Sizing bullets to cylinder throats

[243winxb]

I'm one who disagrees with the philosophy of "always size to the cylinder throats". I did considerable testing using a Ransom Rest and testing at 50 yards along with shooting off other rests at 25 yards found if the bullets were larger than .002 - over the barrel groove diameter then accuracy really wasn't improved and sometimes was worse. A lubed cast bullet coming out of a .429 groove diameter barrel is going to be swaged down to .424 - .427 because it also has to ride over a thin layer of lube. Thus a bullet starting out into the barrel .002 - .003 over groove diameter is getting sized down .005 - .006 under a lot of pressure very quickly. That can do some bad disfiguring of the bullet, especially the base.

I also found with cylinder throats .003+ larger than barrel groove diameter a harder cast bullet that did not obturate .001 - .002 larger than barrel groove diameter gave better accuracy than a bullet sized .003+ over barrel groove diameter. I also find leading in the throat and barrel to be more a function of the alloy, lube and powder used than "fit" to the cylinder throats.

Yes, I know many will disagree here but that's what I've found. I shoot .430 sized bullets in my Ruger and Hawes 44 Magnum revolvers with excellent accuracy and no leading. The Rugers throats are .432 and the Hawes are .433. I actually shot 5000+ cast bullets (COWWs) sized .429 and lubed with Javelina through the Hawes with excellent accuracy and no leading before I read I was doing it all wrong. Testing has shown bullets sized .431, .432 and .433 shoot no better (the .433 shot poorly as the barrel groove diameters are .429 in both revolvers) than the .429 and .430. I use .430 sized 44 bullets now simply because that size shoots best in my 44-40 Chiapa M92 which, of course, does not have cylinder throats.

As to the "constriction" I have fire lapped a couple revolvers and it did work as with megasupermagnum. However, I've also found that simply shooting a couple hundred jacketed bullets with top end loads for the cartridge usually accomplishes the same thing.

I have not seen this in recovered bullets?

swaged down to .424 - .427 because it also has to ride over a thin layer of lube.

I need to check it out.

My pistol bullets are sized to groove diameter. 358,452, 430

[Larry Gibson]

That is with a lubed bullet. PP'd and PC'd bullets are another story.