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9mm major gas vs 40 S&W major gas


tag129

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Given the loads you specify, the 40 will make a little more gas, but at a lower pressure.  They both work the comp and you can get both to shoot dead flat if you want to.  As far as I can tell, the only real differences are with 40 you stay well within reloading guidelines (pressure), whereas with 9 Major, you are pushing the envelope.  The other difference is mag capacity.  You give up 3 rounds in 40sw 140 and 170 mags.

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tag, it may be possible to do that using only a comp.  I tried doing that with my first Open pistol.  It was 40sw and originally a 3-chamber, 3-port design that I later modified.  It ended up being 3-chamber, 7-port with the extra 4 ports being side bleeders.   One particular load using a 155gr and HS-6 made 172PF and was stupid soft.  If you didn't hear the loud bang when it went off, you would swear you were shooting a 22LR.  To get that combo to shoot FLAT, I had to go up to 188PF.  That was incredibly loud and hard on the hands and the gun.

My second Open pistol is also 40sw.  I has two 3/16" poppels and a 4-chamber, 5-port comp.  It shoots flatter with the same loads the old pistol used.  With some additional tinkering and a comp change I'll be able to get it to shoot flatter, or softer, but probably not both.

Recoil with either Open load is less than with my old Limited load of 180gr @ 172PF, so I have plenty of room to go for flatter rather than softer.  I'm fine with some dot lift, as long as it settles back down in the same place.  A fast split, at least for me, is 1 second, so there is plenty of time for the dot to settle before the second shot.

BTW, I don't feel handicapped in any way using 40 for Open.  It is a straight walled case and using the Lee carbide bullet crimping and resizing combo eliminates concerns about Glocked brass.  No so with the tapered 9mm case.  Many are now finding a lot more Glocked brass than previously and are buying roll sizers to fix the problem.  That being said, my next Open pistol will be 9mm for no other good reason than I want one.

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Its a reason why pretty much nobody uses .40 open guns, I played around with it myself just to see how it would be, and.. just not optimal, you can make it "almost ok" at best. 

+ special light bullets are much more expensive etc. 

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21 hours ago, tag129 said:

Hi everyone 

I was wondering how much more gas does 40 S&W major, 135 grn bullet has over 9mm major, 124 grn bullet. If both using the same powder    

Ex. 10%, 15%, 20% etc.   

 

I have one data point for you in terms of flatness. I have shot a lot of .40 open using 135 plated bullets. (I preferred 125 frangibles but that is another story). I finally got a 9mm and am using 124 and 121 plated plated bullets. My sole crossover data point is for Autocomp powder. I use 6.9 gr behind the 121's for about 172-ish PF. To get the 135s to major, I am using 8.3 gr and just barely making it. They feel similar. The guns are different. See the pics. The blue grip is the 9mm. The 40 has a metal frame and has quite a few rounds down the pipe. The 9 barrel is fairly new. In the typical vague terms, 40 is a bit less snappy. The .40 is louder. Both are fun :D 

 

rightside_small.jpg

LeftSideSmall.jpg

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On 2016-10-23 at 7:49 AM, zzt said:

tag, it may be possible to do that using only a comp.  I tried doing that with my first Open pistol.  It was 40sw and originally a 3-chamber, 3-port design that I later modified.  It ended up being 3-chamber, 7-port with the extra 4 ports being side bleeders.   One particular load using a 155gr and HS-6 made 172PF and was stupid soft.  If you didn't hear the loud bang when it went off, you would swear you were shooting a 22LR.  To get that combo to shoot FLAT, I had to go up to 188PF.  That was incredibly loud and hard on the hands and the gun.

My second Open pistol is also 40sw.  I has two 3/16" poppels and a 4-chamber, 5-port comp.  It shoots flatter with the same loads the old pistol used.  With some additional tinkering and a comp change I'll be able to get it to shoot flatter, or softer, but probably not both.

Recoil with either Open load is less than with my old Limited load of 180gr @ 172PF, so I have plenty of room to go for flatter rather than softer.  I'm fine with some dot lift, as long as it settles back down in the same place.  A fast split, at least for me, is 1 second, so there is plenty of time for the dot to settle before the second shot.

BTW, I don't feel handicapped in any way using 40 for Open.  It is a straight walled case and using the Lee carbide bullet crimping and resizing combo eliminates concerns about Glocked brass.  No so with the tapered 9mm case.  Many are now finding a lot more Glocked brass than previously and are buying roll sizers to fix the problem.  That being said, my next Open pistol will be 9mm for no other good reason than I want one.

ZZT 

Thx for the info, im trying to make my own comp.  3 port on the top, 2 on each side and 2 popper holes on barrel.  

Ultimately, I want the flattest and softest if  possible.    

I'm using longshot with 135 gr berry bullet.   

If you don't mind you can PM me  

thx 

 

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The biggest problem you will encounter, with 40 caliber and a compensator, is too much gas. I worked on 40 open loads for an entire summer and still never really got it right. 

Fire a round at a cardboard target, with the end of the comp 2 inches away from said target. You should have a clean bullet hole, and perhaps a bit of powder residue around the hole. Good luck reducing the amount of gas to where the target does not tear. I got to a point where the 2 ~ 3 tears were 1/2" long and could never get it any better. But then, with my initial loads I was getting 3 tears in the target 2 ~ 2 1/2" long. 

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I too spent a lot of time working up loads for 40 Major Open.  My current load is 155 Rainier bullet over 7.1gr Autocomp.  It shoots flat.  Most observers tell me the muzzle doesn't rise at all.  It does, but not by much.  This is the newer gun with two poppels and the comp.  It mostly recoils straight back and is harder on the hands than my older gun.  The reason is not enough gas to work the comp.  No, or almost no gas exits the front of the comp.  Moving to 8.2gr and the 135 Rainier makes more gas, but is deafeningly loud.  Same if I go to HS-6.  I need a grain more to make the same PF with the same bullet weights, so I get more gas, but even more noise with it.

I'm going to continue to experiment over the Winter.  I bought a new comp.  It is the EGW Ti comp designed for Bianchi cup or minor.  It has 5-chambers and 7-ports.  I'm hoping the extra baffle will  soften the hit to the hand.

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1 hour ago, Reshoot said:

The biggest problem you will encounter, with 40 caliber and a compensator, is too much gas. I worked on 40 open loads for an entire summer and still never really got it right. 

Fire a round at a cardboard target, with the end of the comp 2 inches away from said target. You should have a clean bullet hole, and perhaps a bit of powder residue around the hole. Good luck reducing the amount of gas to where the target does not tear. I got to a point where the 2 ~ 3 tears were 1/2" long and could never get it any better. But then, with my initial loads I was getting 3 tears in the target 2 ~ 2 1/2" long. 

What kinda comp are you using? 

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1 hour ago, zzt said:

I too spent a lot of time working up loads for 40 Major Open.  My current load is 155 Rainier bullet over 7.1gr Autocomp.  It shoots flat.  Most observers tell me the muzzle doesn't rise at all.  It does, but not by much.  This is the newer gun with two poppels and the comp.  It mostly recoils straight back and is harder on the hands than my older gun.  The reason is not enough gas to work the comp.  No, or almost no gas exits the front of the comp.  Moving to 8.2gr and the 135 Rainier makes more gas, but is deafeningly loud.  Same if I go to HS-6.  I need a grain more to make the same PF with the same bullet weights, so I get more gas, but even more noise with it.

I'm going to continue to experiment over the Winter.  I bought a new comp.  It is the EGW Ti comp designed for Bianchi cup or minor.  It has 5-chambers and 7-ports.  I'm hoping the extra baffle will  soften the hit to the hand.

I always get mixed up. Ports located on the top and chambers located on the sides. Am I correct? 

Is baffle same as chamber? 

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tag, a chamber is formed when you cut into a comp to make a port.  A baffle is the forward face of the cut.  You may have more than one port cut into a chamber.  Take a look at the comp in the ChuckS post.  Starting from the rear of the comp you have one up port.  The front wall of that port is a baffle.  Next is another up port and the front wall of that second port is a baffle.  There are two more ports moving forward, and there is a baffle between each.  When we get to the next opening(s), what do we call them.  Yes, there are two ports, one on either side.  So you could correctly call this an 8-port comp, but that does not tell you the whole story.

If you think of every division in a comp moving forward as a chamber separated from the next by a baffle, you give more information.  Chuck's comp is more correctly described as a 6-chamber, because it has six interior divisions and therefore six baffles.  The first four chambers have one up port each.  The next two chambers have two side facing ports cut into each, one on each side.  So it is a 6-chamber, 8-port comp.  That tells you how the comp is configured even without a picture.

Assuming there is enough gas to work them, the more baffles you have, the softer the gun shoots.  The more ports you have, the more gas you can produce and vent out the top or sides so none exits the front.  Gas that exits the front of the comp increases felt recoil.  Gas that hits the baffles reduces felt recoil.  Gas that exits up reduces muzzle rise.  Gas that exits sideways does not affect recoil, but that gas pushing on the baffle does.

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On 2016-10-31 at 0:11 PM, Reshoot said:

The biggest problem you will encounter, with 40 caliber and a compensator, is too much gas. I worked on 40 open loads for an entire summer and still never really got it right. 

Fire a round at a cardboard target, with the end of the comp 2 inches away from said target. You should have a clean bullet hole, and perhaps a bit of powder residue around the hole. Good luck reducing the amount of gas to where the target does not tear. I got to a point where the 2 ~ 3 tears were 1/2" long and could never get it any better. But then, with my initial loads I was getting 3 tears in the target 2 ~ 2 1/2" long. 

Thx reshoot 

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On 2016-10-31 at 3:33 PM, zzt said:

tag, a chamber is formed when you cut into a comp to make a port.  A baffle is the forward face of the cut.  You may have more than one port cut into a chamber.  Take a look at the comp in the ChuckS post.  Starting from the rear of the comp you have one up port.  The front wall of that port is a baffle.  Next is another up port and the front wall of that second port is a baffle.  There are two more ports moving forward, and there is a baffle between each.  When we get to the next opening(s), what do we call them.  Yes, there are two ports, one on either side.  So you could correctly call this an 8-port comp, but that does not tell you the whole story.

If you think of every division in a comp moving forward as a chamber separated from the next by a baffle, you give more information.  Chuck's comp is more correctly described as a 6-chamber, because it has six interior divisions and therefore six baffles.  The first four chambers have one up port each.  The next two chambers have two side facing ports cut into each, one on each side.  So it is a 6-chamber, 8-port comp.  That tells you how the comp is configured even without a picture.

Assuming there is enough gas to work them, the more baffles you have, the softer the gun shoots.  The more ports you have, the more gas you can produce and vent out the top or sides so none exits the front.  Gas that exits the front of the comp increases felt recoil.  Gas that hits the baffles reduces felt recoil.  Gas that exits up reduces muzzle rise.  Gas that exits sideways does not affect recoil, but that gas pushing on the baffle does.

Thx zzt 

i will try to develop a load first than I will start on the comp.  

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