slugging barrel of cz accushadow results and bullet size question

[PaladinPrecision]

So I used one of my BBI 0.356 bullets to "slug" my barrel and came up with 0.3560 on the "grove". But I don't think it actually touched the  outer diameter groove. What I got out of it is that I will likely need to order oversized 0.357 bullets for this gun? I will probably break out the torch and some lead later and cast a slug with a 9mm case and retry and report in. But I was hoping to hear from guys that have done it before and are also accuracy nazi's like myself. Darrell etc feel free to chime in if you have constructive criticism... ie don't reply if you are just going to comment about wasting time.

[jcc7x7]

Round balls for black powder guns, will usually expand to groove diameter.

Or

Get a box of 358 dia. Lead bullets.

To push through

[PaladinPrecision]

Kinda figured 357, but that works. So if my barrel slugs 357, i should use 358 bullets correct?

 

[jcc7x7]

That is the old school general thought process.

I've gone to buying 100 round sample packs and seeing what shoots best out of the gun

As an example:

I've got a 357 S&W 627 Revo that shoots 356 Bayous great, also shoots 358 bayous and 357 Blue Bullets into the same 3" group at 50, yes 50yds from a bagged rested gun.

My 1911's and Sig 226's shoot 356 and 358 coated into the same group

May Tanfo 9 likes 358's also

So I shoot 358's out of all of them to cut down on different bullets I have to stock etc.

My open gun shoots the 358 coated without a lot of garbage in the comp but likes 356 PD's as well

So all that to say it may be simpler to try the bullets that you like and have the maker size them to 357 or 358 and make sure they "plunk" at the oal you want, than doing all the figuring and then still having to test.

I went with going directly to testing different bullets until they made PF and were accurate, instead of slugging and then testing etc

[PaladinPrecision]

Sounds fair, thanks for the information!

[PaladinPrecision]

I talked to the owner of BBI and he said that there might be barrel springing accounting for the 0.0005-0.001 inch I was expecting.

[jim vaughan]

Use pure lead to slug your barrel. Anything else will spring and give you false information.

 

[IDescribe]

Correct, springback  is a possibility with alloyed lead. 

 

 

Another option, though. If the measurement you get from slugging tells you that you should shoot .356, but through testing you found your pistol did best with .357, would you shoot .356 anyway?  Same for .357 VS .358?    

 

And if you would shoot what shoots most accurately anyway, regardless of what the slugging told you, wouldn't the more relevant test be to buy some 124/125gr coated lead bullets sized 356, 357, and 358, and simply see what does best in the pistol? 

 

ACME has good bullets at .356.  BBI tend to be a little oversized at .357, even though they say they're .356.  You can order .357 from Ibejiheads, I think.  And you can get .358 from Blue Bullets under their .38/.357 caliber offerings. 

[PaladinPrecision]

I measured the BBI bullets and they averaged about 0.3563 . They shoot fine, I was just looking to see if I should bother switching for "peak" accuracy. Not that my accushadow is inaccurate. 

I do plan on doing more accuracy testing. I have a ransom rest that I just revised the base on. Bonded sheets of wood to make a 2 1/2 inch thick base thanks to input from the late Mr Jerry Keefer. I have a great match load for it with jacketed bullets, trying to optimize the cheap coated/ low cost powder loads if possible.