Originally Posted by
garyb
I know there are not many 40cal IDPA competitors out there AND I am NOT trying to start a debate of any kind. I reload my own 40 ammo for IDPA, but have limited experience with sampling different powders and bullet weights. I am starting to get into it. Recently on another thread, a gentleman made a point about using 180gr bullets for the 40S&W with lighter powder loads because it had less muzzle flip. I currently load 165gr.
I am wondering if anyone out there has good knowledge/experience with reloading and IDPA, that could tell me more about the relationship between bullet weight and muzzle flip. I pose this question understanding that there are numerous variables and considerations that must be considered, so let's try to keep it simple. Let's assume we are comparing the same powder type and the only variables are the 180 vs 165 bullet with light enough loads to make either bullet cycle in a semi. I would have expected that a heavier bullet would contribute to more muzzle flip which translates to a longer recovery for the next shot. Obviously in competition, the goal is to get your next shot off as quickly as possible and less muzzle flip is generally better. It appears that the use of 180gr bullets (vs 165gr) uses a smaller powder charge (with the same powder being used). Does the 180gr with less powder reduce the muzzle flip or increase it (vs a lighter bullet with more powder) and both loads (180 vs 165) being enough to cycle the semi?
I hope I have made the question easy enough to understand and I know this question runs some risk of stirring the pot. That is not my intention, because I am hopeful that someone out there can make GOOD sense of this for me....if that is possible. Thanks a bunch.
Hi Gary, you're not the only one dipping his toe into IDPA with a 40. I have run a few matches with my T running both 165 gr and 180 gr Raniers on top of their respective max loads of HP-38. I haven't chrono'ed either load but I'm guessing they both come close to or exceed major. I'm in the same boat as you and planning on making some IDPA loads as soon as I can get bullets. I had recommendations to go to a faster powder such as tightgroup by some of the locals. The reason given was to achieve a sharper pressure peak. There are alot of folks using HP-38/Win231 that are perfectly happy, too. I also read somewhere that the 165 gr was the ideal bullet weight for 40. The argument basically came down to powder capacity under the bullet and being able to achieve supersonic speeds. Not what we are interested in for IDPA.
Good point by the previous poster regarding lighter bullets and faster slide speeds, that may be part of the phantom worth chasing. Matching the Power Factor of your choice of SD ammo might be worth considering, too. I loaded up my current batch of 40 with the intent of making range practice an exercise in hand and arm strength. Dummy me for shooting it in IDPA matches.
The point on heavier bullets comes from A=1/2MVV or the formula for acceleration. Heavier bullets travel at slower velocities so that reduction is to the square while lighter bullets at faster speeds is not. The theory is that at the same power factor, heavier bullets yield less acceleration (recoil). BTW, Power Factor is just another name for momentum. So we have to maintain the momentum while reducing the acceleration and still cycle the pistol reliably. Fun Fun!
Just some thoughts on recoil, the mass of the pistol you are firing also weighs into the recoil as does your grip height. Stance is another neglected area, but you probably know these tricks
I don't worry about the guys running their 9's faster than me, I know I'm putting out more stopping power. Just one in the 0 down will do it 89% of the time. IDPA should add a 0 down area just below the belt buckle.
Last edited by Kahrdriver64; 04-11-2013 at 01:50 PM.
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