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Loading on the low side


Bench
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I'm working up a new load for 38/125's RN per load data that indicates for 125's a load of 3.9  HP-38 is low end/start load. The load data also indicates a start OAL of 1.060 but my barrel with this new bullet only allows a plunk test of 1.050".  Is there a need to reduce the powder load also or is the start load still within safe bounds? I'm well aware of laddering within load data but haven't encountered laddering up from below "start data". Thanks all!!

Edited by Bench
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43 minutes ago, Helios said:

Why would your target OAL be longer than the OAL at which you plunk?

Because it was late after a full weekend and I had a brain fart!  Absolutely right, but as jack said that much shorter should not matter.

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9 minutes ago, 4n2t0 said:

The OAL's listed in manuals/data is completely useless. Always find your own OAL and start at the minimum charge weight.

This. The OAL in the manuals were specific for the particular gun the testers used during testing. This is the main reason I always do the plunk test to determine the OAL for my loads and then I do my ladder test.

 

Always use a chrono. It’s makes load development a lot safer.

 

 

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19 minutes ago, 4n2t0 said:

The OAL's listed in manuals/data is completely useless. Always find your own OAL and start at the minimum charge weight.

Thanks, I was more concerned about increased pressures that a shorter OAL would produce even at the low charge rates, but herd knowledge has moved me on away from that concern.

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6 hours ago, Bench said:

Thanks, I was more concerned about increased pressures that a shorter OAL would produce even at the low charge rates, but herd knowledge has moved me on away from that concern.

 

Shorter OAL does increase pressure, but you're starting with a mild load already so it's not a big concern.

 

Keep in mind too that if you're using a coated, cast/lubed, or plated bullet the load may generate lower pressure than a jacketed bullet anyway. Also keep in mind that bullet shape makes a huge difference in OAL numbers, and one RN style may need a very different OAL than a RN from a different maker. 

 

Ultimately, you're doing it right. 

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29 minutes ago, Yondering said:

 

Shorter OAL does increase pressure, but you're starting with a mild load already so it's not a big concern.

 

Keep in mind too that if you're using a coated, cast/lubed, or plated bullet the load may generate lower pressure than a jacketed bullet anyway. Also keep in mind that bullet shape makes a huge difference in OAL numbers, and one RN style may need a very different OAL than a RN from a different maker. 

 

Ultimately, you're doing it right. 

This certainly has been a good lesson in OAL variance between RN coated bullet makers...from 1.145  from one maker down to 1.050 from another maker...and in the same gun.

 

Thanks for the +1 on being on the right track.

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The manual states what length they used to load it. It does not say that you have to use *that* same length.

 

Just know that if you load shorter you will increase the pressure, and if you’re not certain? Back down to minimum from wherever you were.

 

Common sense and a combination of experience or caution will get you the rest of the way.

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1 hour ago, MemphisMechanic said:

Common sense and a combination of experience or caution will get you the rest of the way.

The combination of common sense and caution has stood me well for these past 71 years🤣

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