Question on burn rates

[conan32120]

Could it be said that slower burn rate powders work best with heavier bullets and faster powders work with lighter bullets with barrel lengths being the same? IE should cfe223 (111 on hodgden chart) perform better than IMR 4895 (96) for a 180gr .308 bullet? Reason for question is my 10 twist savage with a 20" barrel is having issues closing groups with both 180 and 150gr pills. Varget doing well with 168s but I'm having trouble expanding it's bullet weight range.

 

[Walkalong]

Kind of sort of. The heavies need a slower powder to maximize velocity

 

[Laphroaig]

Maybe I'm reading between the lines too much, but a168 gr. 30 cal is generally a match bullet where 180 and 150's could be hunting bullets that just don't have the same accuracy potential.

Any of the powders that you listed are suitable, you just might have to find the right combination. Or maybe something else will be magic in your rifle. Keep trying. All bullets aren't the same.

 

[conan32120]

I do a knowledge that the 150 and 180's are not as accurate as match 168's but I'm having troubles getting less than 3moa with them

 

[AJC1]

I do a knowledge that the 150 and 180's are not as accurate as match 168's but I'm having troubles getting less than 3moa with them

Faster powders have proved to be accurate across the board. Imr4895 has made good groups in 150s, I've used speer 150s with 44.4 grains to get sub moa 10 shot groups. I've also seen, but not built myself yet that same powder shoot cast boolits in the 160-200 grain range at or sub moa in 308. Slower powders give more velosity with the heavies which is important for hunting terminal ballistics. With 150s I've also got sub moa 10 shot groups with 44.8 grains of n135. If small groups is your go try a good extruded powder.... the best ball powder I've shot is TAC

 

[GeoDudeFlorida]

Could it be said that slower burn rate powders work best with heavier bullets and faster powders work with lighter bullets with barrel lengths being the same? IE should cfe223 (111 on hodgden chart) perform better than IMR 4895 (96) for a 180gr .308 bullet? Reason for question is my 10 twist savage with a 20" barrel is having issues closing groups with both 180 and 150gr pills. Varget doing well with 168s but I'm having trouble expanding it's bullet weight range.

Be careful about reading too much into “burn rate” charts. There is no standard for testing burn rates with nitrocellulose- or nitroglycerin-based powders.
You can use the charts as a general guide - a very loose guide - to compare one manufacturer’s powders to each other but even then you’re pushing the credulity of the charts to the limit.
Is your rifle off-the-shelf, custom barrel, custom built, or Frankenrifled from pieces-parts? What profile is the barrel and how is it cut? What’s the throat lead/jump measure?

 

[Howa 9700]

That was going to be my next question. What objective measure is used to determine burn rates? Apparently there is none. I can lay my hands on 4 or 5 burn charts, and while there are a few groups found in the same ball park, the players are assigned different positions.

More helpful is the way some published load data is presented. Some list loads from fast to slow burn speeds........or highest to lowest velocity.

 

[AJC1]

That was going to be my next question. What objective measure is used to determine burn rates? Apparently there is none. I can lay my hands on 4 or 5 burn charts, and while there are a few groups found in the same ball park, the players are assigned different positions.

More helpful is the way some published load data is presented. Some list loads from fast to slow burn speeds........or highest to lowest velocity.

I consider burn rate based on volume of powder in the same load table. I've been told that burn rate is case dependant but I've not seen any change in position in the rounds I load. I am 100% confident in a powder companies ranking of its own powders. Powders compared to other companies gets real fuzzy real fast. Shooters World heavy pistol acts nothing like #9, but does download significantly better despite the companies claim that they are "simular".

 

[Walkalong]

II've been told that burn rate is case dependant but I've not seen any change in position in the rounds I load. I am 100% confident in a powder companies ranking of its own powders.

It does make a difference what caliber, it just isn’t definable, nor just any two different ones.

Yes, the powder company burn rate charts are consistent for that one “closed bomb” test, but they can still move up or down with the application.

Yep, I take the charts with multiple companies powders on it with a grain of salt.

 

[AJC1]

It does make a difference what caliber, it just isn’t definable, nor just any two different ones.

Yes, the powder company burn rate charts are consistent for that one “closed bomb” test, but they can still move up or down with the application.

Yep, I take the charts with multiple companies powders on it with a grain of sasalt.

Any faith that hogden distributes just about everything they will clean up the charts. Alliant is the only one they don't controll right???? Norma is completely absent and shooters world is just another company repackaged...

 

[jmr40]

Yes, but. With a 308 you should be able to get good results with the same powder with bullets 150-180 gr. I've gotten good accuracy and velocity with bullets in that range with all of the common 308 powders. Varget, RE15, IMR 4064 and H4895. Anymore I just use Varget, if available. 4064 is my 2nd choice and RE15 my 3rd. I can get virtually the same accuracy and velocity with any of those. I choose Varget because it is more stable across a wider range of temps. 4064 seems to always be available and at good prices. .

It is when you start loading bullets lighter than about 150 gr or heavier than 180 gr that you will start seeing significant gains in performance with a different powder.

SOME rifles are more picky about the loads. The issue may be with your rifle, not the powder. Your rifle might just like the 165/168 gr weight bullets better. Or it might like a different brand of 150's and 180's.

 

[ArchAngelCD]

The information missing here is:
Which bullets are you using?
Which brass are you using, is it the same for all tests?
What is the COAL?

All these factors will contribute to accuracy of lack of accuracy.

Pick 1 powder and 1 bullets to work up. Do a standard powder charge work up. Find the most accurate node. Then you can play with the OAL and see if you can improve accuracy. Unfortunately there is no easy answer to your question. You will need to put the work in to find a good hunting load in YOUR rifle.

 

[Slamfire]

Pretty much back in the day for NRA HIghpower, the 308 Win in a bolt gun, IMR 3031/IMR 4895 was commonly used from 125 grain (standing) to 168 grain bullets. From 168 to 175 grain it was IMR 4895/4064. The most common load with a 168 was with IMR 4895. Toss a coin with 175 grain bullets. From 175 to 190 grain bullets most were using IMR 4064, a few IMR 4350. The trouble with using IMR 4350 with a 190 grain SMK was finding a case thin enough to get 47.0 grains in. Thick walled military cases would not take enough powder and the velocity was low.

 

[NMexJim]

The information missing here is:
Which bullets are you using?
Which brass are you using, is it the same for all tests?
What is the COAL?

All these factors will contribute to accuracy of lack of accuracy.

Pick 1 powder and 1 bullets to work up. Do a standard powder charge work up. Find the most accurate node. Then you can play with the OAL and see if you can improve accuracy. Unfortunately there is no easy answer to your question. You will need to put the work in to find a good hunting load in YOUR rifle.

Since OP mentioned CFE223 and IMR4895 re burn rates, I would add that some powder density general knowledge/discussion might be handy. I’ll attach this:

Choosing a Powder for a New Cartridge

www.hodgdonreloading.com

 

[Ru4real]

Generally, an extruded, single base powder that fills the case to the case shoulder or base of the bullet does best In my experienc.e.

Best being tightest and most consistent groups combined with low ES and STDDEV. Examples, Retumbo in 7mm Rem Mag or Varget in 223.

The single based powder is also more stable over time. Think loads today, shooting 40 years from now. Stuff happens.

Exceptions? For sure. And that’s where testing by you is key. Set your standard with single base full case, and then beat it with a double base or triple base, if you can.

 

[ArchAngelCD]

Since OP mentioned CFE223 and IMR4895 re burn rates, I would add that some powder density general knowledge/discussion might be handy. I’ll attach this:

Choosing a Powder for a New Cartridge

www.hodgdonreloading.com

That still doesn't help us help the OP. Without knowing what he's loading we can't help him figure out why accuracy is suffering in a cartridge which is usually easy to load for accuracy. This is especially true with the powders he is using. If you can't find an accurate load using IMR4895, H4895 and IMR4064 with a quality bullet something is very wrong.

 

[AJC1]

That still doesn't help us help the OP. Without knowing what he's loading we can't help him figure out why accuracy is suffering in a cartridge which is usually easy to load for accuracy. This is especially true with the powders he is using. If you can't find an accurate load using IMR4895, H4895 and IMR4064 with a quality bullet something is very wrong.

It was not clearly stated what bullets were dealing with.... behind barrels, bullets are the second most important and it bears a closer examination.

 

[GeoDudeFlorida]

It was not clearly stated what bullets were dealing with.... behind barrels, bullets are the second most important and it bears a closer examination.

For that matter we also still don’t know what kind or profile barrel he’s using. Before bullets and way ahead of powders, the barrel and chamber are THE most important factor in accuracy.

 

[AJC1]

For that matter we also still don’t know what kind or profile barrel he’s using. Before bullets and way ahead of powders, the barrel and chamber are THE most important factor in accuracy.

I agree but likely that is the one fixed portion of the problem. I had advised him previously to run 155s because Palma bullets are normally tighter tolerance. A good answer does require key pieces of information and to much almost doesn't exist.

 

[GeoDudeFlorida]

I agree but likely that is the one fixed portion of the problem. I had advised him previously to run 155s because Palma bullets are normally tighter tolerance. A good answer does require key pieces of information and to much almost doesn't exist.

Yup. He told me it’s second hand which is why I wonder about the barrel. If it’s factory, even the light thin whippy stock barrel ought to put three holes almost touching at 100yds. So did the previous owner Billy-Bob Bo Bedazzled do some redneck engineering magic on the thing?

 

[AJC1]

Yup. He told me it’s second hand which is why I wonder about the barrel. If it’s factory, even the light thin whippy stock barrel ought to put three holes almost touching at 100yds. So did the previous owner Billy-Bob Bo Bedazzled do some redneck engineering magic on the thing?

My dad had a bad time with the factory 308 barrel and my target 223 withb30" shilen rifle was born. I still have the original barrel floating around his house with less than 500 rounds down the tube.

 

[ArchAngelCD]

For that matter we also still don’t know what kind or profile barrel he’s using. Before bullets and way ahead of powders, the barrel and chamber are THE most important factor in accuracy.

Completely true but since the OP said the 168gr match bullets are showing accuracy I wasn't worried about the barrel. Of course we are all going by very little info and can't look at or touch the gun. I'm sure we all agree we need more info.

 

[GeoDudeFlorida]

Completely true but since the OP said the 168gr match bullets are showing accuracy I wasn't worried about the barrel. Of course we are all going by very little info and can't look at or touch the gun. I'm sure we all agree we need more info.

Absolutely!
Also true is, no matter how great a powder is for Load A, that doesn’t mean much when it comes to Load B, C, etc et ad infinitum. Me personally I have never had the life altering experience most get from Varget. That doesn’t make it “bad” it’s just not magical in my rifles. Maybe @conan32120 needs to try 4064 or 4895 Rel12 or… there’s lots of good powder for .308Win

There’s also a reason nobody’s ever heard of IMR 1185 and why BL-C(2) is a bad choice for .303Brit but BL-C (WC 846) was made for that cartridge almost exclusively. Sometimes a good choice just doesn’t translate to all options.

 

[Howa 9700]

That still doesn't help us help the OP. Without knowing what he's loading we can't help him figure out why accuracy is suffering in a cartridge which is usually easy to load for accuracy. This is especially true with the powders he is using. If you can't find an accurate load using IMR4895, H4895 and IMR4064 with a quality bullet something is very wrong.

The statement in the Hodgdon link may be the only place I've seen that about full cases.....at least from Hodgdon or in most other manuals, but that has proven to be true for me. Enough so it has become my goal for all rifle loads and it appears the same thing exists for the 9mm pistol loads as well. And even in shotguns, they no longer stress seating pressure of 30 pounds or so as was once done, but the wad in a shotgun shell is seated firmly on top of the powder. My old Texan press even came with a pressure gauge you could use to measure the seating pressure.

The most likely reason I can come up with is by eliminating air space in the case and lightly compressing the powder, the ignition and burn of powder is always consistent.

That being the case, the are some powders, like IMR4064 where the max load is near or always compressed. That it often delivers good performance may be no coincidence.

 

[AJC1]

The statement in the Hodgdon link may be the only place I've seen that about full cases.....at least from Hodgdon or in most other manuals, but that has proven to be true for me. Enough so it has become my goal for all rifle loads and it appears the same thing exists for the 9mm pistol loads as well. And even in shotguns, they no longer stress seating pressure of 30 pounds or so as was once done, but the wad in a shotgun shell is seated firmly on top of the powder. My old Texan press even came with a pressure gauge you could use to measure the seating pressure.

The most likely reason I can come up with is by eliminating air space in the case and lightly compressing the powder, the ignition and burn of powder is always consistent.

That being the case, the are some powders, like IMR4064 where the max load is near or always compressed. That it often delivers good performance may be no coincidence.

My dad always talked about case fill around the bench for good consistency.... I'm sold on the idea, but also on the form factor. When world records, king of the 2 or 3 mile or any national level matches start being won with ball powder I'll take heed. It's coming some day but I have yet to see it. I'm also sure a funny car is being built with an electronic package over methanol.