Taper crimp - is this right

[toffe wrapper]

physeptone

The way 9mm headspaces is old tech and safe. 45 ACP headspaces the same and the good old tommy gun has a lot of metal hammering out the rounds.
Bolt on the 9MMLRR is about the same size as the 9mm SMG that was able to go full auto. That is why you only straighten the case back so you can still feel the rim.
DM is doing it the correct way making up test dummy rounds and getting used to loading rimless pistol rounds. Once he has a few drill rounds he can work them through the action and check for function and ensure the heads are not pushed in on chambering or pulled out on ejection.
Then add powder to produce a batch of test loads chrony test loads. Pick the one that groups best closest to best fps /power factor required to ensure rifle cycles then thats it load developement done.
No jamming in the lands, setting back from lands neck turning, trimming or which primer just crank them out and shot them.

TW

[phaedra1106]

My 9mm with a solid crimp measure as follows,

Case diameter at base (above extraction groove) 9.82mm

Bullet diameter (immediately above rim) 8.99mm

Case diameter at rim after crimp 9.51mm

= crimp area of .26mm width


PRVI Factory measure as follows,

Case diameter at base (above extraction groove) 9.80mm

Bullet diameter (immediately above rim) 8.98mm

Case diameter at rim after crimp 9.50mm

= crimp area of .26mm width

Both have identical amounts of case to seat off.

[Dangermouse]

After sorting out my .308 brass from the weekend, I made a cup of tea and set up the 9mm dies once more.
I hope that the brass that I accumulated is not typical of "qulity2 brass. The flash holes are all over the place & different diameters. I did not bother weighing the cases or checking volume. Despite having the best part of 400 once fired cases I think I will splash out on some new and see if they are better constructed.

I did put 10 dummy rounds together and cycled them through my gun 10 times. My arms are hurting now from all that pulling! I did not get one miss feed, which I was getting the last time I tried cycling purpose made snap cap/dummy rounds.
Measuring the rounds after all that and I did not find that any had shortened, so I am happy that they are up to the task of being magazine fed safely.

Have realised that my funnel and bullet trays will not let me pour powder in to the small 9mm cases, so will need to sort that out before I go at this for real. I think I have everything else so just waiting for pay day and perhaps a trip up to reloading solutions,

Thanks for all your help,

DM

PS found my A-Z of reloading (Edition 8) this morning and sat down with a cup of tea to read the section on pistol cases. I don't wish to sound arrogant but I found the information to be no better than that in the Redding info sheet that came with the dies, I certainly did not learn anything,

DM

[phaedra1106]

Great stuff DM :)

Best pistol cases are Starline, Midway UK did have the +p version in stock but they are out again. If you are in the US at any time Starline sell direct, $67 for 500 cases.

If you want a sample let me know and I'll put 10 cases in the post for you.