kneelingatlas Posted June 10, 2014 Share Posted June 10, 2014 There seems to be a group of Open shooters very concerned with "compressed loads" and another which is not. Over the last two years I have done extensive load testing and have not had a single issue filling the case close to the rim with slow powder and pushing it down with the seated bullet. I started loading 9 Major with CCI SRP for fear of high pressures, but I saw so little flattening I stopped stocking two sets of primers and have gone to Federal SPP for everything.I pick up lots of brass at matches and see plenty with flatter primers than mine (even .40 cases...). So does anyone have a good reason not to compress powder (if you're loading 9 Major I don't think it's a question of "if" but "how much")?I have loaded as much as 10gr of SP2 in a 9x19 case with no ill effects or scary flat primers although it's pretty close to the rim Link to comment Share on other sites More sharing options...
Hi-Power Jack Posted June 10, 2014 Share Posted June 10, 2014 (edited) I think that increasing powder into a case is sort of linear in terms of pressure/velocity, usually. But, once you compress the powder, it's no longer linear - the pressure/velocity can spike - dangerously if not careful. Esp when you start getting close to compressed loads, you have to use a chrono and work up Very Slowly (more slowly than without a compressed load). Not forbidden - just a little more dangerous for the uninformed than a load that is not compressed. I used a compressed load of HS6 and 115 gr bullet for years, and had no problem, but I didn't like (personally) filling the case so high and having so little room for the bullet to hang onto the case. At least, that's My understanding - perhaps some ballistic experts will give us the correct answer, soon. Edited June 10, 2014 by Hi-Power Jack Link to comment Share on other sites More sharing options...
Sarge Posted June 10, 2014 Share Posted June 10, 2014 The only issue I ever had with compressed loads in my 9MAJOR loads was that with certain cases, over time, the oal would grow. Now, I don't recall if I had switched to the Udie yet but I'm pretty sure I had so if a compressed charge could push a bullet out of an undersized case that impressed me! The thing that concerned me most was loading so long that a very small amout of growth could cause problems in the mag or chambering. Link to comment Share on other sites More sharing options...
56hawk Posted June 12, 2014 Share Posted June 12, 2014 Only problem I've had with compressed loads was losing velocity when I added more powder. Haven't had that problem with my 38 Super open guns though, even when using N105. Link to comment Share on other sites More sharing options...
DRichardson Posted June 12, 2014 Share Posted June 12, 2014 (edited) It seems to be very different from powder to powder. In my testing 3n38, and 4756 don't seem to mind being compressed, I fact to make major in 38 super with 4756 it has to be compressed. With long shot in 9major I had a issue where even when adding powder the velocity didn't increase and the velocity started to drop when I added some more so I just assumed that the powder didn't like to be compressed. There are quite a few 9 major powders that aren't compressed using normal lengths for 9 major. Autocomp, HS6, and silhouette come to mind. Edited June 12, 2014 by DRichardson Link to comment Share on other sites More sharing options...
lee blackman Posted June 12, 2014 Share Posted June 12, 2014 I ran 7.3gr of Autocomp under a 125gr MG JHP thru my steel master (8lb & FLGR) at 1.090" COAL, was having problems with the nose of the bullet bumping the slide lock lever, so I backed it down to 1.050" COAL. At 1.090" there were no signs of overpressure. At 1.050" I had blown out primers and the brass Tulaammo marked cases blew out the bottom behind the feed ramp... Link to comment Share on other sites More sharing options...
BrianATL Posted June 12, 2014 Share Posted June 12, 2014 I ran 7.3gr of Autocomp under a 125gr MG JHP thru my steel master (8lb & FLGR) at 1.090" COAL, was having problems with the nose of the bullet bumping the slide lock lever, so I backed it down to 1.050" COAL. At 1.090" there were no signs of overpressure. At 1.050" I had blown out primers and the brass Tulaammo marked cases blew out the bottom behind the feed ramp... That is really short for a 9 major load Link to comment Share on other sites More sharing options...
jmorris Posted June 12, 2014 Share Posted June 12, 2014 (edited) I have never had any problems with compressed loads. Although I don't have many pistol loads that are compressed, many of my best rifle loads are compressed. I have only read about dangers of very small powder charges in "large" cases causing a detonation in that the primer starts a flame front at the reandorpneumatics the case and jumps over the rest of the powder layong at the bottom of the case and starting another one at the front of the case and the two collide causing a very high pressure. Like your engine "knocking" by an ignition from compression and another from the spark plug. Never had that happen in a fire arm though... Edited June 12, 2014 by jmorris Link to comment Share on other sites More sharing options...
kneelingatlas Posted June 12, 2014 Author Share Posted June 12, 2014 There are quite a few 9 major powders that aren't compressed using normal lengths for 9 major. Autocomp, HS6, and silhouette come to mind. What's a "normal length"? 1.125"? or 1.2"? My HS6 loads with 115s are most definitely compressed. Link to comment Share on other sites More sharing options...
kneelingatlas Posted June 12, 2014 Author Share Posted June 12, 2014 Only problem I've had with compressed loads was losing velocity when I added more powder. Haven't had that problem with my 38 Super open guns though, even when using N105. I too have seen this effect, but I don't think of it as dangerous, just the point at which there isn't enought oxygen in the case to get a complete burn. 10gr of SP2 gave me lower velocities than 9.5gr, but neither flattened the primers. Link to comment Share on other sites More sharing options...
peterthefish Posted June 12, 2014 Share Posted June 12, 2014 Only problem I've had with compressed loads was losing velocity when I added more powder. Haven't had that problem with my 38 Super open guns though, even when using N105.I too have seen this effect, but I don't think of it as dangerous, just the point at which there isn't enought oxygen in the case to get a complete burn. 10gr of SP2 gave me lower velocities than 9.5gr, but neither flattened the primers. Gunpowder does not rely on atmospheric oxygen for combustion. It is a fuel that contains an oxidizer. Decreasing velocities with increasing loads has nothing to do with inadequate oxygen in the case for a complete burn. Link to comment Share on other sites More sharing options...
EkuJustice Posted June 12, 2014 Share Posted June 12, 2014 There are quite a few 9 major powders that aren't compressed using normal lengths for 9 major. Autocomp, HS6, and silhouette come to mind.What's a "normal length"? 1.125"? or 1.2"?My HS6 loads with 115s are most definitely compressed. Depends on the gun but for a glock 1.155 is common and for an sti 1.16-1.17 is common. The shortest I have seen even for a glock is 1.145 Link to comment Share on other sites More sharing options...
Hi-Power Jack Posted June 12, 2014 Share Posted June 12, 2014 There are quite a few 9 major powders that aren't compressedWhat's a "normal length"?My HS6 loads with 115s are most definitely compressed. Depends on the gun but for a glock 1.155 is common and for an sti 1.16-1.17 is common. The shortest I have seen even for a glock is 1.145 +1. At least 1.145 - usually 1.16 - 1.17". Link to comment Share on other sites More sharing options...
kneelingatlas Posted June 12, 2014 Author Share Posted June 12, 2014 Gunpowder does not rely on atmospheric oxygen for combustion. It is a fuel that contains an oxidizer. Decreasing velocities with increasing loads has nothing to do with inadequate oxygen in the case for a complete burn. I did not know that, thanks Peter. Link to comment Share on other sites More sharing options...
kneelingatlas Posted June 12, 2014 Author Share Posted June 12, 2014 Depends on the gun but for a glock 1.155 is common and for an sti 1.16-1.17 is common. The shortest I have seen even for a glock is 1.145 I load in the 1.15"-1.16" range for my CZs/Tanfos. Link to comment Share on other sites More sharing options...
peterthefish Posted June 12, 2014 Share Posted June 12, 2014 Gunpowder does not rely on atmospheric oxygen for combustion. It is a fuel that contains an oxidizer. Decreasing velocities with increasing loads has nothing to do with inadequate oxygen in the case for a complete burn.I did not know that, thanks Peter. Thank you for all your posts on EAAs! Got me interested in a Hunter .45 that I picked up a while back. Now if I could just find a bolt on magwell and aluminum grips at reasonable prices I would be in heaven. Link to comment Share on other sites More sharing options...
Poppa Bear Posted June 12, 2014 Share Posted June 12, 2014 It seems to be very different from powder to powder. In my testing 3n38, and 4756 don't seem to mind being compressed, I fact to make major in 38 super with 4756 it has to be compressed. With long shot in 9major I had a issue where even when adding powder the velocity didn't increase and the velocity started to drop when I added some more so I just assumed that the powder didn't like to be compressed. There are quite a few 9 major powders that aren't compressed using normal lengths for 9 major. Autocomp, HS6, and silhouette come to mind. Longshot is a slow powder. If you increased your barrel length your velocity would increase. As it is all of the excess powder is burning up after the bullet has already left the barrel so the velocity cannot increase. Link to comment Share on other sites More sharing options...
DRichardson Posted June 13, 2014 Share Posted June 13, 2014 That makes sense. I never thought about that. Link to comment Share on other sites More sharing options...
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