Velocities and "Power Floor"

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rainbowbob

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I'm new to IDPA and have discovered in the rules that a minimum power floor is required for the ammo used.

According to the book, power floor is calculated by multiplying the bullet weight by the muzzle velocity.

For a stock service revolver like my S&W .38 M-15 w/4" barrel, the minimum power floor is 125,000.

For example, that means a 148 grain bullet would need a muzzle velocity of appx 850 ft/sec to qualify.

Short of doing a chrono, is there any way to know whether my factory loads are good to go?
 
You can use the factory published number as a guide, but a chrono is best. If you're just starting out, just go and shoot some local matches and start meeting people. Chances are someone has a chrono; it's not unheard of for someone to bring one to a practice session.

I'm not sure how IDPA matches are run, but in local IPSC matches chronographing ammo at local weekend matches is rare. Different story for state/regional championships, of course. As long as it sounds good and knocks over poppers, you are generally good.
 
Do you know where I find factory published ft/sec numbers on any particular ammo out of any specific barrel length? I've googled it but the info so far is sketchy and inconsistent.
 
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I agree that for club matches, chronographing ammo is rare.

However, major/sanctioned matches are a different story and 4 of the last 5 or so that I've shot did chrono all ammo.

And they disqualified a LOT more shooters than you'd expect. (In fact, at one match the Match Director DQ'd his own wife for not making power floor...and he'd loaded her ammo!)

One subject of much discussion lately in IDPA circles is that there is very little -- if any -- factory .38 Special ammo that does hit 125,000. I've even heard that a lot of "+P" stuff isn't getting there, but I've not checked any myself.

It is also important to check it in YOUR gun, not off a chart somewhere. Each gun, and revolvers especially, will shoot the same ammo at slightly different velocities, and it can easily be enough to matter.

At a local match, you're fine because almost no one chrono's ammo at club matches. At a big match, you're just wasting your entry fee if you don't check your ammo over a chrono the week before just to be sure.

(Remember, your velocities often will change with the ambient temperature. If you're close to the line, watch out!)

-Sam
 
That is a very interesting reply, Sam - thanks. Now I've got to find someone with a chrono. There is a state match this weekend at the local club. I'm not entered (haven't classified yet) - but I wonder if they'd do it for me. They may be kinda busy though, huh?


Jeff, the link you provide is a good resource, but they only tested the lighter JHP rounds.
 
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They may be kinda busy though, huh?

Wow. Kinda.

If you know the guys who will be working the chrono that day and can ask for a favor, they might run you through if they've finished up, but they've got a lot to do that day.

They'll have to shoot at least three rounds through the screens for each of 150 or so shooters, and calculate the PF and record it, and do re-tests if folks fail on the first go-round, with guns in at least four or five calibers (and if an odd duck like me shows up shooting an unusual cartridge, they've got to track down a test gun to shoot that ammo through, or pull the shooter off the line and use his gun)...ETC.

Most match directors and staff really don't want folks who aren't shooting the match or working the match wandering around the property on match day. Just one more thing to worry about when they're already stressed to the edge.

Now, if you've got some free time this weekend and can go offer to help out as a staff "extra" for a day, that could curry you some real favors, and you'd meet some real friendly faces who would be thrilled to help you get started in the sport.

I know $100 for a chrono is a sizable chunk of money, and you might not want to buy one yourself. But you'll probably be reloading before too long and you'll definitely want it then. Otherwise, you should be visiting the local IPDA club for their practice sessions and any of those guys would be happy to set up his chrono for you -- as long as you've demonstrated enough proficiency not to shoot it! ;)

-Sam
 
Otherwise, you should be visiting the local IPDA club for their practice sessions and any of those guys would be happy to set up his chrono for you...

You're probably right about someone at the practice sessions having a chrono. I'll ask around.

I also realize things may be kinda hectic at the state match. I would only ask if it seemed appropriate (and probably not).

I would like to go and watch my buddy shoot. I figure it would be a great watch and learn opportunity. As a member of the range and of IDPA, I can't imagine they'd boot me out.
 
I would like to go and watch my buddy shoot. I figure it would be a great watch and learn opportunity. As a member of the range and of IDPA, I can't imagine they'd boot me out.

No probably not. Especially if you're there with one of the competitors. It's not uncommon to have a friend or spouse tag along with a shooter. Keep your eyes and ears on and if you can stick close by your buddy's squad rather than just wondering around that would probably be polite. I'm sure you'll be fine.

Have fun!

-Sam
 
Thanks for the suggestions, Sam. If I go, I'll hang with my friend and his squad, maybe offer to tape and pick up brass.
 
If I go, I'll hang with my friend and his squad, maybe offer to tape and pick up brass.

Definitely help paste! But please, please be attentive to the comments of the Safety Officer and Scorekeeper. You can't IMAGINE how much of a boob you'll feel like if you inadvertently paste a target before the SO has officially scored it. In a major match (and really, by rights, in any match) that's an automatic re-shoot, and neither the competitors nor the match officials look kindly on such things. Not that you should be hesitant to help out...just make SURE you've gotten the o.k. from the SO (every time) before you paste any holes. Sounds silly, but I've seen it happen many, many times.

As far as brass goes, watch your step there too. MDs seem to be getting stricter about the "lost brass" match idea. At the last major match I shot and SO'd, the MD made all shooters and staff aware that any competitor seen picking up brass would be immediately disqualified. Period. At best, brass fetching can be seen as an unnecessary delay of the match, as well as taking folk's attention off of pasting. And in a lot of cases the MD's consider the right to retrieve spent brass at the end of competition as one of the (very few) perks belonging to the SOs who volunteered so much time and effort to set up and run the stage. If you don't see anyone picking up brass, don't touch it. Trust me, it will get picked up in due time.

Have fun, talk to as many people as you can (after they finish their strings, of course) and pay as much attention as you can to the gun-handling and footwork of the better competitors. Some of the biggest gains you can make early on are in simply figuring out how the fast guys move their guns, execute their reloads, work with cover, and how they choose to maneuver between and in relation to the firing points.

Let us know how it goes and what you get to see!

-Sam
 
One subject of much discussion lately in IDPA circles is that there is very little -- if any -- factory .38 Special ammo that does hit 125,000. I've even heard that a lot of "+P" stuff isn't getting there, but I've not checked any myself.

This is true and there is nothing new about it. Back in 2001, I bought 500 rds of PMC 150 grain FMJ .38 Special. I'd previously won a State Title in all divisions but revolver, so I thought I'd round it out.

I chrono'd the ammo shortly before the match and found it wasn't even close to Power Factor. I didn't have time to load any or find anything else, so I bought some Winchester White Box .357 110 grain JHP's. Now THOSE were a pretty major "minor" power factor!

Even tho I set a hay bale on fire with the muzzle flash, I managed to win that 4th Division State title.

(Walt Rauch told me to write up the story and they'd run it in the Tac Journal........ I'm still waiting....)
 
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