Velocity ES

R. Macleod & Son - The Best Hunting Companion
gixer1

gixer1

Well-Known Member
Supporter
I threw some 6.5 Creedmoor rounds through the chrono the other day and although these are shooting great…(cloverleafing) I was just curious why I was getting the spread of velocities I was.

It’s all the same type of brass and number of firings (3) and none have been very hot loads (circa 2750fps) in the previous firings.

The primers are the same, (CCI450’s), same powder charge (46gr of RS62) charges measured on a Chargemaster and I don’t load them unless it’s bang on the 46gr.

The ES was around 65fps across 10 rounds, 3 shot strings.

Barrel has had 25 rounds through it from new so could it just be bedding in?

Or, just out of curiosity I measured the OAL and OGIVE of 11 rounds I have remaining, does the below table seem like it would give any significant variance due to seating depth?

As I said - not overly fussy as so far it shoots as good as it could be at 100 yards, haven’t pushed it out any further yet as this was just initial setup, just curious where the variance is coming from.

How fussy are folks with seating depths?? I’ve never really been that fussy over two decimal places to be honest.

673B053D-8B4F-46DC-9BF0-AD4937B21B4C.webp
 
gixer1 said:
I threw some 6.5 Creedmoor rounds through the chrono the other day and although these are shooting great…(cloverleafing) I was just curious why I was getting the spread of velocities I was.

It’s all the same type of brass and number of firings (3) and none have been very hot loads (circa 2750fps) in the previous firings.

The primers are the same, (CCI450’s), same powder charge (46gr of RS62) charges measured on a Chargemaster and I don’t load them unless it’s bang on the 46gr.

The ES was around 65fps across 10 rounds, 3 shot strings.

Barrel has had 25 rounds through it from new so could it just be bedding in?

Or, just out of curiosity I measured the OAL and OGIVE of 11 rounds I have remaining, does the below table seem like it would give any significant variance due to seating depth?

As I said - not overly fussy as so far it shoots as good as it could be at 100 yards, haven’t pushed it out any further yet as this was just initial setup, just curious where the variance is coming from.

How fussy are folks with seating depths?? I’ve never really been that fussy over two decimal places to be honest.

View attachment 244090
Click to expand...
Try firing all ten rounds in cadence, not three shots clusters. ~Muir

(And it's shooting cloverleafs. You want to mess with What? Why? Stop measuring things.)
 
What barrel, bullet + jump & brass combo ? .46 Rs 62 ? @ 2750 , thats into the neck of my lapua cases on my ladder 43 Rs 62 runs 2794, 44.5 @ 2878 with the 140g bullets.
At your round count barrel wouldnt be fully bedded in, prob speed up at around 150 rounds.
What dies, neck tension are you running, consistant neck tension critical to a lower es.
 
If your rifle shoots tight groups reliably then whatever you are doing works, so keep doing it. I don't use a chronograph or weigh individual charges of powder - I just use an elderly RCBS Uniflow dropper that is rather erratic. Some cases are full with no rattle of powder, others rattle even though the setting on the Uniflow is the same. But it works as the cartridges group tightly.
 
buddy.223 said:
What barrel, bullet + jump & brass combo ? .46 Rs 62 ? @ 2750 , thats into the neck of my lapua cases on my ladder 43 Rs 62 runs 2794, 44.5 @ 2878 with the 140g bullets.
At your round count barrel wouldnt be fully bedded in, prob speed up at around 150 rounds.
What dies, neck tension are you running, consistant neck tension critical to a lower es.
Click to expand...
Bullet is 140gr Sierra SBT’s, no idea on the jump as haven’t measured it yet. Lee dies, no idea on neck tension.

Not sure what you mean on the 43 vs 46 part of your post.
 
If you want the neck tension measurement, simply measure the expander. It's the last thing to size the brass .

Personally, I found RS62 seemed to work better for me using milder primers . That was in 243 .

Looks as though your seating variation is due to bullet variations .
 
If you want to reduce it you could try changing charge weight slightly (both up and down) as you may not have identified the centre of the velocity node, and try a different primer. Otherwise anneal your cases, trim to length and smear a touch of imperial wax on a Q tip inside the case neck before bullet seating. It wouldn’t hurt (much) to measure your case neck thickness, uniform if necessary and deburr flash holes and cut the primer pockets to a uniform dimension. Then you just need to weight sort them! What make of brass are you using?
 
If you really want maximise your rigs potential i d invest in a quality die set, the lee s tend to oversize the necks and when the sizing button is puled back through can leave inconsistancies in the shoulder neck area, in relation to the seating depth it makes more sence to determine that where the ogive of your chosen bullet toùches the barrel lands, selecting its prefered jump from there - in the region of 10 - 40 thou i d say for the game kings.
In relation to Rs 62 powder weight charges i conducted a simple speed test from 42.g up to 44.5 g to determine an accuracy node ie where the speed levels out as the load increases. I setteled on 43.5 grains at a speed 2820 fps. I was surprised at your 46g only getting 2750 fps.

The creed is an accurate forgiving round, i found it hard to get a bullet powder combo that wouldnt shoot, ive shot 3 rounds of different weights 43.2, 43.4, 43.6 g into a ragged 1 hole group at 100m , the extra time and precision starts to show dividends the farther out you go, any reaso able load will do at a 100 yrds.
 
What is the goal?
If you are shooting groups at 600+metres that are unacceptable then by all means change things until the ES is closer to zero

If its sub 300m stalking just move on

Have you measured the tension when you seat the primers?
Also not relevant
 
srvet said:
deburr flash holes and cut the primer pockets to a uniform dimension. Then you just need to weight sort them!
Click to expand...

There is a pretty strong consensus now that this is a pointless exercise.

If you are 'uniforming' the primer pocket, where is your reference/datum line?

The extraction groove/rim or case head?

Even then, commericial tools that advertise this feature and actually cut into the pockets are not consistent enough.

I'd listen to Primal Rights regarding this, as he has developed tools to measure such variances and says just start out with good (Lapua, ADG, Alpha Munitions) brass.





'Improving' in such a way = ruined!

Plus weight sorting ≠ differentiating based on internal volume.
 
If you mean the barrel has only had 25 rounds down it, then you're barrel is breaking in. Check your load after you have a few (200) rds down the tube. Until then, you're chasing your tail trying to look at ES's on a new barrel.

Also, if this is a hunting rifle, and not being shot at long range, then ES's aren't nearly as important as some think.
 
As marine PMI rightly said , if your load is accurate at your all of you usual hunting distances leave it be , it’s only at extended and extreme distances that these small but important nuances have a dramatic effects.
 
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