Muzzle Flip vs Bullet Weight

[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.

[CJB]

Lighter bullets will generally tend to shoot lower, have less flip due to recoil.

However.... there is a LOT to it, and there is also a bit of a balancing point too where weight vs speed begin to do weird things with flip.

Lower recoiling lighter bullets are usually what you'll see on competitors benches - unless - its something like silhouette... where all bets are off.

[HighLander51]

The power floor for IDPA SSP and ESP is 125,000 (bullet weight times muzzle velocity) and slide speed. So you want to load your 165 grain 40S&W to run just over 760 feet per second or 180's to just over 700 fps. The heavier bullet going slower will have less recoil event. There is not much of a difference in slide speed between these 40S&W loads, unlike a 9mm, so you are going to better off running the 180's. I run 124 grain 9mm out of my G34 going about 1,200 fps (149 floor, well above minimum) or 147's going just over 850 fps (minimum floor). The 147 has much less of a recoil event, but the 124's cycle the slide much faster. It really depends on which load gives you the most confidence.

A lighter bullet with the same powder charge will go faster, it's just physics.

[garyb]

The power floor for IDPA SSP and ESP is 125,000 (bullet weight times muzzle velocity) and slide speed. So you want to load your 165 grain 40S&W to run just over 760 feet per second or 180's to just over 700 fps. The heavier bullet going slower will have less recoil event. There is not much of a difference in slide speed between these 40S&W loads, unlike a 9mm, so you are going to better off running the 180's. I run 124 grain 9mm out of my G34 going about 1,200 fps (149 floor, well above minimum) or 147's going just over 850 fps (minimum floor). The 147 has much less of a recoil event, but the 124's cycle the slide much faster. It really depends on which load gives you the most confidence.

A lighter bullet with the same powder charge will go faster, it's just physics.

Thanks for the info. You make alot of good sense and I've confirmed what you said to be true. Thanks.

[Kahrdriver64]

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.:D

[AIRret]

Keep talking folks, I find this extremelyyyyyyyy!! interesting.
Reloading is fun and the manipulation of velocity, bullet weight, and recoil is amazing!!
But then again I taught physics. Which was crazy because I had to work as hard as my students everyday!!!!

[Kahrdriver64]

I agree with you. After I thought about the OPs original intent of faster follow up shots, we have to put time considerations in play. The ideal would be PF above 125, shortest duration of recoil, and manageable total recoil. This ideal snappy load should put the shooter back into battery the fastest.

So maybe the lightest bullet, fastest powder, and a magnum primer to light it off might be worth playing with,too. Bullet drop would a lot less for the longer shots.

So many options and no bullets in the cubbard.

[Barth]

I don't reload or shoot competition.
But I am very bored.
And I did stay at a Holiday Inn Express last night - LOL!

I have found that my firearms are to some extent unique.
I really need to try out various ammo weight, power and manufactures for myself.
To see how that particular firearm and ammo combination, in my hands, performs.

Most of my guns will favor, i.e. group better with, a particular weight,
and sometimes a particular manufacturer's, ammo.

As for felt recoil?
A lot seems to have to do with platform ergonomics as well as bullet weight.

In my full size 40 S&W guns it's hard for me to tell the difference.
Maybe if I was recording split times It might be noticeable.

But with factory ammo, in my MK40 Elite, sub sonic 180 gr provides much faster follow up shots than 155/165 gr.

For what it's worth...

[garyb]

I've found that 165gr FMJ over 5.5 to 5.7 gr of Longshot works extremely well in my PM40 for IDPA. I am prepared to experiment a bit with 180gr FMJ's, as I have learned that the recoil will be less....but perhaps the slide will work a bit slower too. Longshot powder is an excellent powder for 40cal....clean, safe, accurate. I just picked up another 5 lbs and plan to compare it to Power Pistol in the future.

[dkmatthews]

The .40S&W cartridge is what I started with and what I learned to reload with. I'm no scientist or mathematician or physicist or whatever, but I can tell you that my experience says that the perception of flip comes from the cycling of the slide at a violently high rate of speed. Based on that, I avoid any bullets weighing less than 180 grains, even in commercial ammo, because the loads generally create a very fast round and a very fast slide cycle.

I have been thrilled with loading 180 grain Berry's or other copper plated bullets over 7.8 grains of Blue Dot powder. Anything less than 6.8 grains of powder will make my Glock 22 into a single shot pistol. I haven't loaded a 180 grain bullet with more than 8.5 grains of Blue Dot, simply because the recoil/flip/slide cycle rate starts to get too strong and the accuracy suffers.

[garyb]

[QUOTE=dkmatthews;257911] I avoid any bullets weighing less than 180 grains, even in commercial ammo, because the loads generally create a very fast round and a very fast slide cycle.

QUOTE]

I agree and this is the reason I am going toward the 180gr for IDPA. I have learned that this bullet provides an optimal slide action and low recoil.

[garyb]

Bongo Boy once explained the issue to me. To produce the same power factor, a lighter bullet must be pushed faster and with a higher muzzle energy. Muzzle energy contributes to recoil. The objective is to reduce recoil / muzzle flip so that you can stay on target for the next shot in competition. If going for a lower recoil for competition, push a heavier bullet as slow as possible....but only as slow as it can cycle and still hit the target fast enough to be able to push to the next target. In other words, if the slow bullet does not have the energy to cycle....no good. If the slow bullet is too slow for a highly competitive shooter who shoots very fast....no good. It becomes a balance. The powder puff charge must cycle and the bullet must hit fast enough to allow the shooter to be fast enough to move on to the next target. Obviously there are technical details involved to prove this point, but this is the basic concept. dkmatthews, you are right on target too. When you start to get into this for competition, it is very interesting stuff. Some guys reduce their recoil spring so they can shoot even puffier loads. I am not interested in heading in that direction, but I understand what they are doing and why.