Question on 9mm HP COL

[ulflyer]

I've shot several boxes of Freedom XTP new ammo in my Kahr CW9 and it works very well. Since I plan to reload 9mm for the first time shortly, I've begun
gathering data and noticed a lot of variance in the COL of HP and Jacketed.

The Freedom COL measured 1.064. Looking at various loading charts I see 1.090, .125 and .140 for jacketed HP.

The bullets I will be using are ZERO brand 115gr HP. I'm uncertain as to what
COL to use. Should I pull an XTP bullet and measure it against the Zero HP? Or perhaps seat the bullet long and use the plunk test to determine best COL?

I'm inclined to think a shorter COL would be best since the brass is
a mix of headspace and not trimmed.

Suggestions please.

 

[Walkalong]

The area of 1.060 to 1.065 is a good place to start with a JHP in 9MM. Try a few and see if your gun likes them. Try more if it does. Maybe tweak the OAL up and down a little to see how it affects feeding. You should have an answer by then. Brass length has nothing to do with it.

 

[jwalts27]

Do what Walkalong said. Different profile HP's feed differently in various guns. A Federal HST may feed fine but a plated HP might hang up and vise versa.

 

[Potatohead]

The Zero gal told me that it was ok to sub Speer bullet COLs for Zero.

I generally run 9mm in the 1.10-1.15" range.

 

[Walkalong]

HP's PH?

 

[Gadawg88]

For what it is worth, I load my Hornady 9mm XTPs at 1.10.

 

[Smj]

COAL in 9mm.....

I load only Montana Gold 115 and 124 gr HPs. The OAL I do depends on the barrel of the gun I'm loading for. So I make a dummy round, [no powder/primer] and start long. If it hits the lands of the barrel keep seating deeper until you get that nice "Thunk" sound when you drop it in the barrel. Then I shoot for .002"-.005" clearance between bullet shoulder and barrel lands. Of course proper feeding is a necessity so you may need to work with that too. I've not had feeding issues with any COAL in any of our 9mm guns and I load COALs from 1.070" to 1.125". One gun, SR9, even at 1.125"+ doesn't hit the lands, so I load it at what ever the book says. Whether or not bullet shoulder to barrel lands has a big influence on accuracy in a hand gun is a maybe I think. But I believe having the bullet shoulder jammed into the lands may lead to pressure spikes, so that's something to watch for.

You should also take into account that pressure may become an issue if you are using a COAL well shorter than the load data shows.

Sorry for being so long winded here.

Smj

 

[ulflyer]

Thanks a lot guys for the feedback. I think I have enough solid info to begin working up a load soon. SMJ, I like your way of using a dummy round. Makes sense to me.

Can't wait till my Dillon Conversion Kit gets here. I have everything else, Bullseye, 231, and Clays, Win primers, mixed brand brass. I think I'll start with BE as theres a lot of loading data for it, although I really like the "soft" feel of Clays in 45acp and want to try that later on.

One thing that threw me is the COL's of factory metal jacketed. Four brands measured
1.154 for three of them and one at 1.140. These seem so far off from the HP bullets. This length also worked well in the Kahr.

 

[gamestalker]

First off, lets address case preparation, and mixed head stamp as it applies to oal. For all practical purpose, oal does not correlate to whether or not the brass has been trimmed. It actually has no bearing what so ever.

Regarding mixed head stamps, this also has little to do with oal. About the only factor would be case volume variations, which can have some degree of effect on pressures, but more so if the load is near the top end. But we don't use pressures as a means of determining the correct oal, but rather acknowledge that pressures are effected by increasing or decreasing oal. So as an example, if a reloader were to shorten the oal of an already worked up load, pressures are certain to rise, the reverse would apply if oal was increased. OAL is a pre-determined specification as per the plunk test, to which the powder charge will be fashioned around.

To find the best functioning oal the plunk test is what would apply here. Once you've found the plunked oal that fits the magazine, clears the lands, and feeds properly, all that's left is test firing to be sure they will feed reliably. I would like to add, if the plunk exceeds SAAMI max oal, then decrease oal to within that parameter.

I hope I shed some light on this for you.

GS

 

[ulflyer]

GS: Thanks for comprehensive answer. I feel much better informed now and ready to begin loading soon.

 

[Starter52]

FYI a reminder, if your overall length is too long the round will not fit smoothly into the gun's magazine.

It is not enough to just drop a round into the chamber; remember to try a few through the magazine.

 

[vaalpens]

I would like to add, if the plunk exceeds SAAMI max oal, then decrease oal to within that parameter.

gamestalker, is your statement above correct, or are there some wiggle room? The reason why I am asking is that I currently load my 40S&W loads with an OAL of 1.142", which is over the 1.135" MAX OAL.

 

[gamestalker]

Well, the reason SAAMI specifications determining max oal exist, is to provide a common manufacturing guideline that will guarantee all factory ammunition will fit every firearm. But there are also some others reasons, such as providing enough bullet shank inside the case to assure there will be no neck tension problems. And of course, there is also internal ballistics that are factored into this.

So to answer your question to the best of my ability, if you are not going to run the ammo in any other firearm, or those which have ot been plunked to that oal, and neck tension is acceptable as per the bench test and pull test, you can use the longer oal that exceeds SAAMI. I have often ended up using oal's that fall slightly outside of SAAMI spec., and am drawn toward using the longest oal that will reliably function in my firearms.

Bench test is pushing the nose of a cartridge against your bench or table top, if the oal doesn't change, your golden.

Pull test is the same basic concept, try to pull a bullet out of the case using your fingers, twisting and pulling with all you've got. If it moves at all you need to seat deeper, as you don't have enough bullet shank inside the case body.

GS