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Old January 28, 2013, 11:03 PM   #1
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is it safe to use magnum primers in 38 spl ?


I can't find any small pistol primers anywhere. My normal load (for a 1962-vintage S&W model 10 in 38 special) is 3.2 grs of Bullseye. would it be safe to load CCI magnum small pistol primers with this load? Should I reduce the load to 3 or even 2.5 grains? I don't want to stress the pistol as I am quite fond of it.

would such a load be safe for a model 36 snubbie as well?
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Old January 28, 2013, 11:05 PM   #2
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Not saying that it is the right thing to do and not recommending it, but I have used them several times without a problem, but I backed off the powder charge about 10%.

Last edited by shootniron; January 29, 2013 at 12:40 PM.
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Old January 29, 2013, 12:22 AM   #3
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I just shot some today in 38 spl out of my 357
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Old January 29, 2013, 07:22 AM   #4
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This is where a chronograph would come in handy. Just chrono your known loads with a standard primer and then go for the same velocity with magnum primers. Eezy Peezy.
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Old January 29, 2013, 11:42 AM   #5
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Drop your load 10%, then work back up.

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Old January 29, 2013, 12:06 PM   #6
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I use small rifle primers for mine. Start at the starting load work back up to your present load watching for pressure signs.
No matter how many times you do it and nothing happens it only takes something going wrong one time to kill you.
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Old January 29, 2013, 12:09 PM   #7
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Generally I just reduce loads by 1/2 a grain and call it good.
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Old January 29, 2013, 12:41 PM   #8
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Drop your load 10%, then work back up.
This is the best thing to do.
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Old January 29, 2013, 02:12 PM   #9
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No! Stop what you're doing and send me all those dangerous magnum primers. I'll dispose of them safely
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Old January 29, 2013, 02:43 PM   #10
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You didn't say if you were shooting 148 grain wadcutters seated flush with the case mouth or some other bullet seated further out. The difference it makes is that the former doesn't leave a lot of empty space in the case where the latter would. In the latter instance you may actually find you get better accuracy from magnum primers just because the do a better job of pressurizing all the empty space. A magnum primer behind a 158 grain round nose bullet seated to the max .38 Special COL is probably making lower pressures than standard primer behind the deeper seated 148 grain LWC is.

Broadly speaking, though, the advice to reduce charge is good. In .223 I've seen magnum primers make the equivalent pressure difference of about a 4% increase in powder charge, so I only drop rifle loads 5% when making the small rifle primer switch. The smaller volume of the handgun, though, probably makes the 10% reduction more reasonable to do. If it were a rifle cartridge I'd then say to roll six rounds that go up in 2% steps, but that's too small for most scales to weight in your case. So I like the idea of just dropping the load half a grain, then going back up in 0.1 grain increments to see if you can tell the difference.

In the end it may make no difference at all. The primer may just unseat the bullet sooner, leaving the net peak pressure largely unchanged because the powder starts building pressure in a larger volume. Can't know until you try, though, and that's why the reduction and build up is a good plan.

As also suggested, a chronograph would make this a lot easier.
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