ES is 75fps with factory Ammo, 100yd Accuracy is .35”

[4wdwelder]

Hi. This is my first post here. I’m used to my 7mmRM, and just bought my first 6.5 Creedmoor. I’m trying factory ammo to see what it likes, and I’m having great accuracy, but ES is 75, but accuracy at 100 yds is .15- .35”. I haven’t tried longer range, but I assume that if I do, it won’t be consistent, and just a waste of ammo. Do I need to adjust seating depth from lands, or neck tension? Thank you for anyones feedback.

 

[rijndael]

At what distance do you plan to shoot this load? Have you run the numbers for your low velocity and high velocity, at the distances you plan to shoot it, to see if the elevation differences matter for your target size? Are you trying to get the best accuracy or is a 'field accuracy' sufficient?

My CFE223 308 loads have a high ESs too - it also groups great at 100Y (1/4 MOA). I've tried everything to reduce the SD/ES without success. I shoot it as-is. It still bangs steel at 600Y and in, which is my 308's primary job. I wouldn't shoot it at 1K and expect the same results unless my targets were huge.

 

[4wdwelder]

At what distance do you plan to shoot this load? Have you run the numbers for your low velocity and high velocity, at the distances you plan to shoot it, to see if the elevation differences matter for your target size? Are you trying to get the best accuracy or is a 'field accuracy' sufficient?

My CFE223 308 loads have a high ESs too - it also groups great at 100Y (1/4 MOA). I've tried everything to reduce the SD/ES without success. I shoot it as-is. It still bangs steel at 600Y and in, which is my 308's primary job. I wouldn't shoot it at 1K and expect the same results unless my targets were huge.

 

[4wdwelder]

I’m planning for 1000 yds, same as my 7mm. I haven’t tried it at longer ranges, because I assumed it would be pointless, because of the ES. I ran into this when making a recipe for my 7 mm, but only adjusted seating depth, not neck tension.

 

[shoot4fun]

Hi. This is my first post here. I’m used to my 7mmRM, and just bought my first 6.5 Creedmoor. I’m trying factory ammo to see what it likes, and I’m having great accuracy, but ES is 75, but accuracy at 100 yds is .15- .35”. I haven’t tried longer range, but I assume that if I do, it won’t be consistent, and just a waste of ammo. Do I need to adjust seating depth from lands, or neck tension? Thank you for anyones feedback.

What brand chronograph? On the barrel, sky screen or doppler?
How many shots are you reading? Ten shots? Five? Twenty?
I won't ask what brand of factory ammo as that just sends your thread down a bad dirt road.

 

[whatsupdoc]

If it is a brand new barrel it will need some time for the velocity to settle.

 

[Ned Ludd]

I have a .223 Rem barrel that I stupidly jammed a .30 cal cleaning rod into when it was brand new. I can't visually observe anything wrong with the chamber via borescope. Nonetheless, I did something to it with the cleaning rod because I cannot get the ES below about 60 fps with that particular barrel. For that reason, I have been using it as a fire-forming and practice barrel. At 330 yd, I have shot numerous 10-shot groups of ~0.5 MOA using that barrel, although the ES values range from about 60, to as much as 90 fps. It is even capable of shooting cleans at 600 yd in fairly benign wind conditions. At 1000 yd, I'd expect a totally different story, where the high ES would definitely show up more strongly and be a "deal-breaker".

Somewhere between 600 yd and 1000 yd is where high ES will really start to bite you. Exactly where, I can't say with any certainty. You can get away with it at shorter distances, but as the distance increases, so will the vertical dispersion. For that reason, we try to keep the ES/SD values to a minimum, even when shooting at shorter distances where the effect is much less noticeable. It terms of trying to "tame" the high ES, consistent neck tension is certainly something worth pursuing. Although you may observe velocity effects during the process, tuning with seating depth is more about optimal precision with a given load/bullet than it is about lowering ES/SD. Other considerations that are well-known to affect ES/SD might include the choice of primer, powder, and maintaining "reasonable" precision in charge weight.

The bottom line is that sometimes you simply have to test a number of variables until the culprit behind the high ES/SD can be identified and address. Rigorous brass prep and testing a couple or three different primers would be a good place to start.

 

[4wdwelder]

What brand chronograph? On the barrel, sky screen or doppler?
How many shots are you reading? Ten shots? Five? Twenty?
I won't ask what brand of factory ammo as that just sends your thread down a bad dirt road.

I’m using a supporter, barrel mounted. Reading 10 shot strings

 

[55fairlane]

Shoot em at 300 &600 yards....the group size matters.....matches aren't won or lost on the reloading bench, send 'em at distance and see what things look like

 

[shoot4fun]

I’m using a supporter, barrel mounted. Reading 10 shot strings

I feel ten shot strings are a decent enough sample size. Do you reload? Also, if you have availability, try some different brand factory ammo.
Another suggestion would be to weigh-sort a box of the ammo and try the ten that are closest in weight to see if a difference.
IMO, you won't ever really have confidence until you star loading your own.

 

[4wdwelder]

I mostly reload my own. I have my 7mm on 18” consistent to 1000. I only buy ammo when I run low on brass. I tried 5 different brands on this Creedmoor. I’ll weigh some and see how consistent they are next time I’m out. Thank you all for your input. It’s the question of neck tension vs seating depth affecting ES/SD that I was after most.

 

[shoot4fun]

I mostly reload my own. I have my 7mm on 18” consistent to 1000. I only buy ammo when I run low on brass. I tried 5 different brands on this Creedmoor. I’ll weigh some and see how consistent they are next time I’m out. Thank you all for your input. It’s the question of neck tension vs seating depth affecting ES/SD that I was after most.

So you want to take what info you got from shooting factory ammo at 100 yards and use it to make reloads with lower ES so you can shoot 1000 yards?

 

[Rset]

Hi. This is my first post here. I’m used to my 7mmRM, and just bought my first 6.5 Creedmoor. I’m trying factory ammo to see what it likes, and I’m having great accuracy, but ES is 75, but accuracy at 100 yds is .15- .35”. I haven’t tried longer range, but I assume that if I do, it won’t be consistent, and just a waste of ammo. Do I need to adjust seating depth from lands, or neck tension? Thank you for anyones feedback.

IMO shooting factory ammo will tell you nothing. Until you start to reload your own how would you know if seating depth, neck tension, or any other number of variables (powder type and charge, primer selected, bullet chosen, etc) would make a difference. Factory ammo is what it is, that's why most people don't try to compete with it.

 

[Straightshooter1]

Hi. This is my first post here. I’m used to my 7mmRM, and just bought my first 6.5 Creedmoor. I’m trying factory ammo to see what it likes, and I’m having great accuracy, but ES is 75, but accuracy at 100 yds is .15- .35”. I haven’t tried longer range, but I assume that if I do, it won’t be consistent, and just a waste of ammo. Do I need to adjust seating depth from lands, or neck tension? Thank you for anyones feedback.

If you haven't already read this article, you might want to read it as might help you better understand how ES can related to your issue:

Muzzle Velocity Stats – Statistics for Shooters Part 2

Consistent muzzle velocity is key for long-range shooting, otherwise, bullets that leave the muzzle...

precisionrifleblog.com

 

[Forum Boss]

Could be a problem with your chronograph. Suggest you test at least two more 5-shot groups.

If the 70+ ES is correct, that is very bad. But we have seen that with some factory ammo.

The velocity variance will show up at longer range in vertical.

Learn to hand-load and try to keep 5-shot ES under 20 fps, and under 15 fps is quite do-able.