wally720

The volume displacement with water is interesting. Hadn't thought of it like that. Hope I didn't come off sounding like a jerk, TonyK. I've been accused of over thinking things.. Lol.. So be it. I don't think it's good to blindly follow the manuals and not have an understanding of how things work. Even more so when you start adjusting COLs to fit your gun. I'd hate to see someone make a mistake either from carelessness or lack of knowledge.

Specific gravity is irrelevant. http://www.nosler.com/9mm-luger-parabellum lists the actual EMPTY case volume in gr of water. They do also list load density of the powder, in percent volume of the case after the bullet has been seated, for each powder type and charge they have tested. Some of those powders don't fill the case and some are compressed. It was interesting to read that. You can look up the dimensions of different bullets and do the math, but if you seat a 115 and 124 gr bullet to the same COL (as an example: both RNs from same manufacturer), there is a .047 cubic inch change in case volume. Obviously using the same powder charge will increase or decrease pressure in the case. The same would apply to a RN vs. FN bullet of the same grain size. If the lengths are different, which they most likely are, seating them to the same COL will result in different pressures if the same powder charge is used because case volume, after the bullets are seated, will be different. So, the issue becomes: if you seated FN and RN the same COL, you may have a pressure problem. And if you aren't taking the different length of the bullets into account when setting you seating die, maybe your just lucky that something bad didn't happen. And I think that's why I originally started this thread. It's been a while and I can't remember.. lol.. My decision was to load all the FNs for my Glock and buy RNs to load for my XDm, as it just seems not to like any recipe I've used for it with a FN

That's exactly the problem I had with Xtreme FNs. Data says COL should be one thing. They hit the rifling in my XDm so I shortened them to 1.084 after also decreasing powder charge some. Accuracy, for whatever reason, just wasn't acceptable to me. I ended up loading them all with 4.0 titegroup and shoot them through my glock, which loves them. Gone back to round nose for the XDm and trying 124 gr plated from Rocky mountain reloading. They are loaded to jacketed velocity.

Final results: 4.0 gr titegroup gave fantastic grouping in my G26. After trying two other powders, it seems the XDm just doesn't like this bullet much. Going back to round nosed.

Yes, exactly, Mstang. It takes dropping the col below 1.085 in my XDm to get the cartridge to freely turn in the chamber.

And its hard to tell if your post uploads on this phone, so sorry for redundancy

They are actually conical nosed bullets. I tested a few different lengths with the drop and spin test in my two 9mm barrels and pretty much settled on 1.080. I'll make up several powder charges and hopefully test tomorrow.

Actually I set up my press today and tested a couple different lengths in my two 9mm barrels (no powder or primer) doing the drop and spin test, and in think I'm settling on 1.080-1.083. The bullets are conical nosed. I'll make 4 or 5 test powder charges and test them hopefully tomorrow.

Thanks for the advice, guys. I've run across some data and found some pretty short oals, so with that and what y'all have posted, I've got a good idea where to go from here.

Lol... ok, flat nose. Points are not flat or they wouldn't be pointed I just found another post similar to mine, so, yeah, I figure I'll keep same case volume by shortening oal and try some out.

I switched from 124 gr plated round points (X-treme) to 124 gr flat points, due to availability / sale price. The flat points are considerably shorter, .059", so by keeping the oal the same, it will create more case volume. More case volume equals less pressure and possible squib or cycling problems. By shortening oal to keep the same case volume and pressure, I'm making the oal pretty short and have some concerns with possible feeding issues. Hogdon has no load data for flat points. Any suggestions on where to start? Just start over with new test loads, keeping same oal with more powder? (currently using 4.2 gr titegroup with rn)