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Conflicting reloading data

Helidriver

Helidriver

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Dec 6, 2009
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Surprise, AZ
I'm sure someone has seen this before.

My favorite load for my 308 is 41.4gr of Varget pushing 175 SMKs.

Recently I came across a Hodgdon reloading manual and it's got very different data than the Sierra manual. Sierra lists the 175SMK with Varget as having a max loading of 41.7gr. The Hodgdon manual lists the same combo having a max loading of 45.0gr. Hodgdon also says it's a compressed load. That's a big difference. How could the 2 companies be that far apart?

I would like to experiment with this load a little but I don't know what data to believe.
 
Re: Conflicting reloading data

"<span style="font-style: italic">How could the 2 companies be that far apart?"</span>

Easy; they used different rifles. Your's is different from either of their's so you can't willy-nilly presume either book will match your rifle's needs. THE rule is, "Start low, only work up to (book) max unless you encounter excess pressure signs earlier." By that ONE rule, correctly applied, it won't matter which book you follow. Ignore that rule and you can't folow any book safely.

 
Re: Conflicting reloading data

I understand that however the difference is to large for me to believe that it's the test rifles. Loading light on Hodgdon's manual places you over the max listed in Sierra's manual. If I just started reloading and all I had was the Hodgdon manual I would start my loads around 41.5 to 42.0. If Hodgdon says the max load is 45.0 I think that's well within a safe margin by their numbers however it's right at the max for Sierra.

As far as I know the limiting factor the companies use is chamber pressure which is calculated mathematically. Not based off of pressure signs. Freebore length, chamber dimensions ect all play a part but that big of a spread is surprising to me.
 
Re: Conflicting reloading data

I hate using the line that Sierra is conservative because it's not a logical answer but most of the time you will find that Sierra's max load is below the powder manufacturers max load.

Along with chamber and bore, brass play's a lot into pressure.
 
Re: Conflicting reloading data

If you want to experiment, follow the earlier advice to work your way up. I've seen significant differences in max loads in different books and I've seen significant differences in what various rifles are willing to put up with. I'm running a .270 load in three rifles that only one book says is ok, but all I'm seeing are some flattened primers but no stiff bolts or other issues, and I'm not convinced primers tell the whole story. Those loads really work for those rifles.

With regard to your load, I'm running 45.0 grains of Varget under 175 SMKs in two rifles with good performance right now, and I've tried that load in a third rifle, with no pressure signs of any kinds. Whether on not the load is compressed depends on how deeply I seat the bullet.
 
Re: Conflicting reloading data

Run a ladder with your "favorite load" and increase .3 grain at a time and see if you come up with a better node, or if your favorite load is actually the best. JMHO
 
Re: Conflicting reloading data

As a side observation: most LR shooters tend to endup in the 45.0 gr range with Varget and 175 SMKs. Thus, this fits the Hogdon book and disagrees with the Sierra group.

Start low, and work up slowly until you see pressure signs.
 
Re: Conflicting reloading data

Agree. 41.7 is really light. When I was working up loads I believe 41.5 only chrono'd in the mid to low 2400s. Lyman has a max of 45.2 and while Speer doesn't have a 175 listed they do have 44 and 46 for 168 and 180 respectively which are more in line with Hodgdon.
 
Re: Conflicting reloading data

Looking at Quickload, and the Varget model in Quickload library is usually within 1%, the max load per SAAMI 60kpsi would be 44.4 gr, and the real max practical load [with temperature, component, and reloading process safety margin to assure long brass life with the large Boxer primer pocket in that case head] would be 46 gr at 67kpsi.

If one ran a test; Take different brands of rifles, different hand loaders, different batches of powder, different brands of brass, different brands dies, different brands of primers, different ranges, different shooters, and different temperatures. Work up to the threshold of long brass life, and then back off 4% powder charge. Both processes should be within 1% or 2% of the 46 gr that Quickload calculated.
How did Sierra and Hodgdon get 8% apart?
They were not doing the same test the same way with the same benchmarks and the same safety margin.
 
Re: Conflicting reloading data

This is a very interesting thread for me. I have been playing with Quickload for a while now trying to come up with a load for my 16 inch REPR.

I have been trying to get a load that will have the correct barrel time to match an accuracy node, and it had been pretty interesting. I first learned that I needed to determine the H2O capacity of my brass. The 56 grain default was a lower than 57.7 that I came up. (I hope I am doing this right)

I then realized that my barrel is actually 16.1 inches, so all the calculations from what Quickload was producing and the node that I was looking for were all a little off.

Anyway, back on topic: There are two accuracy nodes that I am trying to reach using 178 AMAXs and either Varget or RL-15. I am also trying 175 SMKs, but this rifle seems to prefer the AMAXs. The slowest nodes are easily attainable with pressures in the mid 50K PSI range. With the short barrel, these loads are leaving the barrel around 2420 FPS. If I want to get some more muzzle velocity, I have to powder up to 46.5gr of Varget or 47.2gr of RL-15 to hit the next node. Quickload says the Varget load should have 63,761 PSI and send the bullet at 2512 fps. The Rl-15 load will be at 64,738 PSI and be traveling at 2561 FPS.

I am interested in Clark's comment about "real max practical load." I have shot a good amount of 46gr Rl-15 loads when using the data based on a 16 inch barrel, but have not had the cohones to go any higher than that. Those loads did not show excessive pressure, cycled fine and were fairly accurate.

Does any body think I might be able to go a little hotter to try to get to the next node?

Thanks,

Shaky
 
Re: Conflicting reloading data

Ok help me out here. I'm not real experienced with reloading. What does node mean?
 
Re: Conflicting reloading data

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Dirty Rod</div><div class="ubbcode-body">Agree. 41.7 is really light. When I was working up loads I believe 41.5 only chrono'd in the mid to low 2400s. Lyman has a max of 45.2 and while Speer doesn't have a 175 listed they do have 44 and 46 for 168 and 180 respectively which are more in line with Hodgdon. </div></div> I think you mean the other way around: 44 grs for the 180 and 46 grs for the 168.
 
Re: Conflicting reloading data

A node refers to a powder charge that results in the bullet exiting the barrel at a favorable instant. Typically when the muzzle is flexed upward and paused before it bends back down. Based on harmonics. A good node will give you good groups even with a wide powder charge variation. There is usually a good node near the max charge and another good node at a lower charge with intervening powder charges that cause bullets to "scatter" more. There are probably more nodes as you drop the charges, but why would you want your bullets going so slow?
 
Re: Conflicting reloading data

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: targaflorio</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Dirty Rod</div><div class="ubbcode-body">Agree. 41.7 is really light. When I was working up loads I believe 41.5 only chrono'd in the mid to low 2400s. Lyman has a max of 45.2 and while Speer doesn't have a 175 listed they do have 44 and 46 for 168 and 180 respectively which are more in line with Hodgdon. </div></div> I think you mean the other way around: 44 grs for the 180 and 46 grs for the 168. </div></div>

Thank you. I stand corrected.
 
Re: Conflicting reloading data

Agreed that all of my manuals and the manufacturers have quite a variation in recommended loads. Sometimes they barely overlap at all. Hornday's manual always seems low.

I always look at others recommended loads, sanity check as many references as possible then the usual - start low and work up...
 
Re: Conflicting reloading data

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Helidriver</div><div class="ubbcode-body">Ok help me out here. I'm not real experienced with reloading. What does node mean? </div></div>a node is the time in milliseconds when the distortion waves that travel up and down the barrel are closest to the action, and therefore furthest from the muzzle. You can read more here
http://www.the-long-family.com/optimal%20barrel%20time.htm

 
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