Scratching head on ES and SD with good load

[WVELK]

Posted on another forum so if you are seeing twice I apologize. I am shooting a 7MM Rem Mag. The load is 68.7 grains of RL 26. The bullet is a 162 Hornady ELD-X. The barrel a carbon proof. I full length resize with a redding bushing die. I use a .305 busing followed by a .2815 mandrel. Seating is .035 off the lands. I have done extensive powder, seating and neck tension testing at 100,300 and 500. This is the best load I have. It is very consistent and even though it using runs about .65 MOA at 500 the ES and SD seem terrible. The load stays the same (pretty good for hunting), but I keep thinking I need to tweek something to improve ES and SD and then the load would tighten up a bit. Overall I almost always get three that are very tight and drop one low. I understand that could be me and not the load. Thoughts on things to test, change, or do differently???

 

[satchamo]

This may seem bassackwards but Id be checking the gun and scope first if all your test loads are doing that. Action screws torqued? Nothing contacting the barrel? Rings and bases torqued?

 

[BBob]

If the target gives you what you want at the ranges you want to hunt then just forget about the other stuff, it just doesn’t matter.

 

[KyleR1985]

Have you shot 20-30 at that distance?

One “dropping out” could be you, neck tension consistency due to brass hardness variability, powder charge precision, a butterfly flapped its wings, etc.

If you shot 30, and they all grouped but one or two fell out, I think you might be on to something. I’m a reloading dummy, but it seems hard to tell much from 5 holes at 500 yards, when they’re that tight. Other than that you can shoot well, and your gun does too.

Seems like establishing a cone of fire there makes sense

 

[WVELK]

Have you shot 20-30 at that distance?

One “dropping out” could be you, neck tension consistency due to brass hardness variability, powder charge precision, a butterfly flapped its wings, etc.

If you shot 30, and they all grouped but one or two fell out, I think you might be on to something. I’m a reloading dummy, but it seems hard to tell much from 5 holes at 500 yards, when they’re that tight. Other than that you can shoot well, and your gun does too.

Seems like establishing a cone of fire there makes sense

That is a good point. The most I have tested at one time is a 5 shot group. I do usually have one shot that drops low whether a 4 or 5 shot group. My gut tells me it is either me, or a difference in powder charge for that one shot; maybe an extra 1/10 or less a 1/10. And, as others have said, it is a pretty darn good group for 500 regardless.

On the other hand, I have a load worked up for Berger 168s. It has an ES of under 17 and the SD is around 7 or 8 as I recall and it barely shoots 1 MOA.

 

[Vern400]

Use your ballistic calculator and input the highest and lowest velocity. See how much vertical spread you have at the range you are shooting. If you're shooting 0.65 MOA at 500 yd, the calculations should agree that it's possible. Have you done that yet?
The calculator should tell you how much vertical dispersion you have in the absence of firearm and shooter variation. If the calculations are bad, and your results are good, then it probably means your groups are not sufficiently large? I e, poke more holes in one point of aim.

The statistical results you're getting are not necessarily the end of the world. But you're definitely working on the right thing to confirm that what you are getting is statistically relevant, meaning very repeatable in the field.

I trust that when you say 0.65 moa, you're not deleting shots that you deem as flyers. I contend that there are no flyers. There are crappy trigger pulls.

You didn't mention barrel length. Running a slow burning powder with a short ass barrel can cause some pretty wild SD and ES. I recently shot a batch with an unfavorable powder out of a gas gun and got an ES of 157. That's a combustion problem.

 

[wapitibob]

Posted on another forum so if you are seeing twice I apologize. I am shooting a 7MM Rem Mag. The load is 68.7 grains of RL 26. The bullet is a 162 Hornady ELD-X. The barrel a carbon proof. I full length resize with a redding bushing die. I use a .305 busing followed by a .2815 mandrel. Seating is .035 off the lands. I have done extensive powder, seating and neck tension testing at 100,300 and 500. This is the best load I have. It is very consistent and even though it using runs about .65 MOA at 500 the ES and SD seem terrible. The load stays the same (pretty good for hunting), but I keep thinking I need to tweek something to improve ES and SD and then the load would tighten up a bit. Overall I almost always get three that are very tight and drop one low. I understand that could be me and not the load. Thoughts on things to test, change, or do differently???

I'd quit using the chrono. I don't own one for the very reason you state, groups great at distance but you can't leave it alone because of the es and sd.

One flyer in 5 would concern me however, I had that issue and it was the bullet/powder combo. I don't believe that flyer is an es/sd issue. My rifle is a 7stw.

 

[WVELK]

Use your ballistic calculator and input the highest and lowest velocity. See how much vertical spread you have at the range you are shooting. If you're shooting 0.65 MOA at 500 yd, the calculations should agree that it's possible. Have you done that yet?
The calculator should tell you how much vertical dispersion you have in the absence of firearm and shooter variation. If the calculations are bad, and your results are good, then it probably means your groups are not sufficiently large? I e, poke more holes in one point of aim.

The statistical results you're getting are not necessarily the end of the world. But you're definitely working on the right thing to confirm that what you are getting is statistically relevant, meaning very repeatable in the field.

I trust that when you say 0.65 moa, you're not deleting shots that you deem as flyers. I contend that there are no flyers. There are crappy trigger pulls.

You didn't mention barrel length. Running a slow burning powder with a short ass barrel can cause some pretty wild SD and ES. I recently shot a batch with an unfavorable powder out of a gas gun and got an ES of 157. That's a combustion problem.

All good feedback. Let me address, I am sooting a 26 inch Proof Carbon Barrel. I am NOT culling out any shots or “flyers”. The ballistic calculator is a good idea, and will look at it this evening. My wife and daughter think we need to take the boat out in 15 minutes. The are not nearly as concerned about accuracy of any rifle LOL>

 

[waspocrew]

I wouldn’t worry about the ES. If your load is repeatable and gives good accuracy at the distance you plan to hunt, shoot on.

You’ll burn through loads of components chasing small numbers.

 

[AkMtnRunner]

Good groups with larger ES/SD sometimes happen and is not necessarily a problem. The ES/SD is more critical beyond 600 yards.

Agree that getting larger sample size is a great idea.

 

[WVELK]

Use your ballistic calculator and input the highest and lowest velocity. See how much vertical spread you have at the range you are shooting. If you're shooting 0.65 MOA at 500 yd, the calculations should agree that it's possible. Have you done that yet?
The calculator should tell you how much vertical dispersion you have in the absence of firearm and shooter variation. If the calculations are bad, and your results are good, then it probably means your groups are not sufficiently large? I e, poke more holes in one point of aim.

The statistical results you're getting are not necessarily the end of the world. But you're definitely working on the right thing to confirm that what you are getting is statistically relevant, meaning very repeatable in the field.

I trust that when you say 0.65 moa, you're not deleting shots that you deem as flyers. I contend that there are no flyers. There are crappy trigger pulls.

You didn't mention barrel length. Running a slow burning powder with a short ass barrel can cause some pretty wild SD and ES. I recently shot a batch with an unfavorable powder out of a gas gun and got an ES of 157. That's a combustion problem.

Interesting the average speed between the three grouped in a triangle compared to the speed of the lowest shot creates a 1 inch drop on the ballistic calculator. I have about a 2 inch drop with the lower shot from center of upper group and the lowest shot.

 

[tjv66]

How much time between each shot?

I just recently put a 300wsm together on a proof carbon barrel and I’m not completely sold on the carbon barrel. I’ll get weird fliers when shooting back to back 3-5 shot groups, but if I sit and wait 10 minutes between shots and the barrel cools down it will shoot great. My barrel doesn’t like to get hot.

 

[WVELK]

How much time between each shot?

I just recently put a 300wsm together on a proof carbon barrel and I’m not completely sold on the carbon barrel. I’ll get weird fliers when shooting back to back 3-5 shot groups, but if I sit and wait 10 minutes between shots and the barrel cools down it will shoot great. My barrel doesn’t like to get hot.

I set a timer and have 2 minutes between each shot, and 10 minutes between each 4 shot group.

I will test your theory soon because I got a fan to blow air through the barrel between strings and maybe shots.

 

[aachey]

If you’ve played with all the variables you can and it doesn’t fix it, clearly something with the combination just isn’t working. Maybe try different lot of powder (if you have one) or throw another bullet in front of it and see what that does.

 

[112Savage]

Your ES/SD match meaning ES is 57; 2 SD’s (one up and one down) would be 40fps and should comprise 62% of your shots. 4 SD’s would be 80fps and contain 97% of your shots.

I would mark the brass that is hitting lower and see if that/those brass consistently throw shots

Otherwise the thrown shots could be shooter error

 

[HandgunHTR]

I don't see where anyone has asked, so I will.

How are you weighing your powder charges? If your scale is only accurate to +/- 0.1 grain, that would easily account for the swing in velocity, especially with a powder like RL26.
While you have already experienced the fact that not all loads that have good numbers provide good groups, in my experience if you find a load that gives good groups and are able to improve the numbers, the groups get better (as long as you are not the cause).

So, I would start with the powder delivery and weighing system, then go to neck tension. You also didn't say if you are annealing. Going down (bushing) and then back up (mandrel) each time then expanding through firing is a lot of work on those necks. So, unless you are only firing them 2-3 times and then pitching them, annealing after each firing with a repeatable method (not torch and drill) will help get consistent neck tension. The final thing I will ask is, what brass? If your brass is not consistent in volume you will have small variations in internal capacity, leading to inconsistent pressures. Try weight sorting your brass and load them by weight category groupings and see if that helps.

 

[Dmoua]

What brass?

 

[mtnbound]

Posted on another forum so if you are seeing twice I apologize. I am shooting a 7MM Rem Mag. The load is 68.7 grains of RL 26. The bullet is a 162 Hornady ELD-X. The barrel a carbon proof. I full length resize with a redding bushing die. I use a .305 busing followed by a .2815 mandrel. Seating is .035 off the lands. I have done extensive powder, seating and neck tension testing at 100,300 and 500. This is the best load I have. It is very consistent and even though it using runs about .65 MOA at 500 the ES and SD seem terrible. The load stays the same (pretty good for hunting), but I keep thinking I need to tweek something to improve ES and SD and then the load would tighten up a bit. Overall I almost always get three that are very tight and drop one low. I understand that could be me and not the load. Thoughts on things to test, change, or do differently???

I would shoot a larger round count and get more data before chasing anything. What is your accuracy goal?

 

[huntsd]

Is you max past 500? If your max is 500 why mess with it? That’s a great group. Es won’t come into play unless you start stretching it out.

 

[WVELK]

Is you max past 500? If your max is 500 why mess with it? That’s a great group. Es won’t come into play unless you start stretching it out.

My max for hunting this year is probably 600. I would however have to have a load that is stable and good out to 1,000. I have some friends that shoot regularly at that range and I would like to join the club so to speak. I was use to shooting recurve bows at 90 meters so I think surely I can shoot a rifle at 1,000 LOL