bruce282 Posted September 14, 2007 Share Posted September 14, 2007 I have a Glock 34 and a 17. I am getting ready to start reloading and ordered 1k of PD 147gr bullets. Got an email that they won't be ready for 6 weeks. OK I went to Midway to get some Hornady HAP bullets. I had the order all done and noticed that the 125gr HAP's were .356 and the 147gr TMJ were .355. Do I care? I did search but couldn't find this answer. Bruce Link to comment Share on other sites More sharing options...
Jake Di Vita Posted September 14, 2007 Share Posted September 14, 2007 Once you shoot .356, you can't go back to .355. If you are going to shoot both, make sure you shoot at .355 first. 9mm is .355 38 is .356 Link to comment Share on other sites More sharing options...
lcs Posted September 14, 2007 Share Posted September 14, 2007 Once you shoot .356, you can't go back to .355. If you are going to shoot both, make sure you shoot at .355 first.9mm is .355 38 is .356 Jake, What is the reason for "Once you shoot .356, you can't go back to .355" Larry Link to comment Share on other sites More sharing options...
Jaxshooter Posted September 14, 2007 Share Posted September 14, 2007 (edited) Wil Scheuman recommends shooting .356 bullets in .355 barrels. You can go to his web site and read the info there. You can shoot .355 or.356 and vise versa. Actually 38 is .357 diameter not.356. Edited September 14, 2007 by Jaxshooter Link to comment Share on other sites More sharing options...
JThompson Posted September 14, 2007 Share Posted September 14, 2007 (edited) You think that opens it up enough to have accuracy problems or lose gas? Edited September 14, 2007 by JThompson Link to comment Share on other sites More sharing options...
Jake Di Vita Posted September 14, 2007 Share Posted September 14, 2007 That's what I've been told by several gunsmiths Link to comment Share on other sites More sharing options...
G-ManBart Posted September 14, 2007 Share Posted September 14, 2007 Once you shoot .356, you can't go back to .355. If you are going to shoot both, make sure you shoot at .355 first.9mm is .355 38 is .356 It's generally true that .38 Super is .356 and 9mm is .355, but you can also get .38 Super and SuperComp barrels in .355. I have a KKM .38SC barrel in my Bedell and it's .355 (that's all it says, not even .38SC or anything else. They recommend shooting .355 for the first 4-7K and then trying .356 to see if they shoot better. If not, then continue shooting .355. I think it would take a lot of .356 bullets to make a .355 barrel wear to the point it won't shoot .355 bullets well. It's the depth of the grooves where the measurment is taken, so even a .355 bullet in a .355 barrel is getting squeezed through the bore a fair amount. Link to comment Share on other sites More sharing options...
JThompson Posted September 14, 2007 Share Posted September 14, 2007 Once you shoot .356, you can't go back to .355. If you are going to shoot both, make sure you shoot at .355 first.9mm is .355 38 is .356 It's generally true that .38 Super is .356 and 9mm is .355, but you can also get .38 Super and SuperComp barrels in .355. I have a KKM .38SC barrel in my Bedell and it's .355 (that's all it says, not even .38SC or anything else. They recommend shooting .355 for the first 4-7K and then trying .356 to see if they shoot better. If not, then continue shooting .355. I think it would take a lot of .356 bullets to make a .355 barrel wear to the point it won't shoot .355 bullets well. It's the depth of the grooves where the measurment is taken, so even a .355 bullet in a .355 barrel is getting squeezed through the bore a fair amount. That's about what I would think from an old machinist point of view. It's a valid point though and I'm glad it was brought up here as I never even considered it before. I'd like to see some data on it side by side wth pfs to back it up. Anyone got a couple of new barrels and some time? Link to comment Share on other sites More sharing options...
dirty whiteboy Posted September 14, 2007 Share Posted September 14, 2007 Seems like most of the MG bullets I ever mic'd were always a little under sized. But I'm sure most people buy them for their accuracy! Link to comment Share on other sites More sharing options...
1911onr Posted September 17, 2007 Share Posted September 17, 2007 One half of one thousand of one inch on each side of the barrel will not make much difference. Link to comment Share on other sites More sharing options...
davecutts Posted September 17, 2007 Share Posted September 17, 2007 After 25,000 zero .356 (121"s) I've been forced to switch to MG 121's at 355's. My Bedel with a KKM barrel still puts them all in a quarter at 25 yards. Link to comment Share on other sites More sharing options...
Allgoodhits Posted September 19, 2007 Share Posted September 19, 2007 I have a Glock 34 and a 17. I am getting ready to start reloading and ordered 1k of PD 147gr bullets. Got an email that they won't be ready for 6 weeks. OK I went to Midway to get some Hornady HAP bullets. I had the order all done and noticed that the 125gr HAP's were .356 and the 147gr TMJ were .355. Do I care? I did search but couldn't find this answer. Bruce It only matters if your gun's barrel prefers one over the other. I'll have to check a SAAMI manual, but I think the official bore groove diameter for 9x19 and .38 Super are both .355 and land diameter is .346. My recall is that .38spl is also .355 and .346 respectively, although most .38 spl bullets are .357 in jackets and .358 in lead. Keep in mind everything has tolerances expressed as a dimension +/-. So a barrel with a bore groove on the loose side of tolerance mated with bullets on the tight side of a tolerance may be a loose fit. FWIW the last box of 3,000 Hornady HAP bullets were labelled by Hornady as .355 although all of the marketing suggests the size as .356. Martin Link to comment Share on other sites More sharing options...
L9X25 Posted September 19, 2007 Share Posted September 19, 2007 I have had this conversation with Wil Schuemann. His opinion is that the additional gasses that blow by a .355 projectile do far more damage than the friction of the jacket sliding down the bore. He prefers to shoot .356 & .357 projectiles to eliminate as much of the "blow by" as he can. Link to comment Share on other sites More sharing options...
Allgoodhits Posted September 20, 2007 Share Posted September 20, 2007 I have a Glock 34 and a 17. I am getting ready to start reloading and ordered 1k of PD 147gr bullets. Got an email that they won't be ready for 6 weeks. OK I went to Midway to get some Hornady HAP bullets. I had the order all done and noticed that the 125gr HAP's were .356 and the 147gr TMJ were .355. Do I care? I did search but couldn't find this answer. Bruce It only matters if your gun's barrel prefers one over the other. I'll have to check a SAAMI manual, but I think the official bore groove diameter for 9x19 and .38 Super are both .355 and land diameter is .346. My recall is that .38spl is also .355 and .346 respectively, although most .38 spl bullets are .357 in jackets and .358 in lead. Keep in mind everything has tolerances expressed as a dimension +/-. So a barrel with a bore groove on the loose side of tolerance mated with bullets on the tight side of a tolerance may be a loose fit. FWIW the last box of 3,000 Hornady HAP bullets were labelled by Hornady as .355 although all of the marketing suggests the size as .356. Martin To be sure I checked the ANSI SAAMI manual and 9mm, .38 Super, .38 spl, ,357 Mag have as a STANDARD the barrel dimension as .355 diameter at groove and .346 from land to land. Of course gunsmiths rebarreling have taken liberty where they can in trying to find the perfect combo. The variations by gunsmiths are more than likely twist rate, not bore dimension difference, as not many barrel manufactures truly make barrels in different bore dimensions. They may market their barrel as a different dimension, but in reality they may mostly be .355 as an example. Recall the auto industry in marketing engine displacement whereby something called a 396, 427, 428 or whatever may have actually be several cubes different, but it sounded better or implied bigger and better! MJ Link to comment Share on other sites More sharing options...
Carlos Posted September 20, 2007 Share Posted September 20, 2007 (edited) I have had this conversation with Wil Schuemann. His opinion is that the additional gasses that blow by a .355 projectile do far more damage than the friction of the jacket sliding down the bore. He prefers to shoot .356 & .357 projectiles to eliminate as much of the "blow by" as he can. Another Schuemann fan here. Mimimizing "blow by" makes sense since barrels "wear out" by throat erosion and that process is accelerated by excessive blow by. Edited September 20, 2007 by Carlos Link to comment Share on other sites More sharing options...
shred Posted September 25, 2007 Share Posted September 25, 2007 I've got 100K on one Open Super and 50K on the other, the vast majority major loads using HAP bullets (which variously claim to be .355 or .356 or .3555, depending on the box) plus various other bullets in both .356 and .355. Neither barrel is worn out yet. Don't worry about it. Link to comment Share on other sites More sharing options...
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