Exact fit in bore...how to handle?

[Martin Luber]

Ok, in a fit of inattention, l sized my whole batch of 9mm to 0.355 and I have a 355 groove. I thought I had a 356 sizer installed. They are smokey and don't shoot as well as expected. I'm not scrapping them yet. Would they work better with more powder or less? A harder spank might slug them up? What is your experience here? I haven't checked if they are leading but he excess smoke is a clue. BHN is 11

Thanks

[Dusty Bannister]

It would be helpful to know the type of lube you are using, or if you just powder coated them.

[mehavey]

sized my whole batch of 9mm to 0.355 and I have a 355 groove.Ditto question above.
Are they PC'd (yet)?

[sigep1764]

How hard is the lead?

[littlejack]

Powder coat would make'm fit more better. If you powder coat? :guntootsmiley:

[reddog81]

If they aren’t leading I wouldn’t worry about it. It takes less time to check for leading than it does to type this post.

[centershot]

If they aren’t leading I wouldn’t worry about it. It takes less time to check for leading than it does to type this post.

^^^ This, and if they meet your accuracy parameters, all is good. The general recommendation for bore diameter plus .002" is sound advice. If you have headroom in your loading data a little heavier powder charge may obturate a bit more.

[mdi]

I'd think a 9mm charge (to 35k psi) would bump up a BHN 11 bullet enough to give a tighter fit...

[fredj338]

^^^ This, and if they meet your accuracy parameters, all is good. The general recommendation for bore diameter plus .002" is sound advice. If you have headroom in your loading data a little heavier powder charge may obturate a bit more.
I think + 0.001” is pretty much a std with cast but obviously every bbl is diff. I do fine across multiple calibers in multiple guns sizing that way.
Yes powder coating would bump those up but if already lubed & sized, i would toss them back in the pit & start over if accuracy isn't there.

[mehavey]

The general recommendation for bore diameter plus .002" ....Perchance did the poster mean groove diameter?

[Rickf1985]

9mm is .356 and cast boolits should be at least .357 so if he is at .355 he is away undersize no matter how you look at it. I don't think extra powder is the answer to that much gap. I am thinking that boolit might just fall through the barrel if dropped in.

[centershot]

Perchance did the poster mean groove diameter?

Oops! Yes, groove diameter.

[fredj338]

9mm is .356 and cast boolits should be at least .357 so if he is at .355 he is away undersize no matter how you look at it. I don't think extra powder is the answer to that much gap. I am thinking that boolit might just fall through the barrel if dropped in.

Maybe. 9mm is 0.355". I have run 0.356" in all my 9mm just fine. I settled on 0.357" though as belt & suspenders. If I get another 9mm, I dont want to be bothered with diff loads.

[GONRA]

GONRA hasa pyle of foriegn auto pistols over the decades.
Some have really shallow rifling grooves! !!
(Wear 'n tear? Design? ??)
Harder boolit alloy does the trick! !!

[fredj338]

GONRA hasa pyle of foriegn auto pistols over the decades.
Some have really shallow rifling grooves! !!
(Wear 'n tear? Design? ??)
Harder boolit alloy does the trick! !!

No just older barrels were designed for jacketed only. Few shot lead bullets thru 9mm in the 1900s. I have found PC in such bbls works great. Same in pre Gen5 Glock bbls. I get much better accuracy & cleaner bbls shooting PC in my Glocks v lubed lead.