9mm velocity question.

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Jeff H

New member
So, in the next week or two I'm going to start loading up my supply of 9mm for next season's shooting games (I'm down to my last box of 250 :eek: ). Probably looking at 3000 or so. The problem is that next year, I'm thinking of getting into USPSA so I need to be conscious of minor power factor. My current loads are rather soft shooting so I doubt they make minor, but since I don't have a chrono, I don't know for sure.

Out of a 4" gun, shooting 125gr lead round nose bullets and Win231 powder, does anyone have data on what load will chrono above 1000fps?
 
S

Sevens

New member
Jeff, someone could give you a load with those that chronos WELL above 1000 FPS, but you may very well end up with a load that produces a lot more recoil than you want/need for competition. And if someone suggests a load where it goes just over 1000 for them... and yet it doesn't when launched from your pistol, you'll get disqualified, no?

Get a chrono or borrow one. I can't imagine any possible way to do this right without one.
 
U

Unclenick

Staff
If you go to Hodgdon's load data site, they say a 125 grain LCN (Lead Conical Nose; same as Truncated Cone, AFAIK) bullet seated to 1.125" COL in Winchester brass over a CCI 500 primer and loaded with 3.9 grains of 231 will get 1009 fps from a 4" tube. That's their starting load. Their maximum load is 4.4 grains, for which they claim 1086 fps.

Several points about that load:

  1. Normally velocity goes up in rough proportion to powder charge. If they got 1009 fps with 3.9 grains, they should get somewhere around 1138 fps from 4.4 grains, or, if they got 1086 with 4.4 grains, they should get somewhere around 963 fps with 3.9 grains. So, right away I am alerted to the fact this component combination wasn't well behaved for them.

  2. All components you use that are different from the ones they used will affect the load's performance. Change the case, primer, or bullet shape and hardness (even if the weight is the same), and the load's performance will change; perhaps significantly, perhaps not. Allow at least 5% change being possible for any one component being different. This even includes that the lot number on the can of powder you bought is different. That makes the powder a different component. Though it is usually not hugely different, every once in awhile a lot is more different than you expect. The component variation is one reason you always start with the manual's bottom load and work up while being alert for pressure signs.

  3. The above goes double for the gun itself. They will have used a SAAMI spec pressure and velocity barrel which has tight chamber dimensions and nominal bore dimensions. Chances are your actual gun will get lower pressure and velocity than they did because your chamber is likely to be looser than theirs, but there's no guarantee that will be true or that your bore isn't tighter than theirs. That's another reason for always starting with the bottom load and working up.

  4. If you don't have the same length LCN bullet they used, your results will differ, especially as to pressure. This is because the amount of space the powder starts burning in affects peak pressure value. Using the same bullet weight is important, but you also need the same seating depth of the bullet base into the case as well the same bullet hardness and ogive length (so jump to the throat is the same) in order to get exact matching performance.
So (and most especially with a load combination that isn't well-behaved) all you can say about the published load data is it represents what these loads did for Hodgdon on one particular day with one particular gun.

Bottom line, if you want to know what your actual components do in your actual gun, you'll want to do as Sevens suggests and get the use of a chronograph. Sorry there's no easy substitute.
 
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W

WESHOOT2

New member
Absolutely.
I use Penn Bullets 125g LRN.
To ensure Minor PF I suggest:
-5.3g Ramshot Silhouette
-5.4g Alliant Power Pistol

If you have a 'slow' gun you can readily increase either to 5.6g.
 
D

dlb435

New member
First, a chrono is not that expensive. You can order one from WalMart and have it delivered to your local store for free.
Second, the load data published by the different powder companies is very accurate.
Third, many ranges have chronos to rent for only a few dollars. Make up some loads at different powder charges and test them.
Forth, getting the loads to the minimum charge posible is not all that important. What is important is consistant loads. Factory ammo can vary a lot shot to shot. Well made hand loads can do much better. Put your efforts in to making each load a perfect as possible and that will pay off much better.
 
E

engineermike

Moderator
Boy, you got that right. I got bored the other day and started de-priming and sizing some 9mm brass. I took out the trusty calipers and measured the cases and found a few at .750 and a few at .747, a few at .745 and a few at .740. My Hornady book reads that they trimed to .750. So how much does the compression change from case to case? No wonder factory loads are sometimes all over the place. No telling how much the powder measures are off. :eek:
 
S

Sevens

New member
Case length in a straight-wall (or lightly tapered, as is 9mm) pistol case really won't make any difference in pressure -- the COAL and internal space is roughly the same no matter the length of the case. The seating stem pushes the bullet in to place... the case is coming up under the pressure of the ram.

Personally, I separate by headstamps and I don't know if that gives me any edge in repeatability, but I figure it can't hurt.

But the COAL of the loaded round won't vary due to length of case.
 
A

Adamantium

New member
Absolutely.
I use Penn Bullets 125g LRN.
To ensure Minor PF I suggest:
-5.3g Ramshot Silhouette

If you have a 'slow' gun you can readily increase either to 5.6g.
Click to expand...

What manual are you quoting? Ramshot lists 5.0 as max for that load.
 
S

Sevens

New member
And all this time I thought length mattered?:rolleyes:
Guess I will have to stop crimping...
Click to expand...
With the "roll eyes" smiley in there, I'm not quite sure about the nature of your reply...

In any case, trimming straight wall revolver rounds isn't a bad idea because it allows you to roll crimp consistently in exactly the same place. I do it myself for .44 Mag loads built for a Desert Eagle.

When taper crimping, it doesn't really matter if the case lengths are exactly the same or not. But all I was trying to say is that even if you took two similar pieces of, say, 9mm, and trimmed the heck out of one of them -- and then seated the same bullet in them using the same shell holder, press and seating die, adjusted exactly the same and loaded them back to back...

You could measure them and find that they'd be the same overall length even with the wildly different case lengths. (assuming the bullets are precise and your seating stem works well with the bullet profile and your equipment is good at making consistent ammo.

It's just simply that the bullet is being pushed from one end and the case head is being pushed from the other end and the length of the case really isn't going to be involved with the measured overall length of the round.

Lee has said themselves, when asked why on earth they sell trimming tools for 9mm and .45 Automatic when nobody really trims these. Their reply... "we makes those particular ones because folks have asked for them." I guess they didn't come out and say "ummm, yeah, there's no real tangible use for these but we still make 'em" but that's kinda the drift I've gotten.
 
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WESHOOT2

New member
my own

I have some experience with its predecessor WAP (I noticed that I've burned though 11 3lb cans in just the last five or six years).

I have also used a bit of Power Pistol in 9x19.

I think it safe to say I've made a great deal of safe ammo in my past.
 
S

Sevens

New member
Wow, I've never heard of any smokeless powder marketed in a 3-lb can.
Maybe I haven't been looking!

I'm still annoyed that Power Pistol isn't offered in an 8-lb'er. I think I could save a couple bucks over the two 4-pounders I buy.
 
E

engineermike

Moderator
Well you see Stevens, that is what bothers me. Most here say that 9mm has the most pressure spikes with just about any variation to the loading process. Then there are those that come up and say that many variables don't matter. :rolleyes: It either is or it isn't.
 
Z

zxcvbob

New member
Variations in the length of the brass don't matter much. It only affects the crimp. Variations in the overall length can matter a great deal because that also changes the seating depth and can cause the pressure to skyrocket.
 
S

Sevens

New member
Mike, step back a second and get a whiff of fresh air.

If your COAL is in a wide variance, you've got trouble ahead.
C O A L being cartridge over all length, the measurement of the entire loaded round. If you are using exactly the same bullets across 5 loaded rounds (and all of those BULLETS have the same length from base to tip) and all of them are loaded in to brass and ONE of those loaded rounds is well shorter than the others, what you have is a loaded 9mm with less internal space for the powder to burn and the gas to expand. That reduced internal space does indeed rocket up the pressure and when we are talking about a 35,000 PSI cartridge that's already tiny as hell, then yes we are worried about skyrocketing pressure.

However!

The length of the empty, unloaded brass case really has very little bearing on how l-o-n-g the loaded round is going to measure when you consider how the bullet is physically being placed in to the brass.

When a press is forcing a bullet in to a piece of charged brass, it doesn't know or care where the case mouth ends. It only knows that the case is being pushed from the case head and that the die is holding the bullet steady by it's tip or ogive.

This would be much easier to show... than to write about.

Your press is set to push downward until the ram reaches the end of it's stroke. The bullet is going to be seated to the same depth every time as long as you swing that press handle the full stroke.

If your brass is a bit longer, but you throw the lever to it's full max each time, the COAL of your loaded rounds is still going to be the same even if you had some long pieces of empty brass or some short ones.
---------------------------------------

I'm running out of ways to try and describe this any better. If you want to think that I'm trying to be contrary to what we typically suggest around here, or if you want to try and assume that I'm simply feeding you a line of crap and attempting to trip you up, that's going to be all on you.

But the facts are the same... loaded COAL variances matter a lot in 9mm. Lengths of unloaded 9mm brass? Doesn't matter a helluva lot.
 
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