Contradicting sources, what to do?

Cerdan

Cerdan

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I have three reloading manuals that I often cross-check before starting a batch of ammo. There are always little variations, and I try to balance them out to determine where to start.

What to do, however, when the data isn't even in the same ballpark? Here's what I found for loading 10mm using v-N350:

Lee's 2nd edition, 180 Grain Jacketed Bullet​
5.9gr (1076 FPS) to 7.2gr (1184 FPS)
Speer #14, 180 Grain TMJ FN/180 Grain GDHP​
8.9gr (1077 FPS) to 9.7gr (1152 FPS)

What the hell am I supposed to do with that? I just loaded 10 rounds with 8.9gr (Speer's minimum, starting load) behind 180grXTPs and now I'm not even sure I should shoot them...

Any advice? Should I assume it's safe 'cause Speer wouldn't've published it if it weren't, or assume it's dangerous because it greatly exceeds Lee's maximum load?
 
What does your third manual say? I would choose the one that the third manual is closer to. (And even consider looking online for a couple more ie. Hornady, Sierra),

A typo in books is pretty common and reload data does change over time (or so I've been told)

I looked at the Lyman 48th edition and V-N350 is not listed, so I can't tell you what it say
 
trubluscrew said:
What does your third manual say? I would choose the one that the third manual is closer to.
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The Hornady manual doesn't specify a load for v-N350, unfortunately...

Shelldrake said:
The Speer manual may be abit hot.
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Understatement of the year!! Dangerously hot, I would say... Thanks for the link to VV's manual, it's a nice resource.

I guess I'll have to pull those bullets and start again. I'm pretty pissed at Speer though... "This book represents years of fine-tuning loads and meticulous testing" my ass. I wrote them asking if they stood by their recommended loads. I'm looking forward to their response.
 
I've had the same thing. I cross referenced 7 different manuals for 300 win mag loads. Some of the starting loads were higher than the max loads in other manuals. I started with the lowest one, worked up in 1/2 grain steps until I got to the highest. As it turns out, my optimal happy load for that particular gun was below the starting loads in 2 of the books.

Even with the highest of the high, I still didn't see any evidence of over pressure.

The golden rule is start low and work up. If you start to see deformation in your case head or the corners of your primers are flattened right out, back off. You've just gone step too far.
 
If you have conflicting data, start low and work up, using a chronograph as a reference. If you start getting hyper velocity speeds, then you usually know you are over pressure, even without pressure signs.
 
Call Speer to validate published data - they'll know if they screwed it up - and they'll tell you about it. I've called bullet/powder manufacturers for non-published load data and they have been VERY helpful (eg - called Hodgdons for cast bullet data for 338 WM - great service - they had LOTS of extra info).

Good luck - you're doing the right thing to ask questions about this!!!

SD
 
Thanks for your comments.

@ricciardeli: Actually, it's when I checked your pages that I started to second-guess the data in the Speer manual and look into other sources. That's a wealth of information you've amassed there!

@blacksmithden & Gatehouse: That's good advice; I think I'll start with the lowest of the low (in this case, 5.2gr) and work up (wish I had a chrony!). Instead of pulling the bullets I've already seated, I'll tuck those cartridges away for the time being. Who knows, I might work all the way up and find they're still within tolerances.

@none: The test firearm in the Speer manual is a M1006, same barrel length as my Colt.

@308BAR & superd222: I agree, 2gr (actually, 3gr!) is a big difference (much more than the usual variation between sources). I wrote Speer and got a very prompt reply.

I was told, first, that their 13th edition didn't specify data for v-N350, so the tests were done recently. They added that the data I quoted from the Lee manual is close to their loads for .40S&W (and, strangely enough, powder loads for v-N350 are almost identical for .40S&W and 10mm in the Lee manual). Finally, I was told the discrepancy could be due to the fact that SAAMI rates the 10mm cartridge at 37,500psi, whereas CIP rates it at 36,200psi... Basically, they stand by their data and recommend I start low.
 
all bullet have different ballistic coefiicient,that's why speer,nosler,sierra, barn's all have different data.
If you shoot sierra bullet use sierra data.
 
pirate122 said:
all bullet have different ballistic coefiicient,that's why speer,nosler,sierra, barn's all have different data.
If you shoot sierra bullet use sierra data.
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It has nothing to do with BC, its how the bullet is constructed (things like bearing surface and manufacturing tolerances on diameter...)

You're right though about the manufacturers. One manufacturer's 180gr. bullet isn't the same as another's 180gr. bullet. They can and often will produce different pressures in the same gun with all other components being the same, with the same powder charge. Further, the results they show may be a lot different in your gun. This is why you always work up a load... And you should always work up the load over again before trying it in a much hotter temperature than you originally tried it in.

Learn to recognize pressure signs and back off when they appear.
 
Is anything else different about the loads at all? Seating depth, or anything like that?
 
I agree with Gatehouse. Err of the side of caution and use the lesser load. If the results suck so what. At least then you'll know.
 
My Speers #13 must be so outdated for it does not list any of the powders you use. If I could have go ahold of a fellow shooter I might have had some fitures for he has one of the rare 40S&W to 10mm revolvers & only uses cast bullets so again a different situation.

I tend to stick with Speers & my guidence books go back to #8 though missing a few & last was #13.
 
Also, Speer brass is much thicker than Federal and Rem and somewhat thicker than Win and CCI. Maybe that factored in Speer could afford hotter loads.
 
"...for Barnes Data..." Barnes bullets are copper not copper with a lead core. That's why you have to use their data.
Loading manuals give different data because the data was tested under different conditions. Temperature, humidity, the firearm can be a 'Universal receiver' and not a regular rifle at all.
A 180 grain bullet is a 180 grain bullet. Who made it doesn't matter. You don't need data for a specific make of bullet. You work up the load to tailor it to your rifle.
 
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