Help selecting the right sized bullets

[J_Allen]

So I need a little help trying to figure out the optimal size bullets for my 627. I have used Bayou in the past, 160 gr RN. I was going to try Ibejiheads, and the same profile has three different sizes: .356, .357, .358. I measured the Bayous I had and they came out at about .3575. Then I used my calipers to check the cylinder throats, and got .3565. So I think I should use .357 sized bullets - I figure anything larger than the throats will get sized down anyway, but I don’t want to go lower than that, correct?

[Distant Thunder]

Rather than the calipers, you may want to measure your cylinder throats with a set of pin gauges. They may provide a more accurate measurement. Don't be surprised if you find the cylinder throats to be different sizes.

[J_Allen]

Thanks. Didn’t know if slugging them with soft lead would be better, but used calipers since that is what I had on hand.

[jcc7x7]

The older I get the less I measure cyl and bores.

I buy a sample pack of each size and shoot them.  The most accurate with least amount of barrel deposits wins!

FWIW

[pskys2]

Most 357/38 lead/coated bullets are nominal .358.  Better too large than too small. 

My thought is if you had good accuracy with Bayou's (.3575 were .358 I'm sure) you should stick with .358 from a new supplier and see if they 1) measure the same and 2) give as good accuracy.  If they don't you might want to go back to Bayou's.  If they do then try another small pack at .357 to see if they give any better accuracy.

Try to keep changes to 1 at a time or you won't know what is causing an issue, or not.

[Mcfoto]

My 627 loves Blue 147's which I believe are sized at .358.

[alecmc]

.358 ibejis for me 160gr in my 627s

[Joe4d]

Bayou has a 10% off sale,,, why change ?  what are you trying to improve on ? 

[MikeBurgess]

for what its worth, I have had really good luck with 358 coated bullets in my 627s

just tried some of the ibejiheads 165s and from my wifes gun while sighting in her red dot I was getting a 3" 8 shot group off hand, 

[J_Allen]

Thanks everyone for the advice. The reason I was thinking of switching was to reduce the bulged brass I get when seating the larger diameter bullets. I haven’t had a ton of trouble reloading, but do notice that my snap caps fall into the cylinder much better than my loaded rounds do. I didn’t know if the bullet diameter was a possible factor for this or not.

[PatJones]

I've always shot .358s. I like a crimp groove, so I'm shooting the coated 158s from S&S.

I don't measure throats or slug barrels anymore. It's only a problem if your throats are smaller than your barrel. If you've got one that leads with everything, sell it.

[pskys2]

13 hours ago, J_Allen said:

Thanks everyone for the advice. The reason I was thinking of switching was to reduce the bulged brass I get when seating the larger diameter bullets. I haven’t had a ton of trouble reloading, but do notice that my snap caps fall into the cylinder much better than my loaded rounds do. I didn’t know if the bullet diameter was a possible factor for this or not.

In 38 Short Colt that bulge is more due to the depth of the bullet.  You can load longer or try a lighter bullet or go to a lighter jacketed bullet.

I notice that Starline 38 Short Colt gives me occasional trouble with .358 160 grain bullets if loaded to less than 1.160".  I load to 1.170"+ and have no more issues.  I've tried as far out as 1.250" but didn't like it that far.  

It has to do with the thickness of the web of the case head in a short case and the taper of it to the case mouth, the 9mm has the same issue.

[J_Allen]

3 hours ago, pskys2 said:

In 38 Short Colt that bulge is more due to the depth of the bullet.  You can load longer or try a lighter bullet or go to a lighter jacketed bullet.

I notice that Starline 38 Short Colt gives me occasional trouble with .358 160 grain bullets if loaded to less than 1.160".  I load to 1.170"+ and have no more issues.  I've tried as far out as 1.250" but didn't like it that far.  

It has to do with the thickness of the web of the case head in a short case and the taper of it to the case mouth, the 9mm has the same issue.

Thanks so much for that explanation! I’m not going to worry about it as much anymore.

[BallisticianX]

Calipers can not adequately measure an inside bore as the jaw flats dont hit the exact crown of the radius. As another said using pin gauges is the correct tool. You can also use an adjustable hole gauge you can set and then measure with a mic. Optimum conditions are the throats to be the same dimension of the bullet and no larger than .001" over, and the bullet sized to seal the guns bore diameter. For example if you have a .357" bore you'll want bullets sized between .357" & .358" for lead/standard plated and .357" for jacketed and any heavy plated. So therefore your throats would be best at .358" to best use a .357 or .358 bullet. Now if your throats are .3565" and your bore remains at .357" than you may be able to get away with a .357 bullet but a .358" will induce leading and possible accuracy degrading. Without slugging your bore Id say find the throat diameters and get the nearest bullet diameter slightly larger and run them and check for accuracy and leading. If it seems fine then be done with it. If its not and you want to remedy it then here's my suggestion. Get yourself a couple hones from brush research and work them to out (youll need a pin gauge to check your progress) I myself open them up to .358" to allow for .358 lead bullets but found no issues with accuracy or velocity when I shoot .357 jacketed thru them.  

Edited July 17, 2019 by BallisticianX

[J_Allen]

Thanks for the technical insight. I think I’ll stick with the .358 sized bullets. If it ain’t broken, don’t fix it.