Powder's effect on accuracy

[Big_Sloppy75]

I have a really odd issue that I have found. I have a Remington 700 VTR in a .308. I have had accuracy troubles in any load, hand or factory, that is not using CFE .223 is there any reason for this? Can a rifle prefer a specific powder? Or is this all coincidence? All opinions welcome, thanks for reading!

 

[Klint Beastwood]

Yes, slow burning powers often like heavier bullets. Fast burning lighter bullets. However plenty of people have found good precision with random combos. In reloading, everything can be relevant to obtain maximum efficientcy in precision, from the brass prep to the powder to the bullet and seating relevant to the gun. Hard to narrow your issue down to just if it’s specificly the powder.

 

[LoonWulf]

some guns are odd like that. Lets first define accuracy trouble, are we talking unusually large groups? do they string? how large are they? If your seeing a bunch of 1-1.5" groups and suddenly cfe223 provides groups in the .75 or smaller range thats not particularly unusual.

And again some guns are just picky. What ive usually found tho, is that guns that are unusually picky often have something weird going on. loose parts, uneven crown, weird chamber etc.

And like KB said, hard to say for sure its a powder issue unless everything else was exactly the same for each load.

 

[Reloadron]

Powder's effect on accuracy

Oh yes, very much so. The Holy Grail for each rifle is finding that right combination of powder, primer and bullet along with trim length and bullet seating depth and...and...and in the never ending quest for repeatable results for a given load. Generally, as Klint Beastwood mentions slower bullets are associated with the slower powders within a caliber. Then certain powders with for example gas guns verse bolt guns. If there is an ideal .308 Winchester load for all my .308 Winchester guns I have yet to find it. Gas guns we seek certain pressure curves and not just looking at peak pressure but the whole pressure curve. Especially the area under the curve. So yes, powders weigh (no pun) very heavily into the accuracy game.

Also bullet weights play into the game. You likely have a 1:12 twist rate, have you tried different bullet weights and types?

Ron

 

[Big_Sloppy75]

Coincidentally enough, my groups are about 1.5 with any load and with the 2 CFE 223 loads I've developed they are around .5-.75. Thanks for the info guys! Also my twist rate is 1:8 and I have tried different weights. Heavier generally does better

 

[Reloadron]

Coincidentally enough, my groups are about 1.5 with any load and with the 2 CFE 223 loads I've developed they are around .5-.75. Thanks for the info guys! Also my twist rate is 1:8 and I have tried different weights. Heavier generally does better

Just out of curiosity was this rifle re-barreled? I ask because that is a really fast twist for a 308 Winchester chambering. Remington MODEL 700 VTR SPECIFICATIONS reflect a RH Twist of 1:10 which would be typical. They do show a 1:8 but only for the 260 Remington chambering.

Ron

 

[Walkalong]

have a Remington 700 VTR in a .308.

my groups are about 1.5 with any load and with the 2 CFE 223 loads I've developed they are around .5-.75

Have you tried IMR-4064, IMR-4895, or RL-15?

 

[Varminterror]

A good powder choice for the charge weight, cartridge, and bullet weight will be forgiving, meaning production of consistent, precise ammo is much easier than with a lesser fit powder.

In operational excellence, there is a paradigm adage in which, "it's really hard to win, but it's really easy to lose." This describes effectively a life of diminishing returns where even slightly improving processes which have been repeatedly improved time and time again becomes harder and harder, whereas it's incredibly simple for low level errors to have huge impacts in the form of production or efficiency losses.

WTH am I talking about???

THAT paradigm is what I consider when I do load development in comparing powders. When I do load development, I'm pressing on my Forster Co-Ax, all hand measured loads, just a handful to a dozen of each charge weight, with extreme attention to detail to have every bit of the loading process be extremely consistent. Annealed brass, trimmed, turned, weight sorted brass, primers, and bullets, hand weighed and confirmed charges... So it follows almost ANY ammo I produce in this manner should be pretty consistent...

So now let's move to volume production. I'm running big batches of brass, not sorted, and throwing charges either with the automatic dispenser or the powder drop, and cranking through the turret or the progressive press in batches of a few hundred rounds, or thousands, at a time... Lots of opportunity for variability...

Similarly, take that same load from an 85F afternoon of load development to a cold, damp morning at 20F in the deer stand. What happens to your 300yrd point of impact? What happens to your group size?

A proper combination of bullet weight, cartridge, powder charge weight, and powder selection can often forgive +/-0.3grn of powder measurement errors, let alone extreme variations of internal case volume. It'll also remain consistent even despite temperature changes - the POI will shift, but the groups will stay tight.

Lots and lots of powder choices will produce precise ammo if all of the quality control measures are at their peak, far fewer powders will produce incredibly consistent results in specific cartridges when normal variability comes into play.

 

[db_tanker]

My 308 really loves AA2520 as far as spherical goes. IMR 4895 for stick. The 2520 worked best with 168 and 175's. The 4895 with 147-155 gr. bullets.
This is where the fun part of reloading comes in. And it can be kind of expensive as well...you have to try out different powders and different bullets...
My experience is that you can have a rifle that likes a specific recipe however most rifles can shoot a good accurate combo with any powder...just depends on what levels of accuracy you want or need.

Klint there said it best...you can eventually find a combo that will work with what you have you just have to juggle all the pieces...what brass...neck size or FL size...primer...annealing the brass...finally powder and bullet...powder charge...seating height on the bullet (you have some wiggle room there...you can cast your chamber and get a handle on that) some rifles like it at the ragged edge of the max load...some don't....all it means is range time.

Hope this helps a bit?

 

[Art Eatman]

My guess is that in some manner, the different burning characteristics and pressure curves of different powders somehow affect the harmonics of a barrel's vibration. But, purely a guess.

 

[Big_Sloppy75]

You are right, it is a 1:10. The original barrel. I have only used BLC-2, CFE 223, and Varget. I haven't thought about shooting in different conditions either, kind of a no duh I guess

 

[Reloadron]

You are right, it is a 1:10. The original barrel. I have only used BLC-2, CFE 223, and Varget

Ah OK, then I would suggest you expand your horizons a little and work with some of the mentioned powders like IMR 4895, IMR 4064, AA 2495 and RL 15 just as a few to try. Also as the pocketbook allows try several different bullets including, for target, the Sierra Match King family and the Speer Gold Match family. Try and make only one change at a time meaning work a powder only or bullet only.

Ron

 

[boom boom]

A chronograph will help, even a relatively cheap one. A powder-bullet-brass-primer combo generating large variances in velocity between each shot is generally not helpful for very good accuracy.

 

[LoonWulf]

Ive had relatively poor luck with both blc2 and varget, in every cal ive tried them in, but other guys do great with them. Couple other questions, how close to max are you pushing? and what is your load work up procedures? Ive generally read most folks get better accuracy a few grains to 1/2 grain low on book max with both blc and varget, you maybe out of their preferred range if your up near the top of the load data.

Personally I think id try a few more powders and see where your at, I like Walkalongs suggestions for the .308
I shoot cfe223 almost exclusively in my .223, to not overbore.308 fam size cartridges.
My "do all" is imr-4895. havent found any rifle rounds that didnt shoot OK with 4895, besides some really small cases.

Again tho, CFE223 is a very good powder for velocity (im not aware of how temp sensitive it is), and generally very available. If your getting good accuracy. You may just wanna buy and 8lb keg and stick with it. Try different seating depths, smaller weight increments and different projectiles, to optimize your loads. Having one powder isnt really a bad thing when you can get it as easily as cfe223.

 

[Reloadron]

Couple other questions, how close to max are you pushing? and what is your load work up procedures?

How close to a maximum load do I load them? That really depends on the cartridge and the rifle. Using .308 Winchester as an example I load for at least 3 rifles, an AR10, M1A and my custom Remington 700 BDL bolt gun. Also "how close to a maximum" can depend on the manual you are working from. Hornady 9th Edition loading .308 Winchester under a 168 grain BTHP using IMR 4895 the Maximum Load is 43.3 grains. Speer #12 is 44.0 grains under a 168 grain BTHP. Hornady Service Rifle Loading come in at 41.4 grains of IMR 4895 under the same 168 grain BTHP. Loading for my service rifles I like 40.5 grains of IMR 4895 under a 168 grain HPBT. That seems to shoot well in both of my gas guns. I also never had much luck with ball or flake powders in a 308 gas gun or for that matter a 30-06 gas gun. What it comes down to is starting low with a powder charge and working up on a particular rifle observing your spent cartridges as you work up. While there is no great need to weigh cases you do want to use cases from the same lot and manufacturer. That also holds true for your primers. The idea is uniformity. When starting out I wouldn't worry much about seating depth and "chasing the lands" but rather work from the book. The load which great for me may not fare well in your rifle(s).

Just My Take....
Ron

 

[BrocLuno]

Rifle want one pawder - sure. Think about a barrel as a musical instrument tube. Strike it with one mallet and just the right power and it'll ring true. Do it with another mallet too hard, and it'll ring, but very differently.

So the ringing analogy is about the the what the barrel is doing just as the bullet leaves the muzzle ... If it's ringing "true" the bullet will leave about the same, so accuracy is good. If the barrel is off "pitch" the bullet will leave slightly differently and the impact point will shift.

So with powders there is a pressure curve. The shape of that curve is a contributor to barrel harmonics. Apparantly CFE223 has the pressure curve that your barrel likes. Easy peasy, just start playing with powders with similar burn rates and see what happens...

 

[bme27]

I have been following this thread as I am a recently new reloader, and I am curious as to why everyone is recommending the OP try different powders. He stated that CFE223 gets him .5-.75 MOA consistently. Did he want to shoot tighter groups then that? If not, why have him shoot more powders when one already works?

 

[Reloadron]

I have been following this thread as I am a recently new reloader, and I am curious as to why everyone is recommending the OP try different powders. He stated that CFE223 gets him .5-.75 MOA consistently. Did he want to shoot tighter groups then that? If not, why have him shoot more powders when one already works?

I can't speak for the other replies but as to mine the original poster asked:

I have a really odd issue that I have found. I have a Remington 700 VTR in a .308. I have had accuracy troubles in any load, hand or factory, that is not using CFE .223 is there any reason for this? Can a rifle prefer a specific powder? Or is this all coincidence? All opinions welcome, thanks for reading!

While he is getting very good results with CFE 223 in his .308 Winchester bolt gun it likely won't hurt to expand his horizons a little trying a few other powder and bullet combinations. He also responded with:

Coincidentally enough, my groups are about 1.5 with any load and with the 2 CFE 223 loads I've developed they are around .5-.75. Thanks for the info guys! Also my twist rate is 1:8 and I have tried different weights. Heavier generally does better

After many of us gave an initial reply so during those first few replies we didn't know just how well the rifle was grouping with the CFE 223 powder. That would be my thinking anyway.

Ron

 

[bme27]

That makes sense Reloadron, thank you for the clarification

 

[Demi-human]

I have anecdotal experience with CFE Two Twenty Three and temperature.

A loading of twenty five and eight tenths in Lapua brass with a Hornady seventy five grain and CCI Four fifty SRM.

In September, on one of the last nice day of summer.
One hundred yards ten shot group, seven tenths of an inch outside to outside.(Easier for me to measure.) At six hundred fifty yards, twenty hits consecutively on the steel plate. (It is a very long wall around the swamp and down the rail road grade, so 'Clang!' is the group size.)

Two weeks ago, winter has set upon the Michigan wilds.
Same results of three quarters of an inch for ten rounds (Seven times that day) at one hundred.
However, at six hundred fifty I could not make a hit. Hardly any wind.
I reasoned they were slower in the colder temperature. I tried dialing some more elevation between shots, but between the wet conditions and the vegetation growth I could not spot impact and became frustrated after fifteen rounds. I used the remaining five for various twigs and leaves closer to one fifty. (I am shooting DOWN into a swamp.) All gently fell off the tree.

The other ten were to see if I could vaporize a fifty five grain SPSX. Yes.

I think there is variation with temperature change. With only one hundred and six hundred fifty yards at this local, I was unable to discover the extent of it.
Maybe in the spring I can hash it out. Pistol season is now upon me. I don't like to lay in the snow as much as I used to.

 

[Reloadron]

Two weeks ago, winter has set upon the Michigan wilds.
Same results of three quarters of an inch for ten rounds (Seven times that day) at one hundred.
However, at six hundred fifty I could not make a hit. Hardly any wind.

That's because you were shivering and freezing your butt off on the firing line.

Seriously I have seen guys show up for summer matches and have a small cooler in tow. The idea being not as much the temperature but having their ammunition at a uniform temperature. They place a freezer bag in the bottom of a small 6 pack cooler, a layer of newspaper and then the ammunition they plan to shoot. My fays for the range being an aortic tundra are long over. Winters I clean off the handguns and visit the indoor range.

Ron

 

[Demi-human]

That's because you were shivering and freezing your butt off on the firing line. Winters I clean off the handguns and visit the indoor range.

Ron

Nah, couldn't be. It was balmy compared to this morning's negative six degrees.

I only have data for when it is nice out, unfortunately. As I conveniently "forget" my chronograph when it's less than gorgeous outside, and yet the perfect time to gather variable data. They don't work when it is snowing anyway.

I also clean out the handguns in the winter. The snow gets in there and I am petrified of rusty springs, they seem to be the Achilles heel of every mower I've had.

 

[Reloadron]

Warm here at 13.

Ron

 

[Driftertank]

Powder definitely plays a part. I had a good load for my 7mm that was a 154 SST over H4831, was a consistent sub-MOA (usually 1/2 to 3/4 MOA) load. However i had problems with it out past 600m, so i decided to try the new 162 ELD's, and wrestled with charge weight and load length variations that wouldn't get under MOA. After a bit of researching, i decided to try H1000 with the same bullets and everything clicked. Over a 4gr spread i found 2 nodes that both turned about a 3/4 MOA 5-shot group, and my biggest group of the day was about 1-1/4 MOA.

So, yeah, some guns just like certain powder/projectile combos.