Alaskapopo Posted March 28, 2016 Share Posted March 28, 2016 (edited) 40 Long (10mm loaded length)[/url ] The reason for this experiment which was to buy a 40 Smith and Wesson conversion barrel for my Glock 40 (10mm long slide) and then have the barrel opened up to accept 40 bullets loaded to 10mm length (1.260) was twofold.1. To save money on brass. 10mm brass is about .14 cents a piece from Starline while 40 brass is about free for me from range clean up. 2. To in theory gain more reliability. The shorter case should be easier to eject. The barrel I used was a Lone Wolf conversion barrel. The control load in 10mm that I was trying to match using 40 sw brass is as follows 8.2 grains of Long Shot behind a Montana Gold 200 grain FMJ bullet. Overall length was 1.257 in the 10mm and with the 40 it ended up at 1.255.In theory if you load the 40 to the same overall length you will have the same sized combustion chamber and essentially the same pressures. This will not work if you work with lighter bullets as you will not be able to seat them out of the case as long to match 10mm length.I started with a max load in 40sw data from the online Hodgdon reloading manual.Starting load was6.5 grains average velocity over 5 shots was 945 spread was 27 standard deviation was 107.0 grains average velocity over 5 shots was 1004 spread was 110 standard deviation was 417.5 grains average velocity over 5 shots was 1098 spread was 46 standard deviation was 207.8 grains average velocity over 5 shots was 1136 spread was 33 standard deviation was 138.0 grains average velocity over 5 shots was 1175 spread was 23 standard deviation was 108.2 grains average velocity over 5 shots was 1174 spread was 26 standard deviation was 10I checked the brass for signs of pressure after each shot fired. I saw no signs. Here is a picture of a piece of .40 brass fired with 8.2 grains of Longshot next to a 10mm case with the same load.I loaded 15 shots for each batch. Once the chrono testing was over I shot some targets and plinked. No malfunctions. This barrel ended up being about 42 fps slower than the 10mm stock Glock barrel. I attributed that to polygonal rifling vs conventional rifling and the differences in individual barrels. Accuracy seemed on par with the Stock Glock barrel 2-3 inches’ groups at 25 yards. I hope this was helpful. I wanted to find a way to not have to worry about losing my 10mm brass and I am happy with the results. Edited March 28, 2016 by Alaskapopo Link to comment Share on other sites More sharing options...
PKT1106 Posted March 28, 2016 Share Posted March 28, 2016 Interesting. Two questions. Why the need to open the chamber up for 40 bullets? 40 & 10 use the same bullets, right? Second, is there enough bullet in the case for the case to get a good grip and hold the bullet in place (ie: minimal set back)? Link to comment Share on other sites More sharing options...
ericm Posted March 28, 2016 Share Posted March 28, 2016 APP: Thanks for the info as well as responding to my thread about loading to 10mm level in my .40 STI Edge. Looks like you have plenty of bullet in the .40 case judging by the 10mm "wasp waist" ring on the case in the picture. I assume the Lone Wolf barrel is fully supported and it looks like long shot is a good powder to try. If you do any work with 180 gr bullets, please post that. What is the equivalent spring on the 10mm factory Glock? 18#, 20#, etc.??? How do you Alaska boys use the 10mm? Close-in animal stuff, heavy winter clothing stuff, etc.??? Thanks, I just knew this could be done... ericm Link to comment Share on other sites More sharing options...
Alaskapopo Posted March 28, 2016 Author Share Posted March 28, 2016 Interesting. Two questions. Why the need to open the chamber up for 40 bullets? 40 & 10 use the same bullets, right? Second, is there enough bullet in the case for the case to get a good grip and hold the bullet in place (ie: minimal set back)? You need to open up the lead in the chamber if not the bullet would be smashed into the rifling raising pressures. No set back issues. The 10mm is unusual in that so much of the bullet is seated in the case compared to rounds like the 9mm and .45 acp. These rounds passed the push test I do and I also checked oal after chambering them with no set back. Pat Link to comment Share on other sites More sharing options...
Alaskapopo Posted March 28, 2016 Author Share Posted March 28, 2016 (edited) APP: Thanks for the info as well as responding to my thread about loading to 10mm level in my .40 STI Edge. Looks like you have plenty of bullet in the .40 case judging by the 10mm "wasp waist" ring on the case in the picture. I assume the Lone Wolf barrel is fully supported and it looks like long shot is a good powder to try. If you do any work with 180 gr bullets, please post that. What is the equivalent spring on the 10mm factory Glock? 18#, 20#, etc.??? How do you Alaska boys use the 10mm? Close-in animal stuff, heavy winter clothing stuff, etc.??? Thanks, I just knew this could be done... ericm Not sure on the springs will have to check. I use the 10mm as a woods gun and a 9mm as a city gun. I may work with the 180 but the OAL will have to be shorter and I will have to reduce the loads. I may try a 180 with the same powder charges as the 200. But I an reluctant to have that little of the bullet in the case if I kept the same overall length. Edited March 28, 2016 by Alaskapopo Link to comment Share on other sites More sharing options...
N1vram Posted June 6, 2016 Share Posted June 6, 2016 Thanks for sharing your results. I've been curious about this. If you are loading to 10mm oal. Couldn't you have just used the 10mm Glock barrel? Sent from my iPhone using Tapatalk Link to comment Share on other sites More sharing options...
warpspeed Posted June 6, 2016 Share Posted June 6, 2016 Thanks for sharing your results. I've been curious about this. If you are loading to 10mm oal. Couldn't you have just used the 10mm Glock barrel? Sent from my iPhone using Tapatalk If you do that, you end up headspacing off the extractor which is not ideal to say the least. Link to comment Share on other sites More sharing options...
ghost21 Posted June 6, 2016 Share Posted June 6, 2016 Just one question, And I think I know the answer! Loading 40,to 10mm length ,wouldn't you get a lot of burn residue in part of the chamber, I.e. the short brass not touching all of the chamber ! Say just like shooting 38 special in a 357 mag chamber all the time ,The powder residue will over time build up in that part of the chamber between the mouth of the special case and the exit end of the cylinder! Link to comment Share on other sites More sharing options...
mayassa Posted June 7, 2016 Share Posted June 7, 2016 I learn something every day here. I have a glock 40 and shoot 10mm light (40 cal) all the time. No FTF/FTE yet with 500-600 rounds through it. Link to comment Share on other sites More sharing options...
Alaskapopo Posted June 8, 2016 Author Share Posted June 8, 2016 Just one question, And I think I know the answer! Loading 40,to 10mm length ,wouldn't you get a lot of burn residue in part of the chamber, I.e. the short brass not touching all of the chamber ! Say just like shooting 38 special in a 357 mag chamber all the time ,The powder residue will over time build up in that part of the chamber between the mouth of the special case and the exit end of the cylinder! No because this is being fired in a 40 SW chamber with a long lead to accommodate 10mm length loaded ammo. (essentially long loaded 40 just longer than normal) Link to comment Share on other sites More sharing options...
ghost21 Posted June 9, 2016 Share Posted June 9, 2016 Gotcha ! Link to comment Share on other sites More sharing options...
cevers57 Posted March 5, 2017 Share Posted March 5, 2017 Very interesting modification for the G-40. I have a question, with the 40 conversion barrel how well does it eject the brass, how far is it thrown? My mild problem with a 40 S&W barrel from KKM in the G-40, is the brass barley falls out with my G-35 minor loads and major loads. Right now i'm still burning through 8lbs of Bullseye I was glad to buy when there was nothing on the shelves. Currently using Blue Bullets 180 & 195 grains. Would a slower powder help create more slide rearward movement, or to move this heavy slide does one just have to load over a 200PF to make the slide eject the brass better/further? The G-40 overall- very fun in 10mm or .40. Link to comment Share on other sites More sharing options...
Kellybrown1962 Posted February 2, 2020 Share Posted February 2, 2020 You can i reload 45 Gap brass as 45 acp since so much of it is found at the range but 10mm brass is about the same price. But I would imagine a steady diet of them could possibly cause erosion and cause a sticky chamber. If your carrying when your hiking i wouldnt want to have anything but new 10mm ammo even if hand loaded Link to comment Share on other sites More sharing options...
peterdaws Posted February 3, 2020 Share Posted February 3, 2020 I run a Bul M5 in .40 for IPSC competition. The barrel is throated and I load ammo to 1 1/4". Back in 2011 I built a 6" 10mm top end for it to use on a trip to South Africa. I was having trouble getting it to feed so out of curiosity I tried some of my .40 loads in it and they fed. At which stage I had a light bulb moment and realised that long .40 could be loaded as if its a 10mm. So I just took the gun in .40 and some rounds loaded to 10mm power with 180grn. XTPs. Unfortunately the planned Blessbock hunt fell through but it made a reassuring car gun Link to comment Share on other sites More sharing options...
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