So I slugged my barrel and need recommendation

[DaveO]

Just slugged my 9mm pistol and it measured .356 with my micrometer.
What do I size my boolits to?
Do I go .001 over the measured size (.357) or use the .356 sizer?
They will be powder coated.
I am new to casting, but have been reloading for years.
Thanks

[Rcmaveric]

Just slugs the throat a little to get an impression of it.

You can size from throat diameter to bore diameter. Take your pick. I like to be about throat diameter.

Sent from my SM-G965U using Tapatalk

[dtknowles]

Will rounds loaded with .357 bullets fully chamber and easily extract if not fired? If you use standard dies in the normal manner your ammo might look bulged by the bullet and if your bullets are soft the may get sized down during seating. This is more of an issue with heavier bullets. You can back off the sizer some and use a bigger expander if your chamber is typical but you need to verify reliable function. Sloppy fit let's the gun run freer but not necessarily as accurately. If your lands are not a lot narrower than the grooves and you are using soft bullets even .355 bullets should be fine. Not knowing all your specifics I would suggest .356.

Added. It might not be an issue for you but if you want to use the ammo in more than one gun, you have to accommodate the smallest chamber and the fussiest gun. I have four 9 x 19's and one is very fussy.

Tim

[tazman]

Start with .357 and see if they chamber freely. I own 8 different 9mm handguns and they all accept .357 boolits with no issues and shoot accurately with them.

[dale2242]

I sized my bullets for my 9MM to .358.
They chamber and shoot just fine...dale

[onelight]

I would start with components that match the load data you have if they show .356 try them , see if they perform like you need. Be sure to use enough flare so you don't scrape off the powder coat , crimping separate from seating also helps protect the coating . I would start with factory dies and expanders.
If you get leading the the knowledge and experience these guys have will help find a solution.

[PJEagle]

When I acquired my first 9MM I slugged the barrel and came up with .356. I experimented with both .356 and .357 powder coated bullets. The .357 bullets reduced the group size by about 30% compared to .356, so I continue to use .357 in that pistol and the other two 9MM I have acquired since that time. I had to switch to a 38AP sizer button in my 9MM Lyman M die. All of the other dies are standard Redding 9MM.

If you have any trouble with the .357's pluking, I would advise contacting DougGuy and arranging for him to "throat" your barrel.

[Petander]

This is such a good read:


http://castboolits.gunloads.com/showthread.php?121737-Setting-up-for-boolits-in-a-new-9mm

[Phlier]

This is such a good read:


http://castboolits.gunloads.com/showthread.php?121737-Setting-up-for-boolits-in-a-new-9mm

+1 to reading that thread.

As you are going to be PC'ing, I highly recommend you get a boolit design meant specifically for PC'd boolits. Something like this (https://www.mp-molds.com/product/357-359-125-flat-round-nose-flat-base-8-cavity-aluminum-no-lube-groove-mold/). That's not to say that you can't get other designs to work well, you can. A lot of guys shoot a variety of different boolit designs, PC them, and shoot them successfully. But IMO, the design of that boolit will make the learning curve much easier to get through.

[higgins]

You're fortunate to have a 9x19 that should do well with "normal" size 9mm bullets. European 9s are routinely about .358 groove diameter. I had a Beretta that slugged .358; I contacted Beretta to see if that was oversize and they responded that their maximum groove spec. is 9.1mm (.3582). Being able to load smaller bullets should also save you the aggravation of searching for thinner 9mm brass to load .358-.359 bullets without them being sized down during loading.

BTW, I found that Blazer Brass and current production Federal seemed a bit thinner than most other brass.

[Tom W.]

Yep,one of my molds will cast boolits that .358 sized would shoot in my Ruger and the Glocks that I had, but will barely chamber in my CZ. For that boolit I had to size to .357 to fire reliably in the CZ. Another mold that I have will chamber in the Ruger and the CZ sized to .358


I dunno why.....

[DaveO]

Thanks for all the replies, lots to sort through now
Read the linked page and will follow his suggestions.