamber, as is the case when trying the same thing in for example a 1911.

[Oreo]

Head space is not really the correct term for this. All glocks head space on the case mouth like any other semiauto straight walled pistol. In this particular useage the case is held by the extractor with enough tension that the firing pin is able to ignite the primer. A quirk of design between the 10mm & 40sw makes it possible.

A better way is to use a 40sw barrel with a long enough throat that the 1.260" oal 40sw rounds chamber ok. This way the case properly head spaces on the mouth. It safely allows upper-medium strength 10mm loads using 40sw brass. The 1.260" oal requires the use of 10mm mags though so doing this means having a large frame glock, 10mm mags and a conversion barrel.

[Whistler]

...or you can do it this way and enjoy all the advantages it brings. Without having to buy extra parts, which may not be allowed or easy/cheap to aquire in some countries. Buying an extra barrel for a pistol costs about $550 in Sweden, not including the fee for applying for an extra license (need one for every extra licensed part) and not including the 4-8 weeks of wait for license approval. That's IF you can get a dealer to get one for you, which is not very easy in the first place.

About headspace, I'd expect the best way to explain is that we go from case four from the top to case two, though not a rimmed case but in the extractor groove on the rebated rim.

http://upload.wikimedia.org/wikipedia/commons/0/03/Case_headspace_en.jpg

[halfslow]

I have been doing this for years now.

There are only two potential problems I can think of:
1- The fouling buildup in the front of the chamber, which can easily be dealt with by cleaning as you have been doing.
And
2- a tiny potential for extractor failure due to the firing pin pushing the case forward (although I think the shock to the extractor when the case smacks the ejector is huge by comparison).
I solved this one by buying an additional extractor which I marked by polishing off the finish and used only when firing the .40 S&W ammo.

[sargenv]

You are sort of better off just getting a replacement barrel in the correct size.. sure it works in a pinch, but why do it when the actual correct barrel is already available for it? I don't really see any reason to do it except for "Hey everybody, watch this!". Just sayin'..

[Oreo]

Well, Whistler has a valid point that in some countries other then the USA the cost / benefit of a second barrel just isn't there. In the USA however it makes good sense to buy the proper barrel for this kind of cartridge.

[xacex]

Several people do this on a regular basis, and shoot 40 out of their Glock 20's, or 29's to save on cost. It has been documented several times in postings, and video's all over the net that shooting 40 out of the 10mm Glocks is quite accurate, and in most cases more accurate in comparison to say a Glock 22 in 40 S&W. I would attribute this to the weight of the slide on the large frame guns vs small frame. Granted, many dissagree with the practice, but it is no different than a 357 magnum using 38 special. In auto loaders care must be taken to clean the chamber before the 10mm is used again, but the OP already addressed that issue. There have been thousands of rounds of 40 shot out of 10mm Glock barrels without issue. Personally, I have seen a couple of Glock 20's that have fires thousands of rounds of 40 because of the cost and availability of 10mm, and report no issues. Flame suit on.:takinWiz:

[nicholst55]

Several people do this on a regular basis, and shoot 40 out of their Glock 20's, or 29's to save on cost. It has been documented several times in postings, and video's all over the net that shooting 40 out of the 10mm Glocks is quite accurate, and in most cases more accurate in comparison to say a Glock 22 in 40 S&W. I would attribute this to the weight of the slide on the large frame guns vs small frame. Granted, many dissagree with the practice, but it is no different than a 357 magnum using 38 special. In auto loaders care must be taken to clean the chamber before the 10mm is used again, but the OP already addressed that issue. There have been thousands of rounds of 40 shot out of 10mm Glock barrels without issue. Personally, I have seen a couple of Glock 20's that have fires thousands of rounds of 40 because of the cost and availability of 10mm, and report no issues. Flame suit on.:takinWiz:

It's difficult to argue with success. Just sayin'. ;)

[Whistler]

I appreciate the feedback, guys. I've tried hard to find other reports of people shooting .40 in 10mm, but only found theories until I tried it myself. As always I reinvent the wheel, but at least I'm still having fun doing it. In Sweden the Glock 20 is an enthusiast firearm, and many who get it are frowned upon because of arguments like "Why waste your points on something you can barely use in competition?". After the third to fifth gun the police department usually say no and demand extensive competition results to show that you need the gun and that it is competitive. In such a legislative world the advantage of using a reasonably cheap and competetive cartridge as the .40 S&W the usefulness of the Glock 20 really goes up.

[dk17hmr]

I bought a Lone Wolf 10-40 barrel for my G20 and shoot it a lot more than I do with the 10mm barrel. Mainly because I load a lot of 40 S&W ammo. The next step will be to get the barrel throated so I can load 40's long and load to 10mm power.

[Oreo]

From what I've read the chambers in LW barrels need to be opened up for the larger diameter of cast boolits but the throats might be just fine for this application as they are. My own LW 10-40 barrel will chamber a 1.250" 40sw round just fine.

[dk17hmr]

Well I know what I'm trying tonight..... see how long I can go with my LW 40 barrel. It shoots my normal 40 plinking load very well so I haven't played with load work in it.