Lead Bullets and Colt Revolvers

[ADR]

I've got two Colt DA Revolvers, a 1977 vintage Python 6 inch barrel and a 1960 vintage ".357" with 6 inch barrel. I got around to slugging the cylinder throats and the barrels of each gun and I'm seeking advice on what would be the best lead bullet diameter to use in order to get the best performance out of these revolvers.

The Python Cylinder Throats measure .359 with micrometer and the slug pushes through each chamber with light to moderate push with a wood dowel.

The ".357" Cylinder Throats measure .3585 the slug pushes through each chamber with light to moderate push with a wood dowel.

The barrels came out tighter---I've been told Colt Barrels are tighter that S&W--I slugged the Python barrel and it measured the slug at its widest point with a micrometer and it was .355, the ".357" barrel was the same at .355

My intent is to shoot only .38 Special handloads out of these guns. 158 grain bullet or 148 grain wadcutter bullet. Standard velocity 750-800 FPS. It my understanding that matching bullet diameter with the cylinder throats is very important. My question is--should I go with .358? .359? or even .360?

[DougCarden]

First off I would say that I haven't seen a Good Revo NOT shoot the .358 sized bullet.

Having said that, every gun is different.

I would get with your bullet caster, and get 100 of each bullet, sized .357 and sized .358.

Load them up, and then spend the afternoon shooting groups and see what your gun likes.

Take paper plates, they are cheap. Shoot your 6 shot group, write down the load and bullet size, then keep at it.

When you go home break out the calipers and measure the groups. Look for clusters of 3-4 shots, you will know if you yanked the trigger or not.

There may not be a difference, but sometimes a load stands out, and you will know it when you see it.

Good luck,

DougC

[G-ManBart]

I've got two Colt DA Revolvers, a 1977 vintage Python 6 inch barrel and a 1960 vintage ".357" with 6 inch barrel. I got around to slugging the cylinder throats and the barrels of each gun and I'm seeking advice on what would be the best lead bullet diameter to use in order to get the best performance out of these revolvers.

The Python Cylinder Throats measure .359 with micrometer and the slug pushes through each chamber with light to moderate push with a wood dowel.

The ".357" Cylinder Throats measure .3585 the slug pushes through each chamber with light to moderate push with a wood dowel.

The barrels came out tighter---I've been told Colt Barrels are tighter that S&W--I slugged the Python barrel and it measured the slug at its widest point with a micrometer and it was .355, the ".357" barrel was the same at .355

My intent is to shoot only .38 Special handloads out of these guns. 158 grain bullet or 148 grain wadcutter bullet. Standard velocity 750-800 FPS. It my understanding that matching bullet diameter with the cylinder throats is very important. My question is--should I go with .358? .359? or even .360?

The best situation is where the throats are .001" larger than the bore and you size the bullets to be either the same diameter as the throats, or .001" larger. That seals the expanding gases behind the bullet, and allows the bullet to swage down .001" as it enters the barrel and have a good seal to the bore.

If I was loading for those two guns, I'd probably try sizing the bullets to .359" first, and see what happens.

The big problem comes with (normally) really old guns that have the dimensions for the throats and bores mismatched with the throat being smaller than the bore....the bullet is smaller than the bore from the start, and that's not likely to work well. Your guns don't seem to have that issue, so they'd probably shoot fine with any of the sizes you mentioned. R,

[anachronism]

Yup, I'd start with .359 too. .358 may work okay, but it sounds like they should both work well at .359. Now, don't go buying super hard bullets to shoot at such low velocities. Shop around for something around a brinnel hardness of around 10. Most leading is caused by a combination of bullets that are too small, and too hard. Some of the guys that also offer cowboy action bullets might have exactly what you need.

[DCS44256]

Good notes above - I shot .357 and .358 sized cast bullets in my Python and "Model 357" with great results. They had the tight barrel but I do not recall the throat measurements. .358 should work with softer bullets, not the "hard cast" that most people sell, for your application.