All Brass Is Not Equal

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Aug 20, 2006
Recently I've been shooting a new Bobby Tyler 45 Auto Rim that was built from the ground up on a Ruger OM 357 frame. The gun is shooting great with 3 different bullets & powders but I'm not surprised.
What did surprise me, & I keep forgetting to mention it is, the difference in brass. Many times, six gun prophet John Taffin has cautioned against mixing different brands of brass, especially in the smaller calibers or capacities. A 45 Auto Rim is basically the same capacity as a 45 Auto, not really a lot of powder. In a 9mm it can really become a problem, trust me.
I started out from day one using new Starline brass, which is known to be of high quality & lasts for a long time, some of mine has now been fired 4 times & is still going strong. Also on the shelf was some factory PMC 45 Auto Rim so I shot some of it and then weighed both cases, Starline & PMC, what a surprise!
The Starline tipped the scales at 88 grs, while the PMC weighed in at 99 grs, yikes! You can see that if a person worked up to what you consider the mythical maximum load using the Starline brass & then dropped the same charge into the PMC brass you could very easily get a pressure spike, especially with a fast burning powder.
That's why you don't use someone else's loads, ever without working up from 2-3 grs below. Changing anything always changes everything!



Ruger Guru
Sep 18, 2002
True comments above.

For many years,, I used "mixed" brass in most of my handguns. My loads were almost always worked up for accuracy & rarely got near the maximum charges.
But,, I would often get a good load, showing excellent results,, only to have that pesky flyer, or a group that just seemed too big for what I'd been getting.
Especially when I went to longer distances.

Well, I finally started (years ago) sorting my brass by brand & all. And with it,, I saw immediate changes in groups & accuracy. I recall one time,, shortly after I'd loaded the exact same powder, bullets & primers in different cases,, and kept them separate, shooting groups at 100 yds. When I saw the results,, standing there all by myself,, I muttered; "You stubborn dumb***!"
Afterwards,, when I would load ammo, and check stuff with my Chrono,, I saw changes in the numbers. The consistency was better.

But,, I also know that if you are loading ammo for casual plinking & not near the max charges,, and are shooting at closer distances,, (example; making plinking ammo for the kids,) you can use mixed cases & most will be just fine. WITH the exception of small cases, with low volume, & fast powders. Something like .38's, .357's, .41's, 44's, & .45's,, are usually much more forgiving.
Semi-auto calibers like 9mm, .40 S&W, .45 acp, can be less forgiving.

I've never loaded for or used much .45 Auto-Rim,, so my experience there is almost non-existent. BUT, knowing how it's a lot like a .45 acp,, I'd approach it the same way as I would the acp stuff.

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