Is this an extreme velocity spread?

[TwoNiner]

I just shot my 6.5 creedmoor Savage LRP 26" barrel for the first time today using Hornady 120gr a-max match ammunition. Using a digital chrony I had the following velocities recorded:

(Shots #1-7 were not recorded. Not sure why but my Chrony wasn't detecting them.)
#8 2898
#9 2930
#10 2904
#11 2976 (fastest)

(took a 20 minute barrel cool-down break)

#12 2949
#13 2962
#14 2886
#15 2917
#16 2879 (slowest)
#17 2886
#18 2886
#19 2936

Low: 2886 High: 2976 ES: 97fps

Is a spread of 90+fps normal for factory match ammo? Or perhaps this is because my rifle is brand new? I'm curious as to whether I should spend more $$ on this ammo or go straight to reloading (once components come in stock...who knows when). For what its worth I shot some lake city .223 ammo that only had a spread of 69fps. How much should I be able to narrow down my spread with handloading the 6.5 creedmoor?

 

[EL34]

I don't know if it is normal for factory ammo to have a ES that high (don't shoot much factory ammo), but my handloads for .308 is less than half that.

Went back and looked at the data for Radway Green Surplus .308, and it had an ES of 77.03, an ES of 90 fps sounds a bit on the high side to me. At least for premium factory stuff.

 

[TwoNiner]

I thought so as well. My #12 and #13 shots were on top of each other @ 100 yards and then #14 with the low velocity shot low-left about an inch and a half. Might have been me since I'm new to the rifle though.

 

[seanh]

That seems too much spread to me.

How far out was the chrony? What was the lighting conditions? Any wind conditions moving the chrony around?

 

[VKC]

Spread is too high assuming it is the same lot and the variables did not change, such as temperature.

 

[tipper]

Just picked up my 12LRP 6.5 creedmoor , don't think I'll be trying Hornady that is way off.
I reload so I'll work some up. Just put a 260 CBI on another Savage the first 5 rounds were off by what I would call alot SD-23.6 ES-54, next 5 SD-5.6 ES-12, next 5 SD-8 ES-21, next 5 SD-5.8 ES-14, last 5 SD-6.8 ES-14
I cleaned after every 5 rounds. I hope for the 12LRP to do that good.

 

[TwoNiner]

VCK,

Well come to think of it I put the chrony at 10 feet for shots #1-7 and it was not logging data so I moved it out an extra 2-3 feet and it began logging. I had the sunshades installed on the chrony. Wind and light conditions were the same the whole time (bright light, ~8-10mph wind), same temp and same ammo lot. There was a lot of mirage looking through my scope and it was hard to spot a couple of the hits on the 100y target with my Konus spotting scope at 20x on the cardboard target.

Tipper,

Why are you cleaning your rifle every 5 rounds?

 

[tipper]

New barrel, mybe you should try it. Don't clean that often after loads worked up.

 

[seanh]

Try this...set it closer to 10 yards and make sure you're sending the rounds through the same area of the chrony...that's to say, don't move the rifle around on the bench allowing for different trajectories passing through the screen area.

10mph winds sustained wouldn't do anything but if you were getting gusts that caused visible movement of the chrony, the possibility of erratic results might occur.

 

[Heman]

To answer your question yes that is a large Velocity spread, even if you look at shot to shot ES you still have rather large changes. Normally people strive for single didgit SD's and ES's of 20fps or less. Last year a friend of mine was shooting the Mk248Mod1 ammo at a NRA Long Range match and in talking with him its tollerances are rather wide based on velocity but this is becasue you have factory mass produced ammo trying to drop H1000 powder in it which we all know is not conduscive to accuracy. To answer your qustion you should be able to get ES to be less then 20fps and have single didgit SD's as this is what I have with my .260 Rem gas gun.

How did the rounds group? Reason I ask is I've quit using my Chronograph just for this reason you get nice numbers then have that one shot or two that throws the measurements out of whack and causes you to wonder. What caused me to stop doing this when I was working up loads for my .280 Rem the load I ended up going with shot the best on target but had the worst numbers. If the rounds are shooting MOA or less at range don't worry about it.

 

[Sniper260]

Yep. Don't worry about SD if they grouped less than an inch I'd say... your shooting factory ammo... what do you expect? And 1-9 SD is tits... 10-20 is usually fine for my guns, after 20 fps SD I know it was me jacking something up when I reloaded.

 

[6brshooter]

In the 12 or so match barrels that i own (Krieger,bartlien, LW,rock,shilen,criterion) each one showed slower clean bore velocity compared to fouled bore. Typically 35-100 fps difference, my bartlien 6 br is the worst offender, right at 100 fps difference on clean/fouled barrel spread now after they have a rd or two down them es usually hovers in the mid teens and SD in the mid single digits. Tipper u got a special factory barrel if ur cleaning every5 shots and ur es is in the teens.

 

[6brshooter]

Sorry tipper, i reread ur post. It was the criterion that did that. My 2 criterion barrels show low spread on the clean/dirty velocity. My 6 br 1-8 is fast, 105 hybrids@2910. 20 shot string averaged 2910, ES 13.6 SD of 3.xx. Piled all 20 rds into a .422" group prone. My other cdi is a remage 243, 107 smk@3170, 24" barrel. OP, that spread is big, in my lrp 6.5cm factory140 shot great. Never tried the 120 load, and don't remember chrony data of the 140 factory stuff. If u handloads try 41.0, 42.0&42.4 h4350 under 140 amax, these charges have shot great for me and a large number of other 6.5cm shooters.

 

[TwoNiner]

My groups weren't that great, about 1.25-1.5 MOA. I'm new to this rifle setup so I think it was my fault. I'm pretty new to prone shooting and was wiggling the rifle around between shot to shot. I think next time I will try the bench with the chrony on a tripod for the most accurate results and then work my way down onto the dirt.

Right now I'm just trying to nail down what I should be reaching for in terms of ES and shot to shot SD and your guys responses have really helped out.

 

[6brshooter]

The smaller the es and sd the less vertical u will have at long range. I have a shilen 6.5cm and it is normally around 23 ish es and 11 SD it will show practically no vertical at 1k. Big ES &SD do not have a effect on short range accuracy I shot with a well known shortline br competitor and his most consistently accurate 22ppc load had 89fps ES. When i work up a load i look for accuracy at 100, then run it across a chrony for low ES&SD, if i find a load that does both then 9 times out of 10 it will be good at extended ranges.

 

[40xs]

I have an older Ohler 33 chrono. I've found that I have to make sure all my rounds go across the window close to the same place. Also, I have to place the computer box so that the muzzle blast does not affect the reading. Other than this I can only guess that your rounds are not that consistent. Considering that factory rounds are still made through automation and not individually measured like reloads.

 

[tylerw02]

My load has a double digit SD and ES is around 50 fps, but at 600 I get less than 3" of vertical. My velocity shows to be 2790 fps when I tried it for the first 50 rounds, but Ballistic AE said I was at 2830 at the time. I think my chronograph is off. Yours may be too. Try the load at distance and see what happens. The bullet doesn't lie, but the chrony may. Chronographs are just a baseline and no real substitute for field data.

 

[VKC]

I think you may have partially answered your own question with the chrono variables. They can be sensitive. Let us know how it goes with eliminating those variables.

 

[GUNZ n AMMO]

have you tried using a different chronograph? Match loads sometimes have powder loads that are not consistent. I found out that it varies from 41.0 to 41.8 on a 140gr AMAX loads. I don't remember the lot number but after 300 rounds of those, I've handloading since...

 

[Lynn Jr]

Two Niner
When you chronograph a load consistency is very important.I don't shoot groups while I'm chronographing as its too hard to keep ones shots timed correctly trying to do two thins at once.I place my timer on the bench and shoot in nice even intervals.If you don't shoot in nice even intervals the cases will heat up differently and throw your readings off.On a large case like my 300 Ackley a round left in the chamber for an extra 30 seconds will show up as a very fast shot each and every time.
On my 6BR's and 6 Dashers the ES will be single digits or its time to change something.
In my experience your extreme spread will look exactly like an hour glass.As you increase your powder charge in nice 1 % increments of 0.4 grains for a 308 the extreme spread will start out widely spaced then as you come into an accuracy node it will shrink right down.If you keep on shooting it will open right back up and so will your groups.
If you plot it out this is very easy to see.
Once you have your powder charge optimized if the E.S. is still too large the first thing to do is to change primers.They have the second largest affect on your E.S. and are a very cheap tuning aid.
As mentioned earlier a clean barrel will ruin your numbers completely.
If your after truly extreme accuracy it is common to measure your empty cases volume using rubbing alcohol or water with a little bit of soap added to it so it doesn't mound up above the neck.You leave your spent primer in the case and weigh them.You then add your liquid and weigh them again putting all like cases into your match loads.
The pictures show me shooting over an Oehler 35 with the lights on to better capture the bullets as they fly over the proof channels and the rewards of producing very good reloads.