[waktasz]

Well yeah but that isnt how its done & you know that.

Right, so what explains his backwards results?

 

[fredj338]

Right, so what explains his backwards results?

Perception is his reality or just Lack experience.

 

[CPTmorgan]

For IDPA 9mm & USPSA Prod, CO my vote is for 135g... they split the difference b/t 147g & 124g. 124s are fine, 135s are a bit softer but you're not waiting on the slide/sights like you will eventually do with 147g. 135g seems to drop falling steel about as well as 147g, haven't had any poppers that needed help.

 

[waktasz]

I love how people think they are waiting for the slide to cycle when shooting 147 grain bullets.

 

[Dragula426]

I have switched to the 124grainers....I was using the 115 grain, and I never had trouble dropping steel with them as long as I didn't hit low. The 124's seem a little better though. Recoil seems about the same.

 

[Gman3101]

I love how people think they are waiting for the slide to cycle when shooting 147 grain bullets.

It puzzles me too.

I went through over 30K of 147s in 2023 and have been shooting them for most of 2024.

Just started experimenting with 124s.

To me the difference is very negligible.

I still can't outsplit the slide with 147s.

The whole "it returns faster" doesn't make a lot of sense to me. I've seen zero difference in the spacing of my hits or split speed with the lighter bullet. Felt recoil is slightly more, but not enough to affect my shooting either way.

It's basically a wash for me. I've now got a die set for both, so whatever I happen to be able to by cheapest. I guess there's a small advantage in that 124s will be slightly cheaper per bullet, but again negligible. Probably just stick with the 147s I think.

 

[Biggfoot44.5]

What division, what gun?



Darn, I don't see a place on the chronograph report for energy.
At the same power factor, the MATHEMATICAL recoil is the same, the ballistic recoil is greater for light bullets because of the jet effect of their larger powder charge. An Open gun profits from a lot of powder, lot of gas blowing out through the loudener.

Felt recoil? Shoot and feel.

In this context , Kinetic Energy is irrelevant. Power Factor = Momentum by another name .

Simplest way of looking ( and measured by sanctioning body , and recieved downrange by target ) is :
Bullet Weight X Velocity .

More complex :
Bullet Weight Plus Powder Weight X Velocity

Physics Geek :
[Bullet Weight X Velocity] plus complex math regarding residual gas pressure at muzzle

Engineering Geek :
[ Bullet Weight X Velocity ] plus [ complex math regarding residual gas pressure at muzzle ] modified by [ really complex math about rate of slide acceleration , total slide energy , rate curve of recoil spring , and drag of internal components generally, and probably some more I'm not thinking of yet .]


Really Simple & Practical :

Just shoot different loads , and subjectively see what works for you , or even if there is any meaningful difference.

 

[1RoundEye]

That’s all a matter of preference. Some people like the “softer” recoil impulse of heavy slower bullets, and some people like the “snap” of lighter faster bullets.

If you can get your hands on a few hundred of each 115s, 124s, and 147s or the like, shoot them all back to back and see which one you like the best. You can also use a camera in slowmo and different recoil spring weights to see what combination actually shoots the flattest.

 

[Schrag4]

At the same power factor, lighter bullets have more energy (1/2 mv^2 and all that)

Chronograph doesn't report on felt recoil, and you're right, not only does a lighter bullet have more energy, but the powder has more energy and ejecta mass.

Two succinct posts that will be overlooked by the unwashed masses. Actual energy is a function of the square of velocity. This means that A) heavier bullets have a distinct advantage in the (flawed) PF calculation, and B) the relatively small mass of expanding gas from powder which easily reaches Mach 2+ contributes to actual energy in a significant way.

 

[Jim Watson]

Engineering Geek :
[ Bullet Weight X Velocity ] plus [ complex math regarding residual gas pressure at muzzle ] modified by [ really complex math about rate of slide acceleration , total slide energy , rate curve of recoil spring , and drag of internal components generally, and probably some more I'm not thinking of yet .]

You are taking me back to the 1960s and the Dean Drive, as "explained" by Davis Mechanics and the Fourth Law of Motion. Hey, maybe we could use a mini-Dean to convert the rotation of the bullet into added velocity.

If you can get your hands on a few hundred of each 115s, 124s, and 147s or the like, shoot them all back to back and see which one you like the best.

What a thought, empirical testing. That seems to have been largely replaced by asking a bunch of strangers on the internet.

the (flawed) PF calculation,

Early days, before consumer chronographs, power factor momentum was measured directly with a ballistic pendulum. Very simple, for Major, your load had to swing the pendulum at least as far as GI .45 Ball fired from a Commander or Star PD. The shorter barrel provided a margin of error in the shooter's favor. A friend reported seeing a manufactured pendulum sold as "Peter the Power Meter."

 

[Dg870]

The velocity of the slide plays a big part in felt recoil of an auto pistol. The snappy recoil of the 115s and the milder recoil of the 147s correspond with the 115s fast slide speed and the “waiting for the slide to go into battery with the 147.

 

[njl]

So my normal experience is that the heavier the bullet, the more felt recoil....I have been running 115gr bullets and wondering if I should be trying any of the others for less felt recoil and faster double taps.....Thoughts?

That may hold for factory ammo (where the PFs are wildly different), but if you reload and can keep the PF consistent, heavier bullets will tend to have less felt recoil. If you fired a factory 115gr 9mm round followed by one of my 147gr handloads, you'd probably think you'd had a squib on the second shot. That was my reaction the first time I mixed my 124gr and 147gr handloads.

 

[spencerspeech]

The balistic software suggests that the 105gr hybrid has slightly better wind drift performance at 1000yds than a 115 DTAC. I have shot the 6XC with both 105gr and 115gr bullets and they both performed well.

 

[NAZG26]

I was happy with 147. Cost me an extra ten bucks per 1000 for the bullets. Powder wise used 1.7 more grain per bullet with 115. All negligible to me. Was what I was comfortable with POA and recoil wise.

Carry 147 when I run run the Glocks as well so it's nice to be able to just reload one bullet for comp and training

 

[waktasz]

The balistic software suggests that the 105gr hybrid has slightly better wind drift performance at 1000yds than a 115 DTAC. I have shot the 6XC with both 105gr and 115gr bullets and they both performed well.

That's a pretty far shot for a 9mm

 

[njl]

IMO, best bullet weight comes down to a few questions.
1) How recoil sensitive are you?
2) How fast are you?

Some with really fast splits will complain that heavy bullets cycle the slide too slowly.
As mentioned in my previous post, the heavier the bullet (keeping PF constant), the less recoil you'll feel...so if you don't like recoil, go heavy.

I compromise and after starting out with 124gr, then switching to 147gr for a while, I settled on 135-138gr.

 

[Biggfoot44.5]

Early days, before consumer chronographs, power factor momentum was measured directly with a ballistic pendulum. Very simple, for Major, your load had to swing the pendulum at least as far as GI .45 Ball fired from a Commander or Star PD. The shorter barrel provided a margin of error in the shooter's favor.

It was specifically set for the Star PD , because at the time , it was the shortest bbl serious pistol in .45acp.

 

[CPTmorgan]

I love how people think they are waiting for the slide to cycle when shooting 147 grain bullets.

You cannot see what others see... everyone has different visual processing speeds:

The speed of sight: Individual variation in critical flicker fusion thresholds

The critical flicker fusion threshold is a psychophysical measure commonly used to quantify visual temporal resolution; the fastest rate at which a visual system can discriminate visual signals. Critical flicker fusion thresholds vary substantially among species, reflecting different ecological...

journals.plos.org

Just like nerve conduction studies... you can measure the time it takes for a neurological impulse to travel from brain to trigger finger, I've had it done... you can measure "individual variation in critical flicker thresholds" too.
Any given shooter's subjective visual experience of front sight speed is going to be different.
Some folks like to watch the empty brass coming out of the pistol, too... most don't.

 

[waktasz]

I've never heard a high level shooter say they are waiting for the slide to cycle. They might say it feels a certain way or maybe even feels sluggish (ever shoot 160gr 9mm or 200gr minor 40? lol) but waiting for the slide to cycle is nonsense.

 

[CPTmorgan]

I've never heard a high level shooter say they are waiting for the slide to cycle. They might say it feels a certain way or maybe even feels sluggish (ever shoot 160gr 9mm or 200gr minor 40? lol) but waiting for the slide to cycle is nonsense.

Yes, I've loaded a test batch of 160g to try... didn't like them. We had 8 kids at Nationals shooting 9mm 1911s this year, and they do best when shooting 147g minor loads... the kids that tried 124g struggled with recoil; only one of the 8 kids is stout, the others are all pretty average build. We struggled with 1911 this year and finished 3rd. The match ammo was syntech 130g and it was actually pretty nice, not a big difference between that and 147g. Personally I loaded 2500 Blue 135g this month and really like 135 whether Blues, RMR, J-Ames, they're all great... I find the Blues easiest to load.