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Variation in load data?

P

pepperbelly

Sergeant
Full Member
Minuteman
Aug 7, 2006
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Fort Worth, Texas
I have been working up a load for my LR308 SASS. I have noticed a large difference in load data between my Sierra manual and Hogden's online data.
My Sierra book shows a starting load of 36.3gr and a max of 41.7gr.
The Hogden online data shows a starting load of 42.0gr and a max of 45.0gr. C. I assume the C means a compressed load.

The Hogden starting load is over the Sierra manual's starting load. What am I missing?
 
Re: Variation in load data?

You're missing the fact that Sierra is much more conservative in what they are printing. All published data from bullet and powder manufacturers shows charges that are less than 100% SAAMI pressure limits. It's a "fudge factor" to allow for lot to lot variables. Also, all the other factors that can effect pressures that are beyond the publisher's control.
 
Re: Variation in load data?

I always use Hodgdon data. It's never let me down.
 
Re: Variation in load data?


I have always been taught to go by the book and never exceed published load data. I know they change data over the years due to slight changes in powder, bullet design, etc.
Since the data Hogden has on their website would also be considered to be published the wide variance is worth being concerned about.

I found a very accurate load today. 41.0gr of Varget. That is inline with the Sierra data but much lower than the Hogden starting load. I was also taught to not load under a minimum published load. That is why I am concerned.
 
Re: Variation in load data?

Both sources have a 5g spread are the components identical in both books?
 
Re: Variation in load data?

I am guessing you are loading the 175/178grn bullet from the load listed. Most people I know find a Varget, which I am also assuming from the load weight, load weight for those bullets between 43.5 and 44.5grns. You might have hit a low accuracy node but if you work up you might find another that will give you more velocity. Just work up slowly for safety.

Of course if you are happy with that lower charge for what you do then stick with it.
 
Re: Variation in load data?

I am loading the 175gr SMK. I started with 43gr of RL-15 and noticed shiny marks from my ejector on the brass- I am using Federal brass. I have since been told that Federal brass is soft, and that my SASS tends to chew up brass. That is why I looked for a lower load- thinking I was seeing signs of overpressure.

I also seem to remember that a load that may be good in a bolt rifle may be overpressure in a semi-auto. I don't know how to check that other than looking for signs of pressure.

I may look for a higher load that is as accurate, but for now this load will work. I mainly wanted to make sure it is safe since it is less than the Hogden mimimum load.


edited to add: Load specs- 175gr SMK, 41.0gr Varget, Federal brass, CCI LR primer.
 
Re: Variation in load data?

Pepperbelly,

All reloading manuals are simply a report of what components were used, and the results obtained. None are "wrong" per se. The differences you see are simply the reuslt of different lots of powders, lots of bullets, primers and cases, even if two different manuals are using ghe "same" components. Throw in the differences cause by different makes of brass, types of primers, chambers int he test firearms, and you get this type of variance between sources. Think of it this way; it's very good insight in just how much substituting a different component or two can alter the "same" load.

For what it's worth, the normal, everyday accuracy QC load for both 168 and 175 SMKs in the Sierra test range, was 40.7 grains of Varget, Federal brass and Federal 210M primers. Gave about 2575fps in the test barrels and always delivered excellent accuracy.
 
Re: Variation in load data?

even if two different manuals are using ghe "same" components. Throw in the differences cause by different makes of brass, types of primers

Kevin, I thought cases and primers were "components" (lol) even twist rate would have some pressure effect.
 
Re: Variation in load data?

Twist rate actually plays a very minor role in pressure, usually well under one half of one percent, even in extreme examples. Throat length and leade angle on the other hand . . ..
 
Re: Variation in load data?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Kevin Thomas</div><div class="ubbcode-body">Pepperbelly,

All reloading manuals are simply a report of what components were used, and the results obtained. None are "wrong" per se. The differences you see are simply the reuslt of different lots of powders, lots of bullets, primers and cases, even if two different manuals are using ghe "same" components. Throw in the differences cause by different makes of brass, types of primers, chambers int he test firearms, and you get this type of variance between sources. Think of it this way; it's very good insight in just how much substituting a different component or two can alter the "same" load.

For what it's worth, the normal, everyday accuracy QC load for both 168 and 175 SMKs in the Sierra test range, was 40.7 grains of Varget, Federal brass and Federal 210M primers. Gave about 2575fps in the test barrels and always delivered excellent accuracy. </div></div>

Thanks. I emailed both Sierra and Hogden about the discrepancies.
Their accuracy load makes sense. My load of 41.0gr Varget and a 175gr SMK showed to be very accurate from the 18" barrel of my SASS.
 
Re: Variation in load data?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: pepperbelly</div><div class="ubbcode-body">
I have always been taught to go by the book and never exceed published load data. I know they change data over the years due to slight changes in powder, bullet design, etc.
Since the data Hogden has on their website would also be considered to be published the wide variance is worth being concerned about.

I found a very accurate load today. 41.0gr of Varget. That is inline with the Sierra data but much lower than the Hogden starting load. I was also taught to not load under a minimum published load. That is why I am concerned. </div></div>

Look dude

Rules are for the obedience of fools and the guidance of wise men
 
Re: Variation in load data?

Actually, the variation you've noted in the data by two different manufacturers makes a very strong argument for owning ont just one, but several reloading manuals. I buy every new manual that comes on the market, each and every year. I have for over 25 years now. When working with a new combination I'll go back and cross check several, just to se what sort of variations there is across the board, That tells me something about the combination, and just how touchy it may be in practice. I have QuickLoad, and use it extensively, but I wouldn't trade my manuals for it. I rely on a combination, for precisely the reasons that we've covered here so far.

Besides, each manual has its own little tidbits of information that you may not find anywhere else, and that's worth a lot. I have no idea precisely how many reloading manuals I have in ky library, but I'm sure it's near a hundred or so.
 
Re: Variation in load data?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Kevin Thomas</div><div class="ubbcode-body">Actually, the variation you've noted in the data by two different manufacturers makes a very strong argument for owning ont just one, but several reloading manuals. I buy every new manual that comes on the market, each and every year. I have for over 25 years now. When working with a new combination I'll go back and cross check several, just to se what sort of variations there is across the board, That tells me something about the combination, and just how touchy it may be in practice. I have QuickLoad, and use it extensively, but I wouldn't trade my manuals for it. I rely on a combination, for precisely the reasons that we've covered here so far.

Besides, each manual has its own little tidbits of information that you may not find anywhere else, and that's worth a lot. I have no idea precisely how many reloading manuals I have in ky library, but I'm sure it's near a hundred or so.
</div></div>

Kevin, one thing that really has me concerned is that the Sierra load data shows a much lower minimum charge than Hogden's online data. In fact Sierra's max load is less than Hogden's starting load. Hogden's data also covers a much smaller range.

I am really curious whether the brass makes this much of a difference. I am going to dig out some other manuals and see if I can find a spread like this.

I will be very interested to see what brass they use and what they tell me when they respond to my email. I have had several people tell me that they load a much higher charge than in the Sierra manual.
I have also had someone tell me the manual is a guide, but it is very very hard for me to ignore a published max charge- especially in favor of something on the 'net or from someone posting on a web forum.
 
Re: Variation in load data?

I was on another sight a while ago and a poster chimed in and stated that the whole process, which he stated he was part of was a very elaborate set of steps to determine published loads. The readers digest version was that after product testing by the manufacturer the data went through several other steps to include legal services "attorneys" before it was included in the manual. The specific data discussed was believed on the low side to reduce the chance of overcharging a case.
Therefore the max data may not really be the max. That being said read the above post about hot loads they may not be the ticket all the time.
 
Re: Variation in load data?

Sierra is well known for being super conservative. It's why I wouldn't use them if looking for a load. I would use the powder manufacturer's data. You are free to use whatever data you want as all will be safe as none of them want to be sued. That said if you might be shorting yourself on some performance.

Yes brass can make a difference but there are alot of people running 43grns of Varget with LC brass, which is probably has the least internal capacity of brass used.
 
Re: Variation in load data?

Pepperbelly,

Yes, it's fine with certain loads (being under the listed "start"), but not all. You'll note that this is most often found in the mid burning range powders, such as the Varget. Most of the powders in this range can tolerate a wide span of charge weights with no problem. The so-called "magnum" powders, such as 4350 or anything slower, is where you start to get into potential trouble areas with SEE or pressure excursions. These need high loading density, and definately shouldn't be started at loads below those shown.

As far as the loads in the Sierra manuals, I can assure you, they were indeed max loads for the firearm and components that were used. Despite the claims of some that there's a built in "fudge-factor," there isn't. That's not to say that the loads listed in there are maximum in your rifle, or that the listed loads are even safe in your gun; just that they were maximum loads in the combination that was used in developing the data. Like I said, a manual is just a report of loads tried, and results obtained/observed. Word to the wise here: Your mileage may vary.
 
Re: Variation in load data?

Rooster931,

I'd take anything said by the poster you mentioned with a very large chunk of salt from now on, unless he very specifically names who he was involved with as to how those loads are developed. He's either completely BS'ing you, or has no idea what he's talking about. There's no lawyers looking over or controlling the output of ballistics labs as far as what goes into the manuals.

Lawyers come later, after someone decides that you screwed up somewhere during the process.
 
Re: Variation in load data?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Kevin Thomas</div><div class="ubbcode-body">

As far as the loads in the Sierra manuals, I can assure you, they were indeed max loads for the firearm and components that were used.
</div></div>

I highly doubt that any combination or rifle and brass/primers with Varget and a 175 SMK was hitting pressure at 41.7grns.
 
Re: Variation in load data?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Kevin Thomas</div><div class="ubbcode-body">Twist rate actually plays a very minor role in pressure, usually well under one half of one percent, even in extreme examples. Throat length and leade angle on the other hand . . .. </div></div>

Just using the most extreme variable I could to make my point that any variation from the exact combination used in the data will result in different pressures. For that matter even exact duplication of components under unequal atmospheric conditions will produce different data. No intent of sarcasm.
 
Re: Variation in load data?

None taken, and point well made. Thing here is, there's so many variables that most shooters are completely unaware of, or never take into consideration. It'd scare most people to death to realize just how many variables go into these things. It'd also amaze them at just how well the industry in general does in keeping everything within some tolerable range of "different," so that those instances of "tolerance stack" don't create more problems than they do.
 
Re: Variation in load data?

What made me start looking at data was some marks on my case heads when using a load with 43.0gr of Varget and the 175gr SMK. It was a load I had from when I had a bolt rifle.
The marks looked like ejector swipes. I have since found that my rifle is notorious for chewing brass that way. But, they did look like signs of too much pressure.

When I look for pressure I also keep in mind an article I read years ago in Handloader magazine. They tested the usual pressure signs- flattened primers, etc. They placed a strain gauge on the barrel and started testing loads.
The scary part of the article was the fact that they exceeded pressure well before any of the signs we look for started showing.
I believe their recommendation was to use a chrono and not exceed the listed velocity. In their test they noted that velocity increased up to the point max pressure was obtained, then the velocity increase slowed and started falling even though powder charge increased and pressures rose dramatically. They did notice accuracy also went to crap when the pressure got too high, and best accuracy was obtained at a near max charge for that powder and load.

They had another very interesting article where they obtained overpressure with a too low charge of pistol powder in a revolver just by pointing the muzzle low before firing.
 
Re: Variation in load data?

Things spewing back into my face usually tell me I have my load a little too hot
wink.gif


seriously, pepperbelly, try moving on up slowly toward around 44.5 to 44.7 grains of Varget with that 175. I have found that to be a real sweet spot in several 308 rifles.
 
Re: Variation in load data?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: shoot4fun</div><div class="ubbcode-body">Things spewing back into my face usually tell me I have my load a little too hot
wink.gif


seriously, pepperbelly, try moving on up slowly toward around 44.5 to 44.7 grains of Varget with that 175. I have found that to be a real sweet spot in several 308 rifles.</div></div>

I will work up to those loads watching very closely for signs of pressure. Or at least I will after I shoot this load some more. It put 3 rounds in a small cloverleaf with the last 2 rounds into almost a single hole a half inch to the right. I was pissed about the group opening up until a friend said the wind had shifted directions during my shot string.
If this load is that accurate I will definitely be keeping it and work up a hotter load for longer distance later on.
 
Re: Variation in load data?


I received a reply from Sierra Bullets today I will post it here. It is as many here thought it might be.

"Good morning Jim,

I understand your concern. Our data is slightly conservative and I have seen various shooters using 41 to 44 grains of Varget with our 175 grain MatchKing with excellent success safely in bolt guns as well as gas guns.

There are no special considerations to using our MatchKings in your gun so I suggest starting with our data and working up through Hodgdons data because who knows their product better than the manufacturer but we all know that what works well in one gun may not react the same in another.

I like the 41.7 load you arrived at so if your gun likes it and you like it that is the load I’d use. - Rich "
 
Re: Variation in load data?

Two of my Rem 700's like 42.5 and 44.5 gr of varget with 178 bthp's. I've fired up to 46 gr but velocity and accuracy did not improve.
 
Re: Variation in load data?

My jug of Varget is dead nuts on per the Quickload library for pressure and velocity. I am not sure about load density.

If I put 308, 2.8", 175 gr SMK, 24", not touching lands, into QL,
For an output I get 105.5% filling ratio, 62.3 kpsi, 2714 fps.

The SAAMI registered pressure for 308 is 62kpsi, but I run it more like 68 kpsi with Hodgdon extreme powders.
So the problem for me with 308 Varget and 175 gr SMK, is that not enough powder will fit.
 
Re: Variation in load data?

As I said, this is why you want to use multiple dataa sources; so you can see just what sort of variation exists with certain combinations.

As for Rich . . . I'm the one who hired him.
 
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