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Confidence in dimensions between reloading manuals
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Using the Vihtavuori (3rd Edition) I happended to noticed some inconsistencies with case measurements.

The 30-06 load table depicts the cartridge case and bullet with both Metric & Avoirdupois (English) units. However, based upon other manuals I have here (Hornady, Speer, etc) the basic case dimensional measurements do not jibe. The VV manual depicts higher case dimensional values.

I've come to know 30-06 bullets to measure .308 in diameter for example, however VV shows it as 7.85mm or .309.

When I ran the numbers myself, its result set became 7.82mm (.308 x 25.4 = 7.8232 or conversely 7.82 x 0.39337 = 3.0761534) as opposed to the published values (by the way, other parts of the case were inconsistent as well) I have limited the scope however, only to the bullet's diameter and its seating depth.

VV appears to be highly respected and was wondering why would these dimensions be depicted so inconsistient to the other documented versions? Are the standards between firearms significantly different between us & the Europeans (I wouldn't think so, especially if a US version is used)?

It is noteworthy to mention that the load charges themselves appear to covert back & forth properly (specifically for 30-06).

What are your thoughts or direct experiances with these published differences? Is it even an issue worthy of concern?

Best regards,
Alex

 
Posts: 902 | Location: USA | Registered: 01 March 2001Reply With Quote
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quote:
Originally posted by Alex Szabo:
Using the Vihtavuori (3rd Edition) I happended to noticed some inconsistencies with case measurements.

The 30-06 load table depicts the cartridge case and bullet with both Metric & Avoirdupois (English) units. However, based upon other manuals I have here (Hornady, Speer, etc) the basic case dimensional measurements do not jibe. The VV manual depicts higher case dimensional values.

I've come to know 30-06 bullets to measure .308 in diameter for example, however VV shows it as 7.85mm or .309.

When I ran the numbers myself, its result set became 7.82mm (.308 x 25.4 = 7.8232 or conversely 7.82 x 0.39337 = 3.0761534) as opposed to the published values (by the way, other parts of the case were inconsistent as well) I have limited the scope however, only to the bullet's diameter and its seating depth.

VV appears to be highly respected and was wondering why would these dimensions be depicted so inconsistient to the other documented versions? Are the standards between firearms significantly different between us & the Europeans (I wouldn't think so, especially if a US version is used)?

It is noteworthy to mention that the load charges themselves appear to covert back & forth properly (specifically for 30-06).

What are your thoughts or direct experiances with these published differences? Is it even an issue worthy of concern?

Best regards,
Alex



Alex I wouldn't worry about it, measure your own cases fired in your chamber and do a chamber cast and/or use a chamber over all length gauge to determine your guns chamber measurements, all measurements are a compromise of SAAMI and other bodies allowed tolerances of the same name caliber, the go/no go and field gauges are one example of these tollerance allowances and some are larger than others but most of the time they are not of much difference in important safety areas but there are differences, good luck and good shooting!!!
 
Posts: 687 | Location: Jackson/Tenn/Madison | Registered: 07 March 2001Reply With Quote
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If you really want to see some difference between metric and the imperial, check the Vihtvuori on line manual for 6.5x55 and N150 for 100gr bullets. Same bullet, same overall length.

Imperial version 41.9gr
Metric version 43.4gr

Conclusion metric loaders have stronger guns?!? I have to say this is not the first time I have noticed anomolies in Viht data - I still use the powder but I am careful.

[This message has been edited by 1894 (edited 05-23-2001).]

 
Posts: 2258 | Location: Bristol, England | Registered: 24 April 2001Reply With Quote
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quote:
Originally posted by 1894:
If you really want to see some difference between metric and the imperial, check the Vihtavuori on line manual for 6.5x55 and N150 for 100gr bullets. Same bullet, same overall length.

Imperial version 41.9gr
Metric version 43.4gr

Conclusion metric loaders have stronger guns?!? I have to say this is not the first time I have noticed anomalies in Viht data - I still use the powder but I am careful.

[This message has been edited by 1894 (edited 05-23-2001).]


Hello 1894,

Yes, I have looked at it (not on-line however) on pgs 151...153 and here are the results:

100 gr HP Sierra
grams grains g->gr gr->g
N140 2.59 40 40.0 2.59
N540 2.58 39.7 39.8 2.57
N150 2.64 40.6 40.7 2.63
N550 2.76 42.6 42.6 2.76
N160 3.07 47.3 47.4 3.07

The first 3 columns are published, and then the subsequent are calculated by me using the published values (col 2 x factor and col 3 x factor respectively). Please notice that N540, N150 & N160 have inconsistencies. In addition, on page 151, the columns which depict the charge between the two units are also inconsistent.

I do not as sure about your conclusion however. I think it is a Quality Assurance issue on the part of VV. I think as careful a records as they maintain, there were divergent scenarios (between two or more departments) combined together which are based on different perspectives. Not all is equal when that occurs.

Problem is, it certainly does not instill confidence in their materials. I wonder if they are even aware of these inconsistencies?

Thanks for the heads up.

Best regards,
Alex

 
Posts: 902 | Location: USA | Registered: 01 March 2001Reply With Quote
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Allthough I agree published data should be clear and accurate I think this is getting a bit out of hand, I do not decry differences of 0.1grains which are not even reliably measurable by most scales. You will note that the constant is 15.432 which when applied to a 0.01gram figure creates an interesting rounding question, is .015432grains to be .01grains or .02grains? Whichever, it is is out by nearly as much as it is possible to be. It all makes not a blind bit of difference.

VV powders have a substantial match rifle following in the UK and you only get that by producing the goods. I am more worried about faster lots of powder and differences of 1.5gr which I intend to e mail the factory about. I will let you know their response.

Good luck in working up that humour (grin) and get yourself a metric rifle for some added safety margin (grin)!

PS for your sanity I do not reccomend weighing bullets or cases........

1894

 
Posts: 2258 | Location: Bristol, England | Registered: 24 April 2001Reply With Quote
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quote:
Originally posted by 1894:
<snip> I do not decry differences of 0.1grains <snip>

I am more worried about faster lots of powder and differences of 1.5gr which I intend to e mail the factory about. I will let you know their response.

<snip>


For the most part, that would probably be okay. In this instance, VV publishes maximum values in their onset. I think your statement is true if and only if the maximum pressure of the firearm is not met nor exceeded (it is just what I happen to subscribe to however in terms of process & quality). Thus far, I've had very excellent results with that Lapua Scenar 180 gr bullets with the VV N150 & LC cases.

Very excellent points! I wholly agree with you on paying attention to details! It boils down to doing homework before proceeding.

Perhaps you can create an entrepreneurial venture in creating and marketing a metric Mauser !

Best regards,
Alex

 
Posts: 902 | Location: USA | Registered: 01 March 2001Reply With Quote
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