Golden Saber in 357 mag.

[Paul5388]

When I clocked those at 1620 fps, they were shot out of a 6" Security Six. The 1575 fps loads were clocked out of a 6" M28-2. With a .5 gr reduced load, I clocked 1460 fps out of a 4" M66-2.

I normally load at the original SAAMI pressure specs of 45,000 cup. Regardless of what anyone says, they aren't going to produce the same at 35,000 psi. I've been shooting that Sierra load since 1972 and to the surprise of most, I've never had a problem and no flame cutting!

Here's the M28-2 I bought new in 1972.

This is the same gun after shooting its first 5 H110 loads using 125 gr bullets.

Here's the M66-2 with very little flame cutting (no, I don't shoot H110/W296 in it).

 

[slugfest]

There is quite a bit more barrel diameter shank protruding on your 28 than on a 19, and 2 more inches of barrel helps a lot with slow burning powders like 296 or 2400. That Sierra manual your refer to at 45000 CUP is interesting... I was under the impression that shot guns and pistols were done under LUP and centerfire rifles were measured under the copper cups, though maybe with that level of pressure, 45000, they did measure with copper.

By todays SAAMI loading standards and manuals, those would be considered overloads. Any idea what the ambient air temps were when you cracked off those 1600 fps loads over the chronograph? If you could buy a model 28 back in 1972, you're a little older than me, but I did start reloading a couple years after that.

 

[Paul5388]

The SAAMI pressure spec is still 45,000 cup, or 35,000 psi, according to the Starline brass people.

The ambient temperature was 73 degrees on 1/23/04.

The assumption would be in favor of the 6" being faster than the 4", but that really isn't the case all the time, like this one. Here's some .38 Special data where I used both guns over the chrony.

The purpose of the data was to check identical loads from different lots of powder to see how much validity there is in the "new powder is different from old powder" theory. The old lot of SR4756 isn't from 1956, I misread the lot number, but it is DuPont vs the IMR version I have from 2004.

My first new gun was bought in 1965, when I got out of the Navy.