Can I expect every listedpowder on a cartridge to get good SD or only the best powder

[deerslayer]

So my question is can I only expect really low SD with the perfect powder or can it be done with most powders on a given load that is in book.
I’ve recently got a Labradar and started developing some what I hope will be high precision loads. All brass was new, prepared and full length sized, trimmed within .001, chamfered, all primers set by hand with hand primer. Bullets seated and all rounds checked OAL on ogive measurements and everything was within .001”. Runout was good on all rounds under .002 on ogive. Water weight tested all cases after firing and capacities all within 1grn, dry case weights were selected +- 1 grn.

First attempt was with 300wm tssx 180 grn, using h4350 and the best ES I could get was around 60 and SD around 19, this was after doing a safe work up and then a 10 shot test and loading to the flat spots. Just didn’t make me happy and the accuracy was horrendous (I realize I can fiddle with case length and probably correct this but why waste time and components if ES is bad)

Second attempt 300wm 168 grn Hornady match bullet, using h414 powder, again slow work up and a three different flat spots I tried and even the best one had a Es of 75 and sd of 18. These were extremely accurate at 100, however the ES is to high to move on out with.

So should I try different powders, or look more at my process to lower these numbers?

[country gent]

Neck tension, crimp, case capacity, primers, all have a direct bearing on ES SD. Powders may burn better in different pressure ranges than others do. Finding the sweet spot is the trick. Bullet weight may also have an effect here.

A 60 fps es on a load at 3000 fps is much less than one at 1500 fps. SD is a statistical measurement, its normally higher with smaller number of rounds fired. Trying different primers may help some both STD and Magnum. The slower powders are harder to ignite and may need more pressure to burn right

[deerslayer]

Neck tension, crimp, case capacity, primers, all have a direct bearing on ES SD. Powders may burn better in different pressure ranges than others do. Finding the sweet spot is the trick. Bullet weight may also have an effect here.

A 60 fps es on a load at 3000 fps is much less than one at 1500 fps. SD is a statistical measurement, its normally higher with smaller number of rounds fired. Trying different primers may help some both STD and Magnum. The slower powders are harder to ignite and may need more pressure to burn right

As far as neck tension I did try with and without a lee factory crimp die and it was almost no difference. I am using a standard full length die with and expander ball.

[deerslayer]

Neck tension, crimp, case capacity, primers, all have a direct bearing on ES SD. Powders may burn better in different pressure ranges than others do. Finding the sweet spot is the trick. Bullet weight may also have an effect here.

A 60 fps es on a load at 3000 fps is much less than one at 1500 fps. SD is a statistical measurement, its normally higher with smaller number of rounds fired. Trying different primers may help some both STD and Magnum. The slower powders are harder to ignite and may need more pressure to burn right

60 FPS extreme spread is pretty substantial when we get to long range stuff. 60 FPS at 700 yds could be missing the target entirely.

[lawdog941]

I find that if all details were followed in loading for accuracy, there will be some powders that just won't work to get low ES. Just try different powders. Another item, try a magnum primer with large volume ball powder.

[deerslayer]

I have been using magnum primers, I will be trying another powder for sure. What would lead one to the best powder for lower ES, would it be case fill capacity or ?? I just ordered a neck mandrel I wanna mandrel size some and see if that little change in my process can improve things.

[Tim357]

IME, SD doesn't mean diddly-squat as long as the holes in the target are close together. Trigger time and practice makes for meat in the pan moreso than a small SD. YMMV, but I don't sweat it if the bullets go where i want them to go.

[lawdog941]

On powders for the 300WM, look to H1000, Retumbo burn rates area. There is a lot of info over at longrangehunting.com on their forums for the 300WM.

[Larry Gibson]

A 60 fps ES with a 19 fps SD out of a 300 WM given a 10 shot test is actually pretty good. You'll read of single digit SDs and lower ESs but most are with 3 or sometimes 5 shot tests. The more you chronograph different loads you'll see that.

To answer your question; "So my question is can I only expect really low SD with the perfect powder or can it be done with most powders on a given load that is in book."?

You can but I would look at slower burning powders such as H4831 or RL 22 to get as close to 100% load density as possible. Weighing the charges for consistency is critical to your goal. I would also use a magnum strength primer.

[deerslayer]

IME, SD doesn't mean diddly-squat as long as the holes in the target are close together. Trigger time and practice makes for meat in the pan moreso than a small SD. YMMV, but I don't sweat it if the bullets go where i want them to go.

If the loads right in the 300 I’m using I’ll put 5 on a quarter easy enough at 115 yds, the h414 load above was 1 moa, but the ES was to far apart for longer range accuracy.

[deerslayer]

On powders for the 300WM, look to H1000, Retumbo burn rates area. There is a lot of info over at longrangehunting.com on their forums for the 300WM.

Thank you I’ll check that out, looks like the h1000 will be a really compressed load. Is that good for lowering ES and SD

[deerslayer]

A 60 fps ES with a 19 fps SD out of a 300 WM given a 10 shot test is actually pretty good. You'll read of single digit SDs and lower ESs but most are with 3 or sometimes 5 shot tests. The more you chronograph different loads you'll see that.

To answer your question; "So my question is can I only expect really low SD with the perfect powder or can it be done with most powders on a given load that is in book."?

You can but I would look at slower burning powders such as H4831 or RL 22 to get as close to 100% load density as possible. Weighing the charges for consistency is critical to your goal. I would also use a magnum strength primer.

I was hoping for a little more consistency on the ES in particular, the SD is some formula I’m not smart enough to understand however I hear single digits is the goal.
I’ll definitely be trying a slower powder I have some 4831 I may give that a go.
As far as weighing charges I have the hornady auto charge pro, and every time I check it against the Ohauss 10-10 it’s money.

[Tim357]

If the loads right in the 300 I’m using I’ll put 5 on a quarter easy enough at 115 yds, the h414 load above was 1 moa, but the ES was to far apart for longer range accuracy.

But did you shoot at longer range, or is this a SWAG?

[deerslayer]

But did you shoot at longer range, or is this a SWAG?

I haven’t tried them past 400 yet, I was able to hit the steel however the poi wasn’t consistent. As far as exact moa at that distance I didn’t do it on paper. The same rifle using Berger’s factory stuff is fantastic at that distance and will shoot a group you can cover with a softball if you do your part.

[Larry Gibson]

I was hoping for a little more consistency on the ES in particular, the SD is some formula I’m not smart enough to understand however I hear single digits is the goal.
I’ll definitely be trying a slower powder I have some 4831 I may give that a go.
As far as weighing charges I have the hornady auto charge pro, and every time I check it against the Ohauss 10-10 it’s money.

Yes, "single digit" SDs are a goal but seldom achieved consistently with 10 shot tests. Also with some cartridge they are more easily obtained. A 300 WM in a rifle with less than a 26" barrel is not one of those cartridges. I have chronographed (10 shot tests) the best of several different very high quality 300 WM loads out of M24 rifles used for very long range shooting. The ES of those loads averaged around 40 - 75 fps. Those ESs with the bullets used at 300 WM velocities for those bullets can correlate to less than 1/2 moa (5") of vertical dispersion at 1000 yards, usually much less.

What I'm telling you is based on actual chronographing a lot of loads in many different cartridges and guns since '74. In the last 13+ years, since I started pressure testing, I have tested close to 3000 different 10 shot tests. Occasionally, actually very seldom, is there any cartridges that consistently give SDs in the single digit much less any ESs. Even then, of those rare instances, it is seldom repeatable. Low SD and ES with some cartridges can be done but to expect consistent single digit ES out of a 300 WM.......the odds are better at winning the lottery or getting struck by lightening.

Out of my M70 Target rifle in .308W my LR match load of the 175 MK over Varget for 2750 fps give SDs of 16 - 20 fps with ESs of 40 - 60 fps. That SD and ES range is pretty much the same out of my Savage Competition M12 with a 29 1/2" Palma barrel on it with the best of Federal match loads or my own match loads.

Attachment 275106

Attachment 275107

Out of my M70 in 30-06 the last test (10 shots at 300 yards) of my LR load [178 Sierra MK over 100% load density of IMR 4831] averaged 3050 fps with a 12 fps SD and an ES of 36 fps. The 300 yard ten shot group ran 1.6" or just over 1/2 moa.

Attachment 275108

Attachment 275109

In your 300 Win mag with jacketed bullets continue to weigh the charges. Use a powder that give the best performance [velocity and SD/ES] at as close to 100% load density as possible. Also the bullet weight should be compatible with the twist and powder used. Truthfully the 168 gr bullet is a bit on the light side. A 178 to 220 gr match bullet would be a better choice.

[lotech]

Opinions vary, but it seems there is far too much emphasis and SD and ES numbers among some shooters. Small numbers don't equate to an accurate load, though it's certainly possible to have an accurate load that also has small SD and ES numbers. If I have an accurate cast or jacketed bullet load, I don't pay attention to the numbers. Consistent group size is far more important.

However, I don't shoot cast rifle bullets beyond 200 yards and don't shoot jacketed beyond 400 yards. At greater distances, SD and ES figures may become more meaningful.

[lawdog941]

Yes, "single digit" SDs are a goal but seldom achieved consistently with 10 shot tests. Also with some cartridge they are more easily obtained. A 300 WM in a rifle with less than a 26" barrel is not one of those cartridges. I have chronographed (10 shot tests) the best of several different very high quality 300 WM loads out of M24 rifles used for very long range shooting. The ES of those loads averaged around 40 - 75 fps. Those ESs with the bullets used at 300 WM velocities for those bullets can correlate to less than 1/2 moa (5") of vertical dispersion at 1000 yards, usually much less.

What I'm telling you is based on actual chronographing a lot of loads in many different cartridges and guns since '74. In the last 13+ years, since I started pressure testing, I have tested close to 3000 different 10 shot tests. Occasionally, actually very seldom, is there any cartridges that consistently give SDs in the single digit much less any ESs. Even then, of those rare instances, it is seldom repeatable. Low SD and ES with some cartridges can be done but to expect consistent single digit ES out of a 300 WM.......the odds are better at winning the lottery or getting struck by lightening.

Out of my M70 Target rifle in .308W my LR match load of the 175 MK over Varget for 2750 fps give SDs of 16 - 20 fps with ESs of 40 - 60 fps. That SD and ES range is pretty much the same out of my Savage Competition M12 with a 29 1/2" Palma barrel on it with the best of Federal match loads or my own match loads.

Attachment 275106

Attachment 275107

Out of my M70 in 30-06 the last test (10 shots at 300 yards) of my LR load [178 Sierra MK over 100% load density of IMR 4831] averaged 3050 fps with a 12 fps SD and an ES of 36 fps. The 300 yard ten shot group ran 1.6" or just over 1/2 moa.

Attachment 275108

Attachment 275109

In your 300 Win mag with jacketed bullets continue to weigh the charges. Use a powder that give the best performance [velocity and SD/ES] at as close to 100% load density as possible. Also the bullet weight should be compatible with the twist and powder used. Truthfully the 168 gr bullet is a bit on the light side. A 178 to 220 gr match bullet would be a better choice.

Larry's the man with the answers!

[Harter66]

You mentioned 1 gr of case weight and water volume in your weigh lots .

There's a lot of room for error there . I weighed a bunch of 06' once and had 17gr of case weight for 10 gr of water volume . I had a rifle that would throw a bullet out 4-6" for 3 gr of case weight . Keep cases to 1/2 gr of water and 1.5 case weight and 5 shots would go into .690 CTC .

1 gr of case weight isn't much it's about the same as 1 pellet of #4 lead shot , not much volume at all at 13.5-14.7 psi . Ambient atmosphere . But it's a lot bigger at 40-55kpsi . Pressure volume and s probably most relatable in a visual sense of 1 gallon of water making 17,000 cuft of 12# steam . I can't say , I've never done the math , but 3,000 of those little bitty #4 pellets is probably about the size of a softball , 45,000÷14.7 is round numbers 3000 so just as an eyeball lay mechanics reference .

A little case variation goes a long way when you start looking at chamber pressure vs muzzle vs ambient .

A low ES/SD may not be anywhere near talking to your barrel , just because it gets to the muzzle at the same time doesn't mean the muzzle is going to be in the same place every time .

The mechanics that go on in the .0012 seconds or so between the sear break an muzzle exit .......temp , altitude , stock pressure , ......... Body oil on the case or bullet from a finger print ...... Going on out to the extremes where .01" 500 yd dispersion is the difference between 1st and 10th .

If your not a competitor don't wring your brain out about it . Shoot 10 then 20 or 50 or whatever on paper with a with a minimum variation hold when you get down to a 2 caliber group at 100 and 4 at 200 then you can start dissection of the minutiae like finding the 105% case cap load for your .5% variation cases .

[downzero]

IME, SD doesn't mean diddly-squat as long as the holes in the target are close together. Trigger time and practice makes for meat in the pan moreso than a small SD. YMMV, but I don't sweat it if the bullets go where i want them to go.

The shots will never be close together at long range if the SD isn't low. The vertical difference is completely based on time to target, which is perfectly correlated to the speed it leave the muzzle at.

What matters most to getting low SDs is getting the pressure up. Combustion is more consistent at higher pressures, that is why compression ratios in cars went from 4:1 in the 20s to 8:1 and with fuel injection, higher is possible (mine is 10.9:1 on 91 octane).

Your rifle is no different. Choose the slowest burning powders and find the highest accurate node and you will get your long range accuracy. As others have said, for magnum rifle that's going to be H1000/Retumbo area in the the burn rate chart.

Playing with seating depth only happens after you find an accurate load. If your rifle is like mine, it will almost always want the cartridges as close to the lands as it can get, and with VLDs, even jammed into the lands. Obviously if you're going to go that far, make sure you back the loads down some first.