Jump to content
Brian Enos's Forums... Maku mozo!

Optimum bullet diameter vs barrel bore diameter?


Nimitz

Recommended Posts

Now that I have my Shadow I'm reviewing what I want my load to be. I went to range this morning to chrono 124 and 147g bullet loads to get the same PF so I can do the blind recoil comparison. That got me thinking about optimum bullet diameter as well.

So all things being equal will a bullet that is the same diameter as the bore be better for accuracy or one that is .001 larger than the bore be 'better'. Xtreme bullets come in both .356 and .357 so I'm trying to figure which I should get ...

Link to comment
Share on other sites

Some recommend using oversize bullets to ensures a good gas seal and positive rifling engagement. Schuemann recommends a jacketed bullet of .001 to .002 inches larger, and lead bullets .002 to .003 inches larger for the best accuracy.

Link to comment
Share on other sites

For the "open gun safe" thick plated I'd consider them as like jacketed. For just regular plated somewhere in between but closer to lead. But either way, you aren't going to hurt your barrel. It's going to affect your load data more than anything else.

Link to comment
Share on other sites

Xtreme or those plated bullets distributed by RMR are thickly plated bullets which seem to do best when used as "jacketed" bullets in size and velocity. Plated bullets are more fragile than jacketed so too much oversize can lead to accuracy degradation should the plating be compromised by cutting or other crushing damage if the bullet is too large for the bore. "Slugging" your barrel to determine its actual "bore diameter", or size at the widest diameter in the grooves, is recommended to give a clue as to what bullet sizes to use. However, most modern 9mm bores are held to diameters of .355 or very close to it. When using lead bullets it is a general practice to use bullets of .001" over bore diameter to eliminate leading concerns, though .002 is not unheard of or too large in most guns. You will be experimenting with any bullets you use in your new gun, so your own experience will lead you to choose bullets that shoot well for you in future purchases. This is why we reload... to determine what is best and experiment to find what is better.

Link to comment
Share on other sites

With a fast powder, I'd be concerned with pressure spikes when the .002+ oversize bullet engages the rifling. Especially with jacketed or heavy plated bullets. Likely no problem with lead. I measure my bores and go with .001 over groove size. I haven't run any bullets at the .002+ so just my speculation.

Link to comment
Share on other sites

It depends on what your gun responds to.

Most 9x19 guns I have shot are quite happy with 0.356-0.357" jacketed bullets and 0.356-0.358" lead bullets. However, unless you do a LOT of target shooting over a rest, you'll never know or even be able to see the difference as it tends to be in the 0.1-0.5" smaller group size region and a 3" group is not going to show any difference.

Link to comment
Share on other sites

With the Plated Xtremes I would recommend the .357 bullet, but get some of both and see what works best in your gun. Remember to bell the case adequately and don't taper crimp more than ..376 and run the bullet at least 920 and you should have a good load. Try shooting paper targets at your longest distances ( 50yds) you would have at a match to make sure you don' t have any tumbling.....

DougC

Link to comment
Share on other sites

Bianchi.....which makes me wonder what my other guns and ammo will do at 50..... :roflol: .

Some loads shoot well up to about 30 yds and then blow out at 50. Good to know if you are going to the nationals and they have standards past 25yds....

DougC

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...