First cast bullets test shots

[KYregular]

So I loaded up my first cast and powder coated bullets and ran them over a chrono today.

CZ P09
124 grain round nose flat points
BE86 powder 4.6, 4.8, 5.0 grains
OAL 1.10
Sized at .356 and .357
4.6 1050 fps SD 15 .356 sized
4.8 1104 fps SD 7. 356 sized
5.0 1138 fps SD 8 .356 sized (great group)

Didn't try many .357



My issue is that:
1) .356 had trouble going into battery. 357 was worse. Though all passed initial plunk test, when I took the dirty barrel and tried, they would not. Had "blue" build up on the lands. Ran a brush thru and they plunked fine. In the pic you will see a build up around the case mouth. Could I have had too much powder on them when I baked them? Should I try extra taper crimp? Should I try sizing down to .355 (which my barrel slugged at?) Cannot find a Lee .355 sizer anywhere. All input appreciated.

 

[WestKentucky]

You want slightly oversized so .356 or .357 is right. Perhaps a bit much on powder but they look nice. Did you size before or after powder coating?

 

[KYregular]

You want slightly oversized so .356 or .357 is right. Perhaps a bit much on powder but they look nice. Did you size before or after powder coating?

Powder coated then sized. Good point, could try it twice. I think .357 is gonna be too tight for a CZ, they have notoriously tight chamber tolerances.

 

[brewer12345]

Maybe try a different bullet shape, like a truncated cone.

 

[KYregular]

Maybe try a different bullet shape, like a truncated cone.

Don't think it's bullet shape as much as build up from the PC. When I first experimented on OAL they were plunking fine 40 thou longer.

 

[243winxb]

Try a shorter COL. More case mouth flare/bell.

 

[KYregular]

Maybe I need to expand the case mouth a little. Just remembered they were pretty tight.

 

[KYregular]

Just loaded a couple dummy rounds with the mouth expanded more and they came out much cleaner. Notice the bullet on the left has a slight lip that I am loading out to.

 

[WestKentucky]

First thing to do is size after coat. Your .356 grows to .357 or .358 with powder. A true .356 will likely function.

edit... I r dumb. I read the words and fluffed them around in my head.

 

[garandsrus]

A couple things:

1) .356 or .357 is what you want.

2) Can you post a picture of the bullet after seating but before chambering? You want to belle (flair) the case mouth prior to seating cast so you don’t scrape the side of the bullet. Yours almost look like the coating was scraped off during bullet seating. This would be due to insufficient belling of the case mouth.

3) You shouldn’t have any of the blue buildup anywhere!

4). You might need to seat a few thousandths deeper, but if they plunk ok, they should be fine, as long as they feed ok.

5). You should only need to size once, after coating. If you are sizing a lot, more than .005 or .006, you probably want to size in two steps. One could be before coating and one after.

6). If these were the same bullets from a previous thread, the coating looked too thick which may be part of the problem.

7) it should be hard to scrape the coating off. If it isn’t, you didn’t bake them long enough or at a high enough temp.

Hey! You posted a picture I asked for before you knew I asked for it but while I was typing.

 

[garandsrus]

This is the Mihec 122 gr 8 cavity mold, right? I use the same one. Those look good!

 

[KYregular]

This is the Mihec 122 gr 8 cavity mold, right? I use the same one.

Yes sir

 

[KYregular]

A couple things:

1) .356 or .357 is what you want.

2) Can you post a picture of the bullet after seating but before chambering? You want to belle (flair) the case mouth prior to seating cast so you don’t scrape the side of the bullet. Yours almost look like the coating was scraped off during bullet seating. This would be due to insufficient belling of the case mouth.

3) You shouldn’t have any of the blue buildup anywhere!

4). You might need to seat a few thousandths deeper, but if they plunk ok, they should be fine, as long as they feed ok.

5). You should only need to size once, after coating. If you are sizing a lot, more than .005 or .006, you probably want to size in two steps. One could be before coating and one after.

6). If these were the same bullets from a previous thread, the coating looked too thick which may be part of the problem.

7) it should be hard to scrape the coating off. If it isn’t, you didn’t bake them long enough or at a high enough temp.

Hey! You posted a picture I asked for before you knew I asked for it but while I was typing.

Yeah the dummy rounds look much better since I increased the bell. The first 10 or 12 cartridges shot flawlessly, after that the build up was just too much I believe.

 

[GoldieMI]

Powder coated then sized. Good point, could try it twice. I think .357 is gonna be too tight for a CZ, they have notoriously tight chamber tolerances.

CZ are notoriously tight and short leades..flare a touch more before seating, maybe seat a touch deeper.
Did the baked PC'ed bullets pass the smash test?

 

[KYregular]

CZ are notoriously tight and short leades..flare a touch more before seating, maybe seat a touch deeper.
Did the baked PC'ed bullets pass the smash test?

Yes on the smash test. When I was initially testing oal they plunked fine .040 longer, I was just trying to get that bullet flush with the lip. Yes on the CZ leades, I've always believed that has always contributed to their accuracy though.

 

[GoldieMI]

Without going to the shed, my CZs are like 1.08" with 124 TCs if I remember correctly. They are much shorter than the rest of the 9mm brands for me.
they get their own color on bullets though so I don't waste the shorter ones in less picky pistols

 

[bersaguy]

My SP-01 was not a huge fan of the Lee 124g flat points I ran thru it. Had to seat very short to plunk, still have some more testing to do with the round nose, which should do better, but they sure are a very round....round. they also need to sit fairly short. Looks like you're on the right track