New 147 grain BBI + N320

[MissionaryMike]

Looks like I'm having to develop a new load if I want to continue to shoot my favorite coated, lead bullet brand - BBI. I've determined that the new OAL will have to be 1.08-1.085" in my CZ. I have a whole bunch of VV N320 to use up. For those of you loading out to 1.08-09", how much powder are you using to get 130ish PF?

Thanks,

MM

[rev1911]

That's pretty short for a 147gr. What is the length of those bullets?

[MissionaryMike]

So I measured the lengths of ten "old" style 147 FP bullets, which averaged 0.6671". Ten "new" style averaged 0.6448". That's 0.0223" shorter. The difference in OAL w/ the old and new is 0.035" (1.12-1.085). Therefore, the new bullets are being seated only about 0.0127" deeper than the old ones. That's probably not enough to cause concerns about pressure spikes or anything, right?

[Smitty79]

You should push test the no lube groove 147s again. I can load an Acme bullet, that looks like your Black Bullet, to 1.14 in my Shadow.

[GJGary]

Acme 147gr and the new 147gr bbi are different, the bbi oal is much shorter.

All my CZ barrels are reamed. So the mag is the limiting factor but every new bullet gets the drop test.

[optimator]

In my Apex barrel the 147 BBI can only be loaded to 1.135. The Acme's plunk and spin at 1.15.

[MissionaryMike]

Acme 147gr and the new 147gr bbi are different, the bbi oal is much shorter.

All my CZ barrels are reamed. So the mag is the limiting factor but every new bullet gets the drop test.

I'm fairly confident that this new, shorter OAL can work. But just in case I don't like it, who reamed your barrels?

In my Apex barrel the 147 BBI can only be loaded to 1.135. The Acme's plunk and spin at 1.15.

You talking about the 147 BBI w/ or w/out the lube groove?

[Terry44]

In my Apex barrel the 147 BBI can only be loaded to 1.135. The Acme's plunk and spin at 1.15.

I'm about to start developing a load for this as well. Is anyone else using this new BBI 147 w/out the lube groove? What OAL are you using?

[GJGary]

Acme 147gr and the new 147gr bbi are different, the bbi oal is much shorter.

All my CZ barrels are reamed. So the mag is the limiting factor but every new bullet gets the drop test.

I'm fairly confident that this new, shorter OAL can work. But just in case I don't like it, who reamed your barrels?

In my Apex barrel the 147 BBI can only be loaded to 1.135. The Acme's plunk and spin at 1.15.

You talking about the 147 BBI w/ or w/out the lube groove?

I had a great member of this forum send me one to borrow and I did 4 cz 9mms. I sent the reamer back with a little thank you.

I have reamed every cz I own and don't regret anything. Whisk I would have done it sooner.

[MissionaryMike]

Do you remember which brand/model the reamer was?

[MeatPuppet]

It was a 9MM Manson Throat Reamer and GJGary was great! I dont know what the Model is.

[MissionaryMike]

So I got out to the range and shot two loads through the chrono. Both were 1.08", one w/ 3.2 grains of n320, the other w/ 3.1.

A.) 3.2 grains averaged just over 908 fps, which yields a PF of 133.5.

B.). 3.1 grains averaged about 882 fps, or roughly 129-130 PF.

Chandler told me that accuracy w/ the 147 really stands out when you get to the 900 fps zone, but I can't confirm that from today's chrono session. I didn't have a solid rest. But I'll take his word for it. I guess that means my new load will be the 3.2 grains. I doubt I would notice a difference in the recoil impulse between a few PF when under the duress of the clock and course.