seemingly vast differences in load data for .308?

[evtSmtx]

• I'm looking to develop an LR-308 load in .308 using varget and hornady 150 gr fmjbt #3037
• lyman 49 references #3031 and suggests a load range of 42.5 - 47.0(compressed)
  • hornady 9th ed says #3031
    • is the interlock sp bullet
    • uses the same load as #3037
• but hornady 9th ed suggests a load range of 35.9 - 49.9

so

• does this make sense to anyone
• does anyone have personal experience with this bullet & varget?

FWIW the .308 has an adjustable gas block

 

[macgrumpy]

Well first of all, I think you mistyped the max load from the Hornady manual, I'm looking at my copy of he 9th edition Hornady manual and I see a max load of 44.9gr.

Of course your next point will probably be that regardless, why is there such a difference between two manuals and, as I've told a lot of other people that have asked the same question, you have to pay attention to the details.

Each manual will specify how the load was developed and rarely will they use the same components or weapons to develop the powder charge recommendations. I have the 48th edition of Lyman's manual and it specifies that they used a Remington case, a Remington 9 1/2 primer, and a 24" universal receiver while Hornady says that they used a Hornady case, a Federal 210 primer, and a 22" barreled Winchester 70 model rifle. The different cases will have different volumes which will produce different pressures using the same amount of powder. The different primers will produce different burn patterns which will result in different pressures also. The longer barreled universal receiver used by Lyman will handle higher pressures and it will produce faster velocities than the shorter barreled model 70 used by Hornady. Take note also that Lyman shows that they get 2632 fps with 42.5gr of Varget (in the longer barrel) and Hornady indicates that they get 2600 fps with 42.6gr of Varget.

Checking for estimated max pressures using my QuickLoad internal ballistic software, Hornady uses a lighter max powder charge than Lyman for whatever reason, maybe they don't like the pressure curve that Varget has for the .308 Win cartridge but both manuals show a max powder charge weight that produces max pressure that is well under the SAAMI maximum recommendation. Since the bullets are made by Hornady, maybe Hornady knows something about the bullet's construction that Lyman doesn't, maybe Hornady doesn't think that the bullet is capable of being as accurate with powder charge weights heavier than 44.9gr of Varget. Maybe, since Hornady used a Winchester Model 70 rifle to develop their load information, they figured that 44.9gr of Varget produced the max pressure that they felt was reasonable for that rifle's action.

Regardless, I'll use the bullet manufacturers recommendation before I would someone else's. Oh, and by the way, try around 42.5gr of Varget with that bullet.

 

[Grumulkin]

• I'm looking to develop an LR-308 load in .308 using varget and hornady 150 gr fmjbt #3037
• lyman 49 references #3031 and suggests a load range of 42.5 - 47.0(compressed)
  • hornady 9th ed says #3031
    • is the interlock sp bullet
    • uses the same load as #3037
• but hornady 9th ed suggests a load range of 35.9 - 49.9

so

• does this make sense to anyone
• does anyone have personal experience with this bullet & varget?

It makes sense to me. Different components, testing conditions and testing systems will give different data. What I find a bit less logical are the manuals that list loads for identical powders such as Winchester 760 and H414 and come up with different data for each; that would probably be explained by different powder lots.

I have the 48th edition of Lyman's manual and it specifies that they used a Remington case, a Remington 9 1/2 primer, and a 24" universal receiver while Hornady says that they used a Hornady case, a Federal 210 primer, and a 22" barreled Winchester 70 model rifle. The different cases will have different volumes which will produce different pressures using the same amount of powder. The different primers will produce different burn patterns which will result in different pressures also. The longer barreled universal receiver used by Lyman will handle higher pressures and it will produce faster velocities than the shorter barreled model 70 used by Hornady. Take note also that Lyman shows that they get 2632 fps with 42.5gr of Varget (in the longer barrel) and Hornady indicates that they get 2600 fps with 42.6gr of Varget.

There is a flaw in that reasoning. The universal receiver may handle higher pressures but they're only going to publish a load within SAAMI specifications. Both the universal receiver and the Winchester model 70 rifles will handle maximum SAAMI loads so the fact that one testing system will handle more pressure than the other is irrelevant. Sure, the longer barrel will probably give higher velocities but that doesn't have to be because the pressure is higher.

Case volumes can make a difference in pressures and velocities but I think the differences are MUCH overrated. The above 5 shot group was shot with identical loads except the cases were all different.




.

 

[evtSmtx]

Well first of all, I think you mistyped the max load from the Hornady manual, I'm looking at my copy of he 9th edition Hornady manual and I see a max load of 44.9gr.

Of course your next point will probably be that regardless, why is there such a difference between two manuals and, as I've told a lot of other people that have asked the same question, you have to pay attention to the details.

Each manual will specify how the load was developed and rarely will they use the same components or weapons to develop the powder charge recommendations. I have the 48th edition of Lyman's manual and it specifies that they used a Remington case, a Remington 9 1/2 primer, and a 24" universal receiver while Hornady says that they used a Hornady case, a Federal 210 primer, and a 22" barreled Winchester 70 model rifle. The different cases will have different volumes which will produce different pressures using the same amount of powder. The different primers will produce different burn patterns which will result in different pressures also. The longer barreled universal receiver used by Lyman will handle higher pressures and it will produce faster velocities than the shorter barreled model 70 used by Hornady. Take note also that Lyman shows that they get 2632 fps with 42.5gr of Varget (in the longer barrel) and Hornady indicates that they get 2600 fps with 42.6gr of Varget.

Checking for estimated max pressures using my QuickLoad internal ballistic software, Hornady uses a lighter max powder charge than Lyman for whatever reason, maybe they don't like the pressure curve that Varget has for the .308 Win cartridge but both manuals show a max powder charge weight that produces max pressure that is well under the SAAMI maximum recommendation. Since the bullets are made by Hornady, maybe Hornady knows something about the bullet's construction that Lyman doesn't, maybe Hornady doesn't think that the bullet is capable of being as accurate with powder charge weights heavier than 44.9gr of Varget. Maybe, since Hornady used a Winchester Model 70 rifle to develop their load information, they figured that 44.9gr of Varget produced the max pressure that they felt was reasonable for that rifle's action.

Regardless, I'll use the bullet manufacturers recommendation before I would someone else's. Oh, and by the way, try around 42.5gr of Varget with that bullet.

yikes, ya the 49.9 was a typo. Thanks for your insight and quickload expertise. I'm planning, as you suggested, to follow hornady's guidance. I'm not new to reloading but I'm new to .308 and will be using mixed brass so - slow and steady workup.

 

[Bart B.]

For what it's worth, all the ammo companies as well as SAAMI people I've talked with about cartridge pressures, the weakest link in all of the stuff involved is the brass cartridge case. They start to extrude into unsupported areas at about 65K to 70K cup (80K t0 85K psi). The smart thing to do is get the max allowable peak pressure about 15K below those numbers. Which means the average peak pressure will be about 5K below that. This gives a wide safety margin should something cause an overpressure round to be fired because of something abnormal happening.

Even if someone uses the same piezo transducer pressure system on another rifle chambered with the same load, the peak pressure they get can be a few K psi different than the other got. And that same load in a SAAMI spec pressure system typically will show a different pressure.

Too many rubber rulers out there trying to measure the same thing. The numbers get stretched way to much to be 100% believable and reliable.

 

[evtSmtx]

It makes sense to me. Different components, testing conditions and testing systems will give different data. What I find a bit less logical are the manuals that list loads for identical powders such as Winchester 760 and H414 and come up with different data for each; that would probably be explained by different powder lots.



There is a flaw in that reasoning. The universal receiver may handle higher pressures but they're only going to publish a load within SAAMI specifications. Both the universal receiver and the Winchester model 70 rifles will handle maximum SAAMI loads so the fact that one testing system will handle more pressure than the other is irrelevant. Sure, the longer barrel will probably give higher velocities but that doesn't have to be because the pressure is higher.

Case volumes can make a difference in pressures and velocities but I think the differences are MUCH overrated. The above 5 shot group was shot with identical loads except the cases were all different.




.

Thanks for the info. It's a damned shame you shot such a fine group and still missed the quarter

 

[macgrumpy]

There is no flaw in my reasoning, the flaw is in your misunderstanding what I was trying to say. I mentioned that a universal receiver is stronger only as a description of the action not because I feel that it explains why there is a difference in powder charges, to assume I was saying that the receiver design somehow explained the charge difference requires one to ignore the rest of my post wherein I state that Hornady probably knows something about the bullet's construction that Lyman doesn't.

 

[Grumulkin]

The main things to know about bullet construction are:

1. How much does it weigh.
2. Is the bullet lead, monometal other than lead or is it jacketed lead core. Actually, for starting loads, I've never found it to matter if a bullet is gilding metal, copper or a copper jacketed lead bullet.

I think Lyman probably had that figured out.

 

[macgrumpy]

I thought that the idea of this forum was to help the OP with his question, not to spend time ridiculing the responses of people that actually tried to help, I guess that it's just another example of the helpful, courteous membership of the THR forum that I always hear about.

As I stated, my GUESS (which is pretty much what everybody else can provide because none of them have any factual information as to why these differences exist) is that Hornady knows their bullets best and has their own reasons for showing a lighter load than Lyman does and most likely it has to with what Hornady considers to the more accurate powder charge weights rather than just listing a max pressure and velocity load.

 

[Sunray]

"...why is there such a difference between two manuals..." Different day. Different rifle/universal receiver. Different powder lot. Different primer lot. Manuals are different but all are safe to use. Mind you, I think Lyman tends to use a real rifle vs a universal receiver. Not that it'd matter.
"...the bullet's construction..." Makes no difference at all. The only thing that matters is the weight and jacketed or cast. The brand of bullet doesn't matter either. In any case, just work up the load, paying attention to the OAL and you must FL resize for any semi-auto.
Don't worry about compressed loads either. Nothing to be concerned about.
I seem to recall the guys I sold real AR-10's to long ago used BlC2 and/or IMR4064. Been a very long time though.

 

[dh1633pm]

My LR-308 like loads about center of the reloading manual's lowest and highest charge amounts. Somewhere in the 2600 FPS range. I am sure you can work up a load. I used IMR4895 when Varget was hard to find and found an excellent load for both 150's and 168's. With a powder like Varget that everyone swears by, you should have a load in no time.

 

[kingmt]

The main difference is that it was done by two different people. It's just a story about what they did & what they found. Your spouse to use your own mind from there.

Bullet construction as in shape does have a bunch to do with pressure produced.

 

[evtSmtx]

The main difference is that it was done by two different people. It's just a story about what they did & what they found. Your spouse to use your own mind from there.

Bullet construction as in shape does have a bunch to do with pressure produced.

That's a little less than useful when trying to explain a 15% difference in max loads for similar bullet types but ok.

 

[kingmt]

Then you must not be understanding what I'm telling you. When you get load data from any source it isn't any law. It's good practice to fallow if you don't have any other information to go off from but basically it's just what they did & but what you have to do. I use published data to find a starting then start adjusting it up or down depending on what I want to do. It doesn't always achieve what I want it to do I'll abandon it & look for another powder that will. There is several times you wouldn't find my loads in any book that I know of. Other times I find published data to be exactly what I was looking for. Then there are a few powders I have the is no data at all for.

 

[Blue68f100]

From what I have noticed about Hornady's load data is they normally seat the bullet shorter than say Sierra. Hornady will have a 2.200" while Sierra will be 2.250" on 223R. This is one of the reason the loads are lower on Rifle. It's all about the details in how they ran their test. Test receiver vs rifle, OAL, Length of barrel impacts velocity....

 

[Bart B.]

Sierra develops load data for their bullets with a commercial rifle most of the time and they list the primary rifle details. Their best hunting and match bullet types and weight recommend have been tested in several rifles.

I've used Sierra's hunting bullet suggestion with excellent results first time around.

 

[jmr40]

Always trust the most recent data. I prefer to use hodgdons website. http://www.hodgdonreloading.com/

Over time powder specs change. IMR3031 produced today is very likely somewhat different than what was produced 20 years ago. Also bullet construction changes and matters more than it used to. Years ago a 150 gr .308 bullet from all manufcturers was pretty much all the same. Today different bullet profiles, different construction etc. can mean small differences in load data, especially as you approach max loads.

 

[BigBore44]

Sierra develops load data for their bullets with a commercial rifle most of the time and they list the primary rifle details. Their best hunting and match bullet types and weight recommend have been tested in several rifles.

I've used Sierra's hunting bullet suggestion with excellent results first time around.

Sorry Bart. But I've been to Sierra's plant in Sedalia Mo, their loading room, and to their underground test range several times. They're also literally next door to Starline Brass. They do not use rifles. They have different actions with very thick short barrels. And they also don't use any special powders. They use whatever they can buy. I saw several different 8lb jugs and even single pound canisters laying around. That REALLY blew me away. I figured they used specific powders. They said it doesn't matter what powder they use. They don't care about velocity. They care about consistency.

Now, having said that, I'm a very big fan of Sierra bullets and Starline brass. Sierras are some of the absolute best you can buy. And no one I've ever found questions that Starline is the best. If you get the chance to go tour both plants, you should. They're free tours. Ask all the questions you want. They are very pleasant people and will try to answer all of them.

 

[Bart B.]

Sorry Bart. But I've been to Sierra's plant in Sedalia Mo, their loading room, and to their underground test range several times. They're also literally next door to Starline Brass. They do not use rifles. They have different actions with very thick short barrels.

I know they don't test bullet lots for accuracy in rifles; they've used rail guns for decades for quality control. Such devices have fewer variables than hand held rifles.

Sierra's reloading data is developed with rifles; it's described for each cartridge listed in their reloading manuals and Infinity software. Some are tested in several rifles and the load giving best accuracy across them is recommended in print. As are the best hunting loads

I've been to their Sedalia plant a couple times; several times in their California plant.

 

[BigBore44]

Ok I see what you're saying. Can't speak to them using actual rifles, but it is stated in their manuals. Which begs the question "Why?". As loaders, we all know that every rifle is different. Some rifles are most consistent with lower end loads. Some shoot best near or at max. And just like the advice we give, start low and work up. Knowing what a particular rifle likes doesn't really mean anything. For example, my 1894 44 mag shoots a Sierra 240gr JHC very well with a below minimum charge of H110 for rifles (22.5 gr). But the next 1894 I get might not shoot that load worth a darn.

 

[Bart B.]

As loaders, we all know that every rifle is different.

They're not as different as most people think.

Best example is the World Long Range & Palma Championships. Everyone has to shoot the same ammo. That's based on the century old Great Britain philosophy that it creates a level playing field. It's amazing how accurate some arsenals can make ammo that tests sub MOA at 1000 yards across all sorts of barrels' chamber, bore and groove dimensions. The ammo I helped work up a load for as the bullet was new and never sold at retail at the time. Several thousand rounds were loaded on two Dillon 1050 progressives. During one run, a hand full were taken from the second machine then all 20 tested from a Win 70 based Palma rifle at 600 yards; all inside 2.8 inches. Across a few dozen rifles from around the world the ammo was first shot in at their first match, their owners said they shot about 1/2 MOA at 600 yards, 2/3 MOA at 800 and 3/4 MOA at 1000. Same at the world championships a couple months later. That's as tested, which is about 1/3 what they shoot off the shoulder in prone.

Few people reload ammo as good as what commercial match ammo will do and it shoots very well across most rifles in good condition.

Tis my opinion the basis behind this claim is the way they're tested with any load. The first or first two few-shot groups shots represent the accuracy/precision that load has. However, if it was shot in several rifles of equal quality a few dozen times, the largest groups for each rifle would be pretty close to the same size. Most people don't want to believe that the odds of one or two few-shot groups representing the load or rifle's accuracy/precision has less than about 40% credibility. Statistics be damned; I know that's a popular way to think about testing rifles and ammo for whatever. The popular belief is "What I do is good enough for me."

 

[Robert101]

I have to agree with Mcgrummpy, I'd try the 42.5 grains of Varget with that 150 btfmj. I shoot a lot of them an find that they tend to fly straighter with a lighter charge. I'm too cheap to spend twice as much on great bullets (like Berger, Sierra Match), so I shoot the cheap stuff mostly in my LR308.

 

[Bart B.]

46 grains of Varget under Sierra's 155-gr. match bullet was a popular load with Palma Team members. It shot as good as 45.5 grains of IMR4895.