Help with .356 9mm barrel, bullet choice

[Guitarmageddon]

Hello all, long time lurker, first time poster. Since I have started reloading, this forum has inevitably been a top search result for almost every question I have. Now to my lengthy question...
 

Im in kind of a pickle revolving around proper coated 9mm bullet size for my CZ. A few weeks ago, after developing numerous loads and relatively being new to reloading 9mm, I decided to have a close look inside the bore of my cz p07. Lots of lead throughout! Over several days I experimented with wipeout, mpro7, hoppes  #9, clp, shooters choice lead remover, and a Lewis lead remover mechanical de-leading rod/bronze patch setup. I’ve pretty much gotten most of it out at this point but man it was stubborn. But the thought had not occurred to me before all this that hey, maybe you have got a large bore diameter for what you are shooting! Duh….
 

So I slugged the bore today with a kit from Meister bullets that I got on eBay. Quite a simple process actually. I had a hunch this barrel would be large, and it indeed was; it measured out at .356. So this definitely explains some leading. During my load development, I toyed with various blue bullets which actually measure at .355 (not sure why they do this, presumably to avoid coating shaving), and summit city bullets in .356. I can’t say definitively if I had issues caused by the .356 sized bullets but having a .356 bore that is entirely possible.
 

As I do some research, I see this is quite an odd size to have. I can’t use .356 bullets presumably because they are the same size as my bore. So if I go with a bullet the same size, then I would be wanting a FMJ in .356. Do they make those commonly? I saw some marketed as 38 super, (.356 fmj) but all out of stock of course.
 

Then I consider another option. I have a boatload of 125gr blue bullets in .358 for 357/38spl…would this be too big of a jump and cause other issues in a .356 bore? I experimented with a couple .357 coated rainier bullets a buddy had on hand earlier. And even at .357, while they did seat just fine on his standard Dillon 9mm toolhead/dies, I could see that the chamber was getting a little crowded. They plunked, but barely so…I have the feeling id have to seat a fatter bullet SUPER deep. Like..sub 1.060 deep. The tester at .357 was right around that.

I am going to thoroughly clean the bore and test out the remaining .356 coated bullets and determine how bad (hopefully they don’t) leading is. Anyone have any thoughts or suggestions on this? Thanks!

[Ben53]

First, make sure you get all the lead out of the bore.  Once leading starts, it grows fast.  Next, if you have a .356" bore then you should be good with same size bullets, although it's common practice to shoot .001 or .002" oversized in many handguns.  With lead, that won't hurt a thing, and you can consider any "coated" bullet, like Blue Bullets, to load the same as plain lead.  Jacketed is a different story, and you'd want to stick with .356 if at all possible.  I'm not sure about jacketed, but there are a number of companies making coated bullets that will size them to .356.  

[Guitarmageddon]

Thanks. So I found some zero .356 fmj aka 38 supers to try. I thought that 38 supers were .355 but I guess I was wrong. Never a caliber I had a need to search for before. Aside from that, I see the hornady action pistol HAP at .356 but damn they are pricey. If prices come down I may snag a few to play with. 

 

So for jacketed I will stick with .356 in this .356 barrel and should be ok right? And for plated/coated/cast, .357 is the answer. Except that's kind of a weird size to find isn't it. They are typically .358. Downside of going to .358 if I use my 38/357 blue bullets i have is that I suspect Ill run into some problems chambering or have to seat so deep its not practical, due to the profile of the tip, and meeting the rifling, etc. 

[superdude]

I'm not sure you need to match the barrel's .356 with jacketed bullets. Barrel specs for 38 Super (and 9mm and 38/357 revolvers) are a groove size of .355 to .359. Undersized jacketed bullets shoot very well through them. For example, I've Ransom Rested 9mm handloads through a Ruger Blackhawk revolver with a conversion cylinder and a .3577" groove diameter barrel and produced very small groups with .355 jacketed bullets, including 24 shots in 1.40" at 25 yards. Other .355 bullets were as accurate as, or better than, .357 bullets. If matching the barrel dimensions is required by jacketed bullets, my data does not agree with that. 

 

Lead bullets might be a different story and undersize lead might contribute to leading. I've not tested that so I can't say.

[Guitarmageddon]

7 hours ago, superdude said:

I'm not sure you need to match the barrel's .356 with jacketed bullets. Barrel specs for 38 Super (and 9mm and 38/357 revolvers) are a groove size of .355 to .359. Undersized jacketed bullets shoot very well through them. For example, I've Ransom Rested 9mm handloads through a Ruger Blackhawk revolver with a conversion cylinder and a .3577" groove diameter barrel and produced very small groups with .355 jacketed bullets, including 24 shots in 1.40" at 25 yards. Other .355 bullets were as accurate as, or better than, .357 bullets. If matching the barrel dimensions is required by jacketed bullets, my data does not agree with that. 

 

Lead bullets might be a different story and undersize lead might contribute to leading. I've not tested that so I can't say.

 

Ok thanks. I never noticed issues with leading until switching from FMJ to reloads, specifically coated. First round of tests were with blues, which Im almost certain caused the majority of it. Now that the leading is all scraped out. Im going to test again with .356 coated and inspect. Otherwise, I will get a pile of .355 or .356 FMJs and go from there. 

 

I found some .356 hornady HAP to test, as well as some ZERO .356 fmj to play with too today

Edited July 13, 2021 by Guitarmageddon

[Guitarmageddon]

Something else I've observed. The hodgdon site lists an extremely short OAL and very conservative powder estimate for those bullets. I've seen a plethora of posts on this forum speculating as to why that is. But if I am shooting these in a .356 barrel would some of that pressure be mitigated? GRT (Gordons reloading tool) has this exact projectile in their database and it simulates I could likely go a bit higher. I intend on loading them a little longer and with a little more powder than the 3.3gr of hp38 the load data recommends, at 1.069 oal.

[HOGRIDER]

21 minutes ago, Guitarmageddon said:

Something else I've observed. The hodgdon site lists an extremely short OAL and very conservative powder estimate for those bullets. I've seen a plethora of posts on this forum speculating as to why that is. But if I am shooting these in a .356 barrel would some of that pressure be mitigated? GRT (Gordons reloading tool) has this exact projectile in their database and it simulates I could likely go a bit higher. I intend on loading them a little longer and with a little more powder than the 3.3gr of hp38 the load data recommends, at 1.069 oal.

Recently purchased my first CZ........a Shadow2 Orange..........and setting up reloads for this particular pistol/barrel was a huge CHALLENGE!  I received a lot of great info from this Forum and from here:

https://czfirearms.us/index.php?topic=100352.0

 

I think everyone will agree that the CZs have a short, precise chamber that will cause us to rethink our reloading habits!  Of course, it's a European pistol and their specs are somewhat different.

 

In my research, the first thing I needed to determine was the preferred COAL for the bullets I was going to use/start with!  This post will definitely help with that process:

 

https://czfirearms.us/index.php?topic=103620.0

 

As an example, Blue Bullets sent me some samples of their two 147g coated lead offerings.  When determining the MAX COAL for their "new" round nose offering, it averaged out to 1.125".  For their standard 147g coated flat point profile, it averaged 1.136" as MAX.  

 

I would highly recommend starting out with some FMJ or JHP bullets!  And definitely determine the COAL that your barrel likes/prefers!  

 

HTHs!

 

[Guitarmageddon]

Definitely agree. And when it came to basically every coated offering I was having to seat at around 1.070-1.090. I could get away with 1.095 for 147 gr coated stuff but not much longer. There were some longer nosed FMJ profiles that can seat to quite a bit longer OAL however. Hoping some of the .356 options I've ordered this week can accommodate. It's a total pain to have to go to such a great seating depth.

[superdude]

As noted, you'll have to determine the OAL required for each bullet you use. This figure shows the 'just fits' OAL for several different bullet designs in a CZ barrel;

 

[EarlKeese]

I've had similar issues loading coated lead projectiles for my CZ's. Slugged all of my barrels and sure enough, all but one of my CZ's are .356. I load .357 diameter 135's and no longer have lead fouling or accuracy issues.

[Guitarmageddon]

1 hour ago, EarlKeese said:

I've had similar issues loading coated lead projectiles for my CZ's. Slugged all of my barrels and sure enough, all but one of my CZ's are .356. I load .357 diameter 135's and no longer have lead fouling or accuracy issues.

What .357 do you choose? i have some blue bullets .358 but im wondering if those will be a hell of a time plunking. 125gr i use in my 38/357