Overcharged 9mm with 5.5 grains of VV N-340. Bad, right?

[IMtheNRA]

Well, while experimenting with my press in order to iron out some COAL issues, I got distracted by my "experiments" and overcharged a small batch of 9mm rounds with 5.5 grains of VV N-340.

I'm using Winchester 115-gr FMJ FB bullets, COAL=1.135

The Laupa and Vihtavuori reloading guides list the following data for the Lapua bullet of this weight and type. I have no reason to believe that the Winchester bullet would require more powder than the Lapua bullet.

N340 0,31 4.8 344 1129 0,35 5.4 372 1220

That's 5.4 grains max load...

I should NOT use these rounds, right?

 

[The-Fly]

.1 gr over? Nothing to worry about. Most of the time load data is pretty conservative, and a tiny extra powder isn't going to hurt.

But be safe.....fire a couple of em off, check the brass for ANY signs of over pressure. If they come up ok (which I bet they will), then your good to go.

 

[Idano]

IMtheNRA,

Since you said you loaded 115gr Winchester FMJ I would say you're okay; they will be warm loads. Here is what the Vihtavuori site has listed:

VN340
115gr Hornady HP-XTP 5.2-5.9 grs
115gr Lapua FMJ-RN 4.8-5.4 grs
115gr Rainier RN 5.0-5.4 grs​

If you're loading these on a single stage press probably never going to be an issue, but if you load on a progressive I would recommend looking for a powder that is more forgiving. Most reloaders who get into trouble usually use a very hot powder with low case capacity so if anything goes awry and they dump a grain off or a double load then they have a problem. For progressive loading l like to find a load where a .5 gr variance won't be an issue and case capacity is above 50%.
I use 5.8 grs of Unique for 115 gr, it definitely fills the case.