ES of 97?

[Hecouldgoalltheway]

So I had a load worked up for my 18" 6.5cm with 123 eld-x and 48gr of superformance. I tested the load back in probably... May, and it was spectacular, shot a half minute. Had a MV of 2919 over a 5-10 shot (I don't remember the incident) string, and excellent accuracy. So then I let my rifle sit in the closet with the ammo since without firing it. Yesterday I had time to run out to the range, and as I started moving out, my dope was obviously wrong. I backed up to 200y, confirmed zero, and it was good, and that's when I looked down at the garmin. I was getting 40fps variation from one round to the next. I ultimately ended up having an ES of 93 over 20 rounds. I've never even heard of such a thing. What could cause such ridiculous variance in velocity, other than bad powder measuring, (I am going to pull bullets and test powder charges just to be sure, but I'm very careful while loading, double checking the charge weights at least every 4 or 5 rounds). I doubt that's the problem. The brass was virgin sig brass. My buddy seems to think that it could be causing problems, but I've shot it for years without trouble. Where else should I look for this problem? Thank you

 

[rustyinbend]

Did your ammo also sit for months, or did you build for this range trip?

 

[Hecouldgoalltheway]

Did your ammo also sit for months, or did you build for this range trip?

No, it sat for months, but it was inside my house. 68° and ambient humidity.

 

[ShtrRdy]

Virgin brass could be the problem in a couple different ways. The dimensions on new brass typically do not match your chamber and resizing die. The other thing is new, clean, brass neck and bullet can form a welding action to where the bullet is stuck to the brass .

 

[Bsnyder]

That powder isn’t known for being the most temp stable. That could be part of it

 

[Chris1972]

My guess is Superformance. Developed in warm weather with enough pressure for consistent combustion but is a temp sensitive powder and is no longer igniting consistently due to low pressure. It too damn cold outside for that load.

Note: I have not seen this with this powder but have with others so just a guess

 

[Bsnyder]

I saw it in a 6 creed years back. It was pretty bad all the time anything over 85 degrees and under 40 stuff went haywire

 

[357Max]

So I had a load worked up for my 18" 6.5cm with 123 eld-x and 48gr of superformance. I tested the load back in probably... May, and it was spectacular, shot a half minute. Had a MV of 2919 over a 5-10 shot (I don't remember the incident) string, and excellent accuracy. So then I let my rifle sit in the closet with the ammo since without firing it. Yesterday I had time to run out to the range, and as I started moving out, my dope was obviously wrong. I backed up to 200y, confirmed zero, and it was good, and that's when I looked down at the garmin. I was getting 40fps variation from one round to the next. I ultimately ended up having an ES of 93 over 20 rounds. I've never even heard of such a thing. What could cause such ridiculous variance in velocity, other than bad powder measuring, (I am going to pull bullets and test powder charges just to be sure, but I'm very careful while loading, double checking the charge weights at least every 4 or 5 rounds). I doubt that's the problem. The brass was virgin sig brass. My buddy seems to think that it could be causing problems, but I've shot it for years without trouble. Where else should I look for this problem? Thank you

Bad powder choice IMO. I'd expect ES/SD to suck since your only getting 85% burn in an 18" barrel. Cold temps will only make it worse.

Try 41.5 of RL 15.5

 

[rustyinbend]

No, it sat for months, but it was inside my house. 68° and ambient humidity.

Maybe just ladder test a couple grains up and down, and see if you can find a node to stabilize your ES and SD.
(This is the part where the anti-ladder contingent filets me.)

 

[Doom]

So I had a load worked up for my 18" 6.5cm with 123 eld-x and 48gr of superformance. I tested the load back in probably... May, and it was spectacular, shot a half minute. Had a MV of 2919 over a 5-10 shot (I don't remember the incident) string, and excellent accuracy. So then I let my rifle sit in the closet with the ammo since without firing it. Yesterday I had time to run out to the range, and as I started moving out, my dope was obviously wrong. I backed up to 200y, confirmed zero, and it was good, and that's when I looked down at the garmin. I was getting 40fps variation from one round to the next. I ultimately ended up having an ES of 93 over 20 rounds. I've never even heard of such a thing. What could cause such ridiculous variance in velocity, other than bad powder measuring, (I am going to pull bullets and test powder charges just to be sure, but I'm very careful while loading, double checking the charge weights at least every 4 or 5 rounds). I doubt that's the problem. The brass was virgin sig brass. My buddy seems to think that it could be causing problems, but I've shot it for years without trouble. Where else should I look for this problem? Thank you

Shooting at 100 yds you can have a 100 fps velocity variation and the POI effect is about 1 caliber so it's hard to discern in a 1/2 MOA rifle. As for the change if any its likely due to ambient temperature or possibly charge weight. However, without knowing your charge weight we are pretty limited in analyzing what is going on. If it is charge weight it is large, likely over a grain. It is much more likely you are having case prep issues. I am also suspicious of your powder selection. That powder is slow, and would not be one that I would think would be good in light bullets in 6.5CM. I will say this, your velocity is for an 18.5" barrel,

 

[Hecouldgoalltheway]

Shooting at 100 yds you can have a 100 fps velocity variation and the POI effect is about 1 caliber so it's hard to discern in a 1/2 MOA rifle. As for the change if any its likely due to ambient temperature or possibly charge weight. However, without knowing your charge weight we are pretty limited in analyzing what is going on. If it is charge weight it is large, likely over a grain. It is much more likely you are having case prep issues. I am also suspicious of your powder selection. That powder is slow, and would not be one that I would think would be good in light bullets in 6.5CM. I will say this, your velocity is for an 18.5" barrel,

Thank you. As far as the initial .5moa accuracy claim, I zero every rifle I have at 200y. I have a 390y range in my yard, and a permanent table at 200y from my burm. I'm a hunter, so 200y makes sense. This wasn't happening then. My charge weight is in the original post. As far as powder selection goes, if you open the hornady manual, I believe it is the most efficient powder on the list for this bullet/cartridge combo. Iirc, it gives the highest safe velocities of any book options. Now, I have about any powder there is for this load, and I can switch easily, and probably will. Sounds like superformance has caused issues for other folks as well, especially when the temps change.

 

[Chris1972]

I didnt even think of how slow it was just the temp stability and good combustion. That light of a bullet I would look to the other side of 4350 for sure.

 

[memilanuk]

As far as powder selection goes, if you open the hornady manual, I believe it is the most efficient powder on the list for this bullet/cartridge combo. Iirc, it gives the highest safe velocities of any book options.

Yeah... but I'm guessing that load manual data was for another 6" of barrel?

The right powder for the job sometimes changes a bit when you change the barrel length that much.

 

[Hecouldgoalltheway]

Yeah... but I'm guessing that load manual data was for another 6" of barrel?

The right powder for the job sometimes changes a bit when you change the barrel length that much.

Solid point

 

[Doom]

Thank you. As far as the initial .5moa accuracy claim, I zero every rifle I have at 200y. I have a 390y range in my yard, and a permanent table at 200y from my burm. I'm a hunter, so 200y makes sense. This wasn't happening then. My charge weight is in the original post. As far as powder selection goes, if you open the hornady manual, I believe it is the most efficient powder on the list for this bullet/cartridge combo. Iirc, it gives the highest safe velocities of any book options. Now, I have about any powder there is for this load, and I can switch easily, and probably will. Sounds like superformance has caused issues for other folks as well, especially when the temps change.

Ouch, read right over that this morning! The 200yd makes some difference more on the order of 0.3 MOA for 100 fps!. Anyway, I don't have the the latest Hornady manual with the ELD's but I'm betting their velocity is in a 24" barrel. So if it's 3000 fps then you're about on the max.

Back when that powder first came out it was highly touted as s "Wonder Powder" but it pretty quickly seemed to lose any following it developed. But since it is slow, you might try a magnum primer and see what happens.

 

[Rio Precision Gunworks]

Ammo with true to life SD of 15 will have an ES of 90 if you shoot enough rounds to get to that 3% or so. And, we don’t control when that happens. So it could do it in 20 rounds or it could take 200rnds.

Not saying that’s the case with your ammo, but most people who think they have an SD in the 5-10fps range actually have a higher actual SD than their small sample size has shown them.

This is also yet another reason why ES is a pretty terrible metric and SD is what you should be looking at. It’s only taking two data points into account over your 20 shots. You didn’t provide us with the velocities of all 20, so it could literally just be some as simple as a bad case or misthrow on powder. Or you could actually have ammo with a 15sd if you shot enough rounds to find the true SD.

 

[918v]

Clean your barrel

 

[Hecouldgoalltheway]

Ammo with true to life SD of 15 will have an ES of 90 if you shoot enough rounds to get to that 3% or so. And, we don’t control when that happens. So it could do it in 20 rounds or it could take 200rnds.

Not saying that’s the case with your ammo, but most people who think they have an SD in the 5-10fps range actually have a higher actual SD than their small sample size has shown them.

This is also yet another reason why ES is a pretty terrible metric and SD is what you should be looking at. It’s only taking two data points into account over your 20 shots. You didn’t provide us with the velocities of all 20, so it could literally just be some as simple as a bad case or misthrow on powder. Or you could actually have ammo with a 15sd if you shot enough rounds to find the true SD.

Thank you. It was literally all over the place. I witnessed 40-60 fps changes from one cartridge to the next. There was a concentration of shots in the median range, (probably 40%), but the 97 es swing was pretty realistic. If you removed the highest and lowest examples, it would have still been 80 or more.

 

[spife7980]

Dirty barrel and a wild powder are my suspicions.

How different was you average velocity compared to mays 2919? What if you throw out the top 5 and bottom 5? To get you a bit tighter velocity?
Do it again this weekend, but this time leave the cartridges in the waist of your underwear against your body to keep em warm before shooting and see if it comes back to performing with mays average velocity.

 

[ShtrRdy]

Do it again this weekend, but this time leave the cartridges in the waist of your underwear against your body to keep em warm before shooting and see if it comes back to performing with mays average velocity.

I sometimes put cartridges in my pants pocket to keep them warm. Maybe I'll try your suggestion next time. Should get some looks from other shooters.

 

[Holliday]

What I do when it is cold is keep my test ammo and a small hard cooler soaking over night at 68-70°F . Then right before I head to the range I fill a flexible water 1 liter bottle w/ 85°f water.

When I head to the range I put the water bottle and the mtm box of handloads in the cooler. The handloads maintain 65-70° while I open and pull each round in the frigid cold.