More powder less velocity ?

[Sargesniper]

260 rem.
30" Bartlein Barrel 8.5 Twist
120 Gr. Hdy. A-Max
Lapua Brass
210/M Primer
Hdy. Superformance

Loaded 5 rounds each.

Velocity
# 1-- 45.0 gr 2938 FPS.
# 2-- 45.5 gr 2993 FPS.
# 3-- 46.0 gr. 3074 FPS.
# 4-- 46.5 gr. 3113 FPS.
# 5-- 47.0 gr. 3073 FPS. >>>>> ( not a typo)
# 6-- 47.5 gr. 3135 FPS.

I have heard about this from the past but this is the first time to encounter it. I load for more calibers but have only seen this in this one.
I was wondering about two things here. #1- has anyone else seen this first hand?
#2- Looking at the velocities, which one would appear to be the more accurate load for 300 + yds? if someone can determine it from my findings. I am still working on this powder bullet combo but 300 yd ranges are not common here.
Maybe some of you know the answers. Thanks in advance for any comments.
.......... SEMPER FI. SARGESNIPER

 

[Bullet bumper]

There would be a few things that could cause that not withstanding chronographs .
Did you let the gun cool down on no 5 velocity shot/s compared to the other shots ?
How hot the barrel is and how long you leave the round in the chamber before discharge can make a difference to how much heat soaks in . Some powders are worse than others.
Averaging velocities over numerous shots is more accurate .
Primer differences can contribute.
Powder variations is possible.
Charge weight variations could contribute .
Case volume could contribute .
Variations in neck tension due to variations neck wall thickness .
Projectile differences could contribute . Weight , diameter ?
Even bore fouling could contribute the pressure rises as the bore fouls but reaches a point that that one shot can strip some fouling and then the next shot in , sees less fouling than some of the previous shots.
A few things could all line up in the one cartridge and reduce pressure and that reduces velocity .
Primers do funny things I find that in a 308 case the Federal 210 is good but as soon as that case is necked to 243 and a slower powder used the Win LR primer is better , don't ask me why .
Try some different primers in the 260 Rem. and see what happens.
Keep a check on barrel heat and the time it takes to fire that round , try and standardise the firing conditions.
Uniform the flash holes and primer pockets.
Not possible top say which will shoot best at 300 yards , there is another 2 dozen things that affect group potential .
Highest velocities does not always produce best accuracy but you do need to stay supersonic at any particular range .
Standard deviation SD of numerous velocities taken is a better guide than total velocity but not fool proof . Not calling anyone a fool it's just a saying. If your chrony will not do it SD can be calculated http://easycalculation.com/statistics/standard-deviation.php but it's a string of each individual load to see which one is the most consistant .
300 accuracy should not be a problem for a 260 Rem. tuned to shoot well at 200 yards not withstanding the extra elevation drop .

 

[Sargesniper]

There would be a few things that could cause that not withstanding chronographs .
Did you let the gun cool down on no 5 velocity shot/s compared to the other shots ?
How hot the barrel is and how long you leave the round in the chamber before discharge can make a difference to how much heat soaks in . Some powders are worse than others.
Averaging velocities over numerous shots is more accurate .
Primer differences can contribute.
Powder variations is possible.
Charge weight variations could contribute .
Case volume could contribute .
Projectile differences could contribute .
Even bore fouling could contribute the pressure rises as the bore fouls but reaches a point that that one shot can strip more fouling than the previous shots and then the next shot in sees less fouling.
A few things could all line up in the one cartridge and reduce pressure and that reduces velocity .

Cooled down between each round. powder weighed and dispenced with Chargemaster. Cleaned between each powder charge. Using Lapua brass prepped on once fired cases. All bullets from the same lot. I plan to repeat the string again. This is a Savage F-Class rifle with a 30" bartlein Barrel that has 300 round count on it. Have you seen this also? This is my first and i have been shooting and reloading for a very long time.
Thanks, SEMPER FI ..... SARGESNIPER

 

[Bullet bumper]

I don't think it's that productive to repeat the one string of the different powder loads against eachother.
I would test a string of each individual powder load to see which one has the lowest SD for that powder charge .
Then try other tuning steps on that . In the end the target is the best judge of group accuracy .
Yes I have seen it before and all kinds of other wild results . Some related to bad chronies .
What do you mean , " cleaned between each powder charge ? " I don't use a Chargmaster I don't like them.

 

[LaHunter]

If I read the OP correctly, 5 rounds at each powder charge were used, so I assume the velocities posted are 5 shot averages.

1) depending on your chrono, that could very well be the answer. I have a Shooting Chrony Master Beta and I would not bet my life that the data is 100% accurate with this thing. I get some numbers from time to time that are crazy. Varying sun light can have an impact on mv data.

2) The velocity data is less than a 1.5% reduction from the lower to the higher powder charge. Again, the chrono data is not absolute for most chronos.

3) Maybe you could evaluate this load on a different day and compare mv data.

4) How far from your muzzle was the chrono set up. I try to set mine 14 to 15 ft from my muzzle to minimize the potential for muzzle blast error.

Just some thoughts.

Good Luck

 

[bootsking]

Do the loads again, but shoot one bullet per load in random order ; that is do not shoot all the 45.0 followed by all 45.5, etc. but mix them up. In this way the effect of chrono variability, barrel heating, etc will be randomized across the loads and the average will be more indicative of reality.

Also, how did the POI respond?

 

[benchracer]

I have seen this phenomenon using RL-17. Before my experiments with RL-17, I had been warned to watch for a DROP in velocity with increasing powder charge. Following that drop, the velocity will continue its upward trend for the next couple of powder charges, after that, velocity becomes erratic and pressure spikes start to occur.

Armed with that information, I was looking for the velocity dip to signify that I am reaching pressure limitations when I began load development with RL-17. First time out, sure enough, that phenomenon reared its head. Because of that, I work up until I see the velocity dip and treat the powder charge BEFORE the velocity dip as the max charge.

It would not surprise me if SUPERFORMANCE behaves similarly.

 

[Sargesniper]

If I read the OP correctly, 5 rounds at each powder charge were used, so I assume the velocities posted are 5 shot averages.

1) depending on your chrono, that could very well be the answer. I have a Shooting Chrony Master Beta and I would not bet my life that the data is 100% accurate with this thing. I get some numbers from time to time that are crazy. Varying sun light can have an impact on mv data.

2) The velocity data is less than a 1.5% reduction from the lower to the higher powder charge. Again, the chrono data is not absolute for most chronos.

3) Maybe you could evaluate this load on a different day and compare mv data.

4) How far from your muzzle was the chrono set up. I try to set mine 14 to 15 ft from my muzzle to minimize the potential for muzzle blast error.

Just some thoughts.

Good Luck

Yes, 5 shots for each load. The conditions were good for the chrono that day also. Setup was 15' from the muzzle. I check the chrono with another rifle with a load of known velocity. It is ok. Like i said from the start, i have never seen this up until now. Heard of it but first time to see it. Thanks for your response. SARGESNIPER

 

[Sargesniper]

I don't think it's that productive to repeat the one string of the different powder loads against eachother.
I would test a string of each individual powder load to see which one has the lowest SD for that powder charge .
Then try other tuning steps on that . In the end the target is the best judge of group accuracy .
Yes I have seen it before and all kinds of other wild results . Some related to bad chronies .
What do you mean , " cleaned between each powder charge ? " I don't use a Chargmaster I don't like them.

Should have said cleaned after each 5 shot string.
My chargemaster works flawlessly, would not want to go back to throwing and weighing. I have cut the time by half using the chargemaster. LOVE IT.
My chrono is old but it is accurate most dats. I check it with a load yhat is true in another rifle. I will repete the test again when i am able to get back to the range.
Thanks for the response ...SEMPER FI ........ SARGESNIPER

 

[Bullet bumper]

If I read the OP correctly, 5 rounds at each powder charge were used, so I assume the velocities posted are 5 shot averages.

1) depending on your chrono, that could very well be the answer. I have a Shooting Chrony Master Beta and I would not bet my life that the data is 100% accurate with this thing. I get some numbers from time to time that are crazy. Varying sun light can have an impact on mv data.

2) The velocity data is less than a 1.5% reduction from the lower to the higher powder charge. Again, the chrono data is not absolute for most chronos.

3) Maybe you could evaluate this load on a different day and compare mv data.

4) How far from your muzzle was the chrono set up. I try to set mine 14 to 15 ft from my muzzle to minimize the potential for muzzle blast error.

Just some thoughts.

Good Luck

You could be right , I was not sure what the '5 shots each " refered too . If he fired 5 of each powder load , then he could get an SD of the string of each powder load.

 

[Bullet bumper]

Should have said cleaned after each 5 shot string.
My chargemaster works flawlessly, would not want to go back to throwing and weighing. I have cut the time by half using the chargemaster. LOVE IT.
My chrono is old but it is accurate most dats. I check it with a load yhat is true in another rifle. I will repete the test again when i am able to get back to the range.
Thanks for the response ...SEMPER FI ........ SARGESNIPER

Ok got you . I don't throw and weigh . I set a measure and throw as many as I need. Once set the measure can just be got out clamped to the bench run the powder in , throw a few charges and return them to the hopper and I'm good to go . It's way faster than a charge master and I can do it on a tree stump in the bush if I need to. Many people like their chargemasters and I can respect that .

Two good powders you could try is Varget and H4350 both temp stable and less prone to load volume issues.
Harder to meter though due to being extruded powders but I don't have an issue with that .
Made in OZ by ADI (ADI names AR2208 & AR2209 ) I reckon Hodgdon H4350 should be good in a 260rem.
That is all I use in my 243W which is close to a 260 rem.

 

[milo-2]

I have seen this phenomenon using RL-17. Before my experiments with RL-17, I had been warned to watch for a DROP in velocity with increasing powder charge. Following that drop, the velocity will continue its upward trend for the next couple of powder charges, after that, velocity becomes erratic and pressure spikes start to occur.

Armed with that information, I was looking for the velocity dip to signify that I am reaching pressure limitations when I began load development with RL-17. First time out, sure enough, that phenomenon reared its head. Because of that, I work up until I see the velocity dip and treat the powder charge BEFORE the velocity dip as the max charge.

It would not surprise me if SUPERFORMANCE behaves similarly.

I'm totally behind what this guy wrote, though after the drop I've never seen the velocity come back up, but then I'll usually go home and pull loads with a higher charge.
To me 46.5gr is your max load, back it down some. You wont find any published data of 3113fps for a 120gr bullet.
Hodgdon's stated to be careful with this powder, and they don't list it as a 260 offering. I'm not saying it wont work, but at 46gr, IMHO, you're flirting with disaster.

 

[Sargesniper]

I'm totally behind what this guy wrote, though after the drop I've never seen the velocity come back up, but then I'll usually go home and pull loads with a higher charge.
To me 46.5gr is your max load, back it down some. You wont find any published data of 3113fps for a 120gr bullet.
Hodgdon's stated to be careful with this powder, and they don't list it as a 260 offering. I'm not saying it wont work, but at 46gr, IMHO, you're flirting with disaster.

The 6.5 Creedmoor is nearly identical to the 260 and the max load listed for it with Superformance and a 120-123 gr. bullet in Hornady's 8 th. edition lists it at 48.5 gr.
The listed velocity is 3000 FPS. from a 24 " barrel. My 260 barrel is 30". Some people claim that reloaded ammo is "flirting with disaster." I do not try to push my loads to the limit. I only used that cartridge as a referance point to start from. I chose a mid load to start with at 45.5 and worked up to 47.5 gr. So in conclusion,if the Creedmoor can ce loaded with it, why not the 260? By the way,46.5 - 47.0 gr. shoot bugholes with this powder. Thanks for you response and caution to me.
.. SEMPER FI ......SARGESNIPER

 

[Sargesniper]

Ok got you . I don't throw and weigh . I set a measure and throw as many as I need. Once set the measure can just be got out clamped to the bench run the powder in , throw a few charges and return them to the hopper and I'm good to go . It's way faster than a charge master and I can do it on a tree stump in the bush if I need to. Many people like their chargemasters and I can respect that .

Two good powders you could try is Varget and H4350 both temp stable and less prone to load volume issues.
Harder to meter though due to being extruded powders but I don't have an issue with that .
Made in OZ by ADI (ADI names AR2208 & AR2209 ) I reckon Hodgdon H4350 should be good in a 260rem.
That is all I use in my 243W which is close to a 260 rem.

Tried Varget and was not too happy with it. I do use H-4350 in the 260, but i wanted to try this powder out to see what it could do. I was surprised and pleased all in one. The velocity was good and the group was great. The H-4831 is also good with 139 gr.lapua's. I'm kind of off the 260 right now. Just got a Rem 700 in 308 that im working with,really a good shooter @ 300 yds. Shot it out in the Swamp a few weeks ago and it really shined with one load. Anyway i will get back to the 260 soon and try the test again.
Thanks for the input man.
SEMPER FI ............ SARGESNIPER