Differences in Load Data

This section is for reloading and ammunition only, all loads found in here are used strictly at your own risk, if in doubt ask again.
All handloading data posted on Full-Bore UK from 23/2/2021 must reference the published pressure tested data it was sourced from, posts without such verification will be removed.
Any existing data without such a reference should treated as suspect and not used.

Moderator: dromia

Forum rules
All handloading data posted on Full-Bore UK from 23/2/2021 must reference the published pressure tested data it was sourced from, posts without such verification will be removed.
Any existing data without such a reference should be treated as suspect and not used.

Use reloading information posted here at your own risk. This forum (http://www.full-bore.co.uk) is not responsible for any property damage or personal injury as a consequence of using reloading data posted here, the information is individual members findings and observations only. Always verify the load data and be absolutely sure your firearm can handle the load, especially older ones. If in doubt start low and work your way up.
Post Reply
Message
Author
User avatar
RDC
Posts: 1145
Joined: Sun May 24, 2015 12:14 pm
Contact:

Differences in Load Data

#1 Post by RDC »

I've noticed quite a bit of a difference between two sources of load data for the same bullet and powder. In this case, .223 cartridge, Hornady V-Max 53gr with N133 powder.

The Hornady 10th Edition give 20.6gr thru to a max of 23.0gr, COAL 2.24in
The VihtaVuori website gives 22.8gr thru to a max of 24.7gr, COAL 2.256in

Now, my question is how do you know which to follow? Both are published data, but the start load from Viht is near the stated max load from the Hornady data. The Lyman 50th Edition doesn't have data for this bullet to cross-refer. Where else would you go to corroborate either load data?

Any advice would be welcome. thankssign
User avatar
dromia
Site Admin
Posts: 19964
Joined: Sat Nov 06, 2010 4:57 am
Home club or Range: The Highlands of Scotland. Cycling Proficiency 1964. Felton & District rifle club. Teesdale Pistol and Rifle club.
Location: Sutherland and Co Durham
Contact:

Re: Differences in Load Data

#2 Post by dromia »

This is quiet common as no two testers test the same so there will be variation in results.

Firstly the seating depth of the Hornady loads is greater than the Vhitauvuori, then there are all the other variables, test barrel length, chamber size, powder batch, etc. etc.

Personally I will always start with the lower set of data and work up from there.
Image

Come on Bambi get some

Imperial Good Metric Bad
Analogue Good Digital Bad

Fecking stones

Real farmers don't need subsidies

Cow's farts matter!

For fine firearms and requisites visit

http://www.pukkabundhooks.com/
User avatar
RDC
Posts: 1145
Joined: Sun May 24, 2015 12:14 pm
Contact:

Re: Differences in Load Data

#3 Post by RDC »

dromia wrote:This is quiet common as no two testers test the same so there will be variation in results.

Firstly the seating depth of the Hornady loads is greater than the Vhitauvuori, then there are all the other variables, test barrel length, chamber size, powder batch, etc. etc.

Personally I will always start with the lower set of data and work up from there.
Thanks for the response Dromia!

I loaded to the Hornady data, so I'll see how it goes. cheers
User avatar
Mattnall
Site Supporter Since 2016
Posts: 2858
Joined: Wed Mar 06, 2013 5:32 pm
Home club or Range: Harlow TAC, NRA, BSRC
Contact:

Re: Differences in Load Data

#4 Post by Mattnall »

Various testers will only report on their findings, and their testing will be different to others and will start and stop at different loads, recommendations will be made accordingly.
I wouldn't trust loads using third party data, sometimes the data are mistyped.
Arming the Country, one gun at a time.

Good deals with Paul101, Charlotte the flyer, majordisorder, Charlie Muggins, among others. Thanks everybody.
Laurie
Posts: 650
Joined: Mon Dec 20, 2010 8:20 pm

Re: Differences in Load Data

#5 Post by Laurie »

This piece from Sierra Bullets summarises the main reasons:

http://bulletin.accurateshooter.com/?s= ... mit=Search

Case capacity has a major effect and 223 Rem sees a considerable variance across makes (and even periods - eg Lapua went to thinner wall / higher capacity manufacture some years ago). There is a table in here of 223 case weight / internal capacity which although rather old is still useful.

https://www.accurateshooter.com/cartrid ... es/223rem/

Powder and bullet manufacturers may make certain assumptions when compiling testing loads and compiling data. Because of the large variety of 223 brass around - commercial and arsenal - and differences between makes, the manufacturer may build a 'safety discount' in, reducing charges across the board. Printed manuals usually say somewhere in the 'How to reload' section and in Notes to reloading data, that those data apply only to the exact components listed. However, many users either don't understand the issues, or never read the 'small print' anyway, or just say 'B*gg*r it! - an xxgn bullet is the same whoever made it, likewise there's no difference between makes / models of primer' etc, etc. So the manual compilers add a little safety in. Conversely, some use the lowest possible capacity case available and say so in the cartridge notes. For instance, Speer deliberately chose Israeli IMI 223 brass for its tests loads for many years as this is a very heavy / low capacity design. (Using thin Winchester brass could add as much as 1.5gn to allowable max loads.)

However, with a few exceptions such as Speer, we don't know whether the manufacturer has or hasn't built in any such adjustments and it's extremely unwise to assume they have (as some handloaders do as a matter of course!) How often do you hear the comment on the range that Vihtavuori loads are always lower than they need be so you can play fast and loose with them. Some Viht data are 'modest', indeed inexplicably so, but not all!

Then Hornady is American and Vihtavuori is European working with different standards bodies - SAAMI and CIP. This may or may not affect the specs for the industry-standard test barrels used in their load development. Certainly, the two use different pressure measurement techniques even though both are Piezzo crystal based. In the case of 223, SAAMI MAP is 55,000 psi whilst CIP is 43,000 bar / 62,366 psi. Even with modest differences in measuring methods, this standards difference in itself would make CIP-compliant Viht maxima higher than Hornady's SAAMI equivalent. That's why there are two QuickLOAD 223 entries.

There is a growing gap too between US loads for some cartridges largely used in AR type semi-auto gas-guns and the same numbers when used in bolt-actions. Sierra produces two sets of 223 load tables for this reason. Those cartridges based on the 7.62X39mm M43 case design - Grendel, new 6mm Hornady ARC etc have modest SAAMI MAPs - 50,000 and 52,000 psi - despite people knowing the parent PPC case is a strong design. It's because three-quarters or more users in the US will shoot these numbers in AR-15s and the larger diameter case-head (over 223) makes them marginal for the AR-15 bolt size / strength. Put the same cartridges in a bolt-action, even the small Cz527 and Howa Mini 1500 and they'll take another 5-7,000 psi easily and safely.

At the end of the day, loads tables aren't tablets written on stone. There are so many variables involved with both the user's firearm and ammunition components, even the effects of the environment they're used in - ie ambient temperatures - that they are advisory rather than 100% prescriptive. It is up to the user to start low and work up in small steps, look for pressure signs, and stop / move back down a bit when things start to look too 'hot'. Given the improvements and prfice reductions in chronographs, use of one really is mandatory too nowadays. If you're 'getting higher MVs than you should', then it's a pretty fair bet you're also producing higher pressures.
User avatar
RDC
Posts: 1145
Joined: Sun May 24, 2015 12:14 pm
Contact:

Re: Differences in Load Data

#6 Post by RDC »

That is an excellent post, thanks Laurie.
borbal
Posts: 5
Joined: Sat Aug 08, 2020 8:42 am

Re: Differences in Load Data

#7 Post by borbal »

Laurie wrote: Then Hornady is American and Vihtavuori is European working with different standards bodies - SAAMI and CIP. .
Curious then that Vihtavuori do not use the standard CIP barrel lengths (600mm for 'regular' cartridges and 650mm for magnums). Any notions why that might be?
Post Reply

Who is online

Users browsing this forum: No registered users and 13 guests