causes of big ES spreads

Do old powder cause big extreme spreads? Tried the old IMR7828 in the can for my 7 Mag and 160 Accubonds and ES is awful and jumping back and forth between 20 to 100 fps. Checked the color of the powder and it looks normal. All my brass is prepped properly and annealed.

The age of the powder would have no discernible effect on velocities. Perhaps oxidation of the powder; but you would have noticed any significant oxidation. Extreme spread is due to non-optimal burn rates, which are influenced by case fill, compaction of propellant, etc.

Do you use the same components with different powders and get normal ES? I only have one can powder, 5 pounds of 700x, generally only load it in 38/357 and some cast 9mm, so I don't check velocity. They have a pretty consistent feel in the hand, and with my smaller 9mm pistols have a pretty consistent ejection pattern.

Are you using mixed head stamps? Mixed lots of brass? Have you checked H2O capacity? Is the rifle stock? Has it given single digit ES before? What's your load? Close to max?

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thatguySHM":1zypmo0o said:

Are you using mixed head stamps? Mixed lots of brass? Have you checked H2O capacity? Is the rifle stock? Has it given single digit ES before? What's your load? Close to max?

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Using Lapua brass, fired 5X, same lot, annealed, charges are measured on Chargemaster and then on a FX120, custom rifle Sako M995, 62, 62.4, 62.8, 63.2, 63.6, 64, 64.4 grains, 3 round groups. Yes, it has given single digits with other loads / powders. I have gotten excellent groups but ran out of bullets and culling my arsenal of bullets on the shelves. Just working up these loads with 7828 for the first time to use for deer season. Maybe I need to go back to my go to powder,,,,RL-25

Ya, if a powder is giving that kind of extreme spread, I think it would be best to go back to what works!

More than once, I've simply dumped a pound of powder that wasn't working well, on my lawn. Gotta watch where I put the Weber Kettle after that though! :grin: Might give my whole yard an extreme spread!

Guy

With 150gr Scirocco II's, I'm getting 8.7 for an ES with 4831sc and a velocity of 3110.

I was getting under 5 with RL23 and 180gr ELDS. All stuff you aren't asking about, I know the 7 Rem Mag is very capable of low spreads as you know as well. I've always used a stiff load of RL22 with 160 Accubonds and it's been killer in every 7mm I've tried it in. 25 should be just as good. I haven't tried 26 yet, but folks seem to absolutely stand behind it. Just another option.

How old is the brass? Lapua 7 Mag sounds old to me.. been awhile since they dabbled in belted mags if memory serves me..

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TackDriver284":2svpjw3e said:

thatguySHM":2svpjw3e said:

Are you using mixed head stamps? Mixed lots of brass? Have you checked H2O capacity? Is the rifle stock? Has it given single digit ES before? What's your load? Close to max?

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Using Lapua brass, fired 5X, same lot, annealed, charges are measured on Chargemaster and then on a FX120, custom rifle Sako M995, 62, 62.4, 62.8, 63.2, 63.6, 64, 64.4 grains, 3 round groups. Yes, it has given single digits with other loads / powders. I have gotten excellent groups but ran out of bullets and culling my arsenal of bullets on the shelves. Just working up these loads with 7828 for the first time to use for deer season. Maybe I need to go back to my go to powder,,,,RL-25

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Not sure what your speeds are but your on the low side for most 7 RMs I've seen with 160 ABs and 7828. I'd look for 3000-3100 and I'd bet your ES's tighten up.

Neck tension
Primer seating
Power measure accuracy
Bullet seating variations

Those are the common causes.... Especially bullet seating and neck tension.

Everything Ridgerunner said are some of the places I would check first. Sometimes the cure is as simple as switching primers, maybe not by a huge margin, but by enough to measure. I noticed ES improved by switching from large rifle primers, to magnum primers. Especially if I'm using a slow burning powder. I have also seen it not make any diffrence one way or the other no matter what primer was used. Over all I would probably say accurately measuring your powder, consistent seating depth, and a consistent neck tension over all will make the most notable difference.

But then all of this at times can seem like black magic soooo..

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thatguySHM":fs2n1n1w said:

How old is the brass? Lapua 7 Mag sounds old to me.. been awhile since they dabbled in belted mags if memory serves me..

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Sorry for being absent minded, its Norma brass.

SJB358":3eqkuh4h said:

TackDriver284":3eqkuh4h said:

thatguySHM":3eqkuh4h said:

Are you using mixed head stamps? Mixed lots of brass? Have you checked H2O capacity? Is the rifle stock? Has it given single digit ES before? What's your load? Close to max?

Sent from my XT1650 using Tapatalk

Click to expand...

Using Lapua brass, fired 5X, same lot, annealed, charges are measured on Chargemaster and then on a FX120, custom rifle Sako M995, 62, 62.4, 62.8, 63.2, 63.6, 64, 64.4 grains, 3 round groups. Yes, it has given single digits with other loads / powders. I have gotten excellent groups but ran out of bullets and culling my arsenal of bullets on the shelves. Just working up these loads with 7828 for the first time to use for deer season. Maybe I need to go back to my go to powder,,,,RL-25

Click to expand...

Not sure what your speeds are but your on the low side for most 7 RMs I've seen with 160 ABs and 7828. I'd look for 3000-3100 and I'd bet your ES's tighten up.

Click to expand...

On the chrono, maximum velocity of the maximum charges of 64.5 grains was 2930 fps. I expected faster speeds and Nosler manual states 64 grains as maximum. I remember pushing a 168 VLD at 3,025 fps with RL-25

What would maximum charge of 7828 be for the 160 AB?

I have done brass prepping the same way I have done as usual, very accurately and carefully, seated all primers flush with the RCBS hand tool, even uniformed primer pocket evenly, cleaned pockets, weighed each charge to the kernel and I am about to pull my hair out on what the issue can be. :mrgreen:

As most of you said, try the H4831SC, Retumbo, RL26, etc,,,I have all those plus RL25 except the RL26 and to push it to speeds of 3,000 to 3,100 fps. The 7828 filled case was not even full so I'll make a switch to the other powders to get better case fill to get lower ES. I cannot even remember the last time I used 7828, must have been about 20 years ago for the 7STW.

Thanks guys.

A 160 AccuBond at 3,000 - 3,100 fps is about as deadly as it gets... And usually very accurate.

Looking forward to further range reports, and hopefully a great field report of a big ol' mule deer buck, or a bull elk or something!

Guy

is this some of your annealed brass ? if it is , did you brush the inside of the case necks to smooth them out .
I notice my necks get rough , or gritty feeling , from annealing . it's kind of like the heat stands up the grain of the brass . I brush my necks pretty good , and I also dip my bullets in powder graphite before seating .

jimbires":2xeb2g0c said:

is this some of your annealed brass ? if it is , did you brush the inside of the case necks to smooth them out .
I notice my necks get rough , or gritty feeling , from annealing . it's kind of like the heat stands up the grain of the brass . I brush my necks pretty good , and I also dip my bullets in powder graphite before seating .

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Yes Jim, I usually use a worn copper brush and wrap a thin layer of very fine steel wool around the brush and chuck the brush in a drill and snug fit the brush inside the necks and clean them. I was sure they were clean.

Guy Miner":1b62jdjt said:

A 160 AccuBond at 3,000 - 3,100 fps is about as deadly as it gets... And usually very accurate.

Looking forward to further range reports, and hopefully a great field report of a big ol' mule deer buck, or a bull elk or something!

Guy

Click to expand...

Soon, real soon. Hopefully recover a perfectly mushroomed 160 AB, but at that speed I doubt it. :grin:

TackDriver284":wfsy0us5 said:

Guy Miner":wfsy0us5 said:

A 160 AccuBond at 3,000 - 3,100 fps is about as deadly as it gets... And usually very accurate.

Looking forward to further range reports, and hopefully a great field report of a big ol' mule deer buck, or a bull elk or something!

Guy

Click to expand...

Soon, real soon. Hopefully recover a perfectly mushroomed 160 AB, but at that speed I doubt it. :grin:

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I doubt it too .

TackDriver284":1y4e6f0x said:

SJB358":1y4e6f0x said:

TackDriver284":1y4e6f0x said:

thatguySHM":1y4e6f0x said:

Are you using mixed head stamps? Mixed lots of brass? Have you checked H2O capacity? Is the rifle stock? Has it given single digit ES before? What's your load? Close to max?

Sent from my XT1650 using Tapatalk

Click to expand...

Using Lapua brass, fired 5X, same lot, annealed, charges are measured on Chargemaster and then on a FX120, custom rifle Sako M995, 62, 62.4, 62.8, 63.2, 63.6, 64, 64.4 grains, 3 round groups. Yes, it has given single digits with other loads / powders. I have gotten excellent groups but ran out of bullets and culling my arsenal of bullets on the shelves. Just working up these loads with 7828 for the first time to use for deer season. Maybe I need to go back to my go to powder,,,,RL-25

Click to expand...

Not sure what your speeds are but your on the low side for most 7 RMs I've seen with 160 ABs and 7828. I'd look for 3000-3100 and I'd bet your ES's tighten up.

Click to expand...

On the chrono, maximum velocity of the maximum charges of 64.5 grains was 2930 fps. I expected faster speeds and Nosler manual states 64 grains as maximum. I remember pushing a 168 VLD at 3,025 fps with RL-25

What would maximum charge of 7828 be for the 160 AB?

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I agree with Scotty, 2930 fps sounds pretty slow for a 7mm Rem Mag, I bet when you load it to where a 7mm Rem Mag should be for speed IMR 7828 will likely work better. It's a bit of a shame that so much data for that round is so under loaded.

DrMike":1physu72 said:

The age of the powder would have no discernible effect on velocities. Perhaps oxidation of the powder; but you would have noticed any significant oxidation. Extreme spread is due to non-optimal burn rates, which are influenced by case fill, compaction of propellant, etc.

Click to expand...

Thanks Mike.

Gerry, I have pushed it faster with other powders and accuracy was improved with max / or over maximum charges, just don't get it why 7828, which is the slowest powder on the IMR line of powders, did not push it faster even at maximum charges at 3000 fps or over. I just wonder if I can go over maximum of the 7828 charges by a few grains to get the speed. I did go over max by half a grain but still at 2930 fps.

I am about to load them up with RL-25 and Retumbo right now and see what results I will get. I am sure I can push it over 3000 fps with these two.

I would guess based on your speed you could go a bit higher, carefully of course. Did a bit of work last year with IMR 7977 (and IMR 4451 too) and the 154 gr Hornady, it is slower burning than 7828 and it seemed to work quite well in the limited work I did with it. Your plan of using RL 25 and Retumbo is a good plan and it sounds like guys using RL 26 are really liking it as well.