Do I need to worry about making Minor Power factor with factory 9mm?

[aztecdriver]

Not really enough to worry about.

Yeah. I'm going to disagree with that. The barrel length dictates how long the projectile is under acceleration. I could get into it but im on vacation in Florida and rather than be "that guy" I'll let someone else argue it.

[aztecdriver]

And, now that I think about it hexagonal rifling has a better seal. Which is one reason leading in Glocks is a BadThing. Because of better seal, same amount of gas - muzzle velocity should increase not decrease if it was solely rifling. Length definitely matters more.

[Thomas H]

Actually the numbers represent the type of barrel rifling.

Really. So I guess the .51 inch difference in length means nothing. In that case i assume the approx .8 inch difference from the 17 to the 34 will shoot the same ammo the same velocity. It's the same rifling and headspacing?

Not really enough to worry about.

Hm. Well, I've used a chrono on three different Glock 19s at the same time using the same set of reloaded ammunition, and out of 10-shot data sets for each, gotten numbers with a standard deviation of 6.7 ft/sec using the entire data set.

Ran the same ammo (on the same day) through two different Glock 34s. The 34 data set (entire) had a standard deviation of 7.1 ft/sec.

And the 34 data was consistently slightly over 21 ft/sec more than the 19 data.

Speaking as a physics person, and someone who has actually taken data---all else being relatively equal (for example, pistols of the same make), longer barrels will consistently give you greater velocity. Yes, the G17 and G34 are similar. Nonetheless, you are going to get an increase in velocity. Not as much as with a G19, but you will still see an increase.

I could quote numerous other people who actually took data for this sort of comparison, but I'm not going to bother. Believe what you like.

...in the end, you should chrono your loads with the gun you are going to use, and give yourself a comfortable cushion to make certain you will make the level (major or minor) that you wish.

I shoot Production, and I use 147 gr Montana Gold bullets. I normally load to about a 135 PF from my G34, because it isn't if the recoil is much different compared to a 130 PF, and I want to make absolutely sure that no matter what the weather/temperature/pressure/whims of a deity, I'll make minor.

Chrono your load. Always!

[92fs]

UMC is pretty close but it depends on the gun- some barrels are faster than others. Don't ever assume....

<div><br></div><div>If you don't make MINOR- you don't get bumped to Open you get a DQ.</div>

No, you just shoot for no score or recognition. Definitely not a DQ.

Appdx C2 39

If the resultant power factor fails to meet the minimum power factor floor

for the relevant Division, the competitor may continue shooting the match,

but not for score or match recognition.

So this rule means that any ammo used be hand loaded?

Actually, what it means that your ammo and gun combination must meet the required minimum power factor as you have declared when you sign up for the match, as measured by the chronograph procedure. The rules don't make a distinction as to hand load or factory - for the reason one could take reloads, pretty them up and stick them in factory boxes and claim "I'm shooting factory". They're both treated the same at the match.

Every competitor must validate their ammo shoots through their gun at the required power factor. What we are suggesting to everyone is don't make the assumption that just because it is factory produced ammunition that it will shoot the required power factor. Many will with room to spare, but it depends on the gun, length of barrel, the manufacturer's variances and whole host of factors down to the weather an even your altitude above sea level on how ammo will perform. It's best to validate your gun and ammo configuration with a chronograph than to make that assumption.

I got 135 from my G34 using UMC at Smith & Wesson Indoor Nats.

[crispy]

Just chrono'd some cheap factory 9mm today. All 115 grain. Ambient temp was 90+ degrees.

Out of a 5" S&W M&P

WWB averaged 1213.8 fps for PF of 139.5.

S&B averaged 1141.0 fps for PF of 131.2.

Federal Champion averaged 1104.2 fps for PF of 126.9.

Some of the Federal was under 1087 fps.

Just for the heck of it I shot the same ammo through my Ruger SR9c with a 3.5" barrel. I wanted to see for myself how much difference the length of barrel would make. Results were expected but interesting nonetheless.

WWB averaged 1168.0 fps for PF of 134.3.

Federal Champion averaged 1065.3 fps for PF of 122.5.

The additional 1.5" of barrel made a 3.9% difference with the WWB and a 3.6% difference with the Federal.

The takeaway from all of this is that although the Federal would probably make it with a 5" barrel, shooting it through a 4.25" or 4" barrel would be risky. Don't do it.

Since WWB is cheap and plentiful at Walmart, that's what I'll be shooting at the State match.

[beltjones]

I did some testing of my own out of my G34 and again out of a Shadow. It was around 90 degrees and sunny.

G34:

UMC averaged 1155.6 for PF of 132.9.

Magtech averaged 1183 for PF of 136.0.

Federal Champion averaged 1191.0 for PF of 137.0.

WWB averaged 1212.7 for PF of 139.5.

Shadow:

UMC averaged 1123 for PF 129.1.

Magtech averaged 1147 for PF 131.9.

Federal Champion averaged 1161 for PF 133.5.

WWB averaged 1167 for PF 134.2

I think the lesson is that there are factory ammo choices that will make minor, but a lot depends on your gun. You really can't expect every ammo to make minor out of every gun, and just like those who reload, you may have to do some experimenting to see what load works best for you.

[Craig N]

If you're using Federal Champion, that stuff is known to be fairly puny. I'm guessing not even 125PF.

Definitely want to chrono, I target my reloads at 130-132, just to make sure.

Sorry to necro this thread but I just put some Federal Champion in my range boxes and the MV on the back is 1075 and with a 115 grain bullet its only 123.