Problems with 9mm loads using FMJ's

[Primer]

A couple of weeks ago I was doing some loads for my 9mm LR and found a nice load using 3.4gr of Vihtavuori N320 using 124g GM Hardcast round nose bullets but decided to also try loads for a couple of types of copper jacket bullets and have run into problems as follows:

1st type is 124gr round nose (unknown make) brought a bag from my club and on inspection they are virtually identical to the Magtech factory's and mic out dead on 9mm, copper jacket and exposed lead core at bottom.
I did 3 different loads from the Vihtavuori manual using N320
3.4gr expected fps 951 actual average over 10rds 641fps
3.7gr expected fps not known but actual average over 10rds 806fps
4.0gr expected fps 1070 actual average over 10rds 851fps

2nd type is 123gr round nose and these mic out to 9.03mm, full copper no exposed lead core
I did 2 loads for these as above
3.4gr expected fps 951 actual on first round 465fps, 2nd round only made it 10" down the barrel and had to be tapped out using a cleaning rod and hammer, I did not use any more of the rounds and on returning home I pulled the rounds and checked powder weights and these were all 3.4gr/3.7gr as loaded.

1. so what can the problem be, why am I not getting close to the expected fps on the jacketed loads as my lead load is only around 50fps short of the expected? i'm not sure on the expected fps of the Magtech factory loads but i'm getting around 1200fps, I pulled a round and it seems to be a compressed powder load (unknown powder)

2. can 0.03mm make all the difference on the 2nd fmj bullet to make it too tight for the bore and thus resulting in more backpressure and forcing the bolt back too early?

3. My LR is an older uzi version but running the lead load through a brand new glock version shows around a 60fps difference between the guns but I have the gun booked in for a service anyway to get the buffer tube spring changed in case its worn out and not holding the bolt in place long enough to force the bullet out the barrel (and everything checked out).

Any help/suggestions greatfully received, luckily I was recording each shot through the chrono and also heard the difference in report and didn't fire a follow up shot down the blocked barrel.

[majordisorder]

I use both lead and plated loads in .45ACP. From memory my lead loads are around 4g of AA#2 and plated around 7g to achieve the same velocity. So you don't have a problem other than you're not using enough powder. I don't know the technical reason why plated requires so much more powder (friction I guess) but if you read up online about the differences you'll see this is a common observation.

[Primer]

I use both lead and plated loads in .45ACP. From memory my lead loads are around 4g of AA#2 and plated around 7g to achieve the same velocity. So you don't have a problem other than you're not using enough powder. I don't know the technical reason why plated requires so much more powder (friction I guess) but if you read up online about the differences you'll see this is a common observation.

So do I need to look at changing to a different powder as 4 grains is shown as max load in the vihtavuori manual, although the Lee manual shows 4.4 is max? I also have 3n37, bullseye and Red Dot at my disposal.

[toffe wrapper]

primer
Sounds like you have 1 bullet that is harder than the other so will need more powder.
If you have a lee factory crimp die load a dummy round of each with a heavy crimp you may see 1 is deformed the other does not have much of a mark.
When I tried plated in 9mm they needed less crimp but my Glock version did not like them it also did not like lead so now use TMJ S&B for reloads.
no matter how hard the crimp they do not deform or mark.

TW

[Chapuis]

Don't you mean a taper crimp die rather than a factory crimp die toffe wrapper? I don't think Lee make factory crimp dies for 9x19mm but I may be wrong.

[dromia]

They do make a factory crimp die for that calibre.

[Chapuis]

I wasn't sure Dromia, but still wouldn't a taper die be the better option?

[dromia]

As he is suggesting using the crimp die to check the relative hardnesses of the bullets then indeed the factory crimp die would be best.

[Chapuis]

Surely its not really possible to properly test the relative hardness of a bullet using a factory crimp die?

Primer you are aware that load data for jacketed and lead bullets is totally different for the same weight of bullet?
What reloading manual using and getting your load data from?

I have to admit that when I reloaded 9mm for pistol I found it a bit of a pain compared to .45acp or any of the straight walled revolver cartridges that I loaded for. I did find that a taper crimp die was a great investment and an absolute positive help as regards feeding.

[Primer]

primer
Sounds like you have 1 bullet that is harder than the other so will need more powder.
If you have a lee factory crimp die load a dummy round of each with a heavy crimp you may see 1 is deformed the other does not have much of a mark.
When I tried plated in 9mm they needed less crimp but my Glock version did not like them it also did not like lead so now use TMJ S&B for reloads.
no matter how hard the crimp they do not deform or mark.

TW

Ok I've done a crimp test and the fully encased bullet (the one that was really low on power and got stuck in the barrel) actually appears softer than the other with the lead core exposed as there is definitely more defined crimp mark, they are closeish on mic ing them up the fully encased was 8.94mm and the other 8.96mm.

What I would say is on pulling the bullets the fully encased one popped out with one hit of the puller and the other took 3 or 4 hits, I replicated this several times and had the same result, so I'm guessing the looser one will have a bearing on lower pressures being achieved in the case.