45acp bullet change & chambering issues

[Col. Plink]

Hey y'all,
I recently changed bullet types to hardball with all other parts of the process staying the same (except for a minor decrease in powder). My normally boringly-reliable CZ-97 will not fully chamber them. About 1/8" remains for the slide to close and is very hard to rack and release it.

By comparison, the same setup runs like a top with fmj's.
No change but the bullet type, which is puzzling for causing jams with the slide so close to being shut. Bullets are Precision 230gr RNF. I've heard of SWC's causing grief but don't use them.

Thoughts on what's happening? Thanks in advance!

 

[Tony k]

What is your oal? My first guess would be that your bullet is hitting the rifling.

 

[243winxb]

Seat bullet deeper, shorter OAL. Bullet diameter right in front of case mouth should measure .450" Check the taper crimp first, may need a tiny bit more.

 

[Okcafe86]

Do they pass the plunk test?

 

[Walkalong]

http://www.thehighroad.org/showthread.php?t=506678

 

[Col. Plink]

It appears the oracles at THR are right again! Here's the photographic evidence.

I looked at the bullet contour when I compared to the commercial fmj I use for judging bullet depth, but clearly not close enough! What OAL should I look for outta this one?

 

[Okcafe86]

If you have Lyman's bullet casting handbook it's got some good data you can use for that.
I don't know much about the metric system but I seat my lrn to 1.270"

 

[Walkalong]

I seat various .45 ACP 230 gr RN bullets @ 1.260 to 1.265.

That bullet actually flattens out a bit at the tip, so I would start shorter, perhaps 1.250 to 1.255, maybe even shorter.

The CZ 97 is a superb .45. My younger son lusts for mine.

 

[Toprudder]

I have Xtreme 230gn RN that I can seat to 1.275 OAL, but the RMR 230 thick plated I can't seat over 1.215 before it hits the rifling.

Find your max OAL by using the "plunk" test (or push test) then seat about 0.015 shorter than that.

 

[guncheese]

use the plunk test to determine your OAL
thats the only way to be right
seat till it plunks properly and then .01-.02" more and it will be fine

 

[LivewireBlanco]

+1 for the plunk test.

 

[Cheetos]

It appears the oracles at THR are right again! Here's the photographic evidence.

I looked at the bullet contour when I compared to the commercial fmj I use for judging bullet depth, but clearly not close enough! What OAL should I look for outta this one?

That bullet looks a lot like MBC 200gn RNFP. I have to seat those down to 1.20 for them to pass the plunk test in my Sig. I normally seat RN to 1.265.