Range Report  Is this excessive? chrono results

Peloton

Sergeant
Full Member
Minuteman
Jun 30, 2011
408
102
53
Western Washington
I don't reload...yet.

I've been religiously shooting .308 Federal 168 and 175 smk match and have been happy with the results.

This weekend I drug the chrono out again to check out some Black Hills Gold, 168 Hornady A-Max match.

I shot 5 rounds each of the Black Hills 168 and Federal 175 smk. The Federal was an average of 2583 fps with a spread of 19 fps between the fastest and slowest rounds. That's pretty consistent with what I've seen previously. The Black Hills had an average of 2539 fps, but what I found surprising was a spread of 108 fps between the fastest and slowest rounds. Is that difference normal with match grade factory ammo?

I'm pretty sure it's not acceptable. At 500yds that's a difference of .3 mil or 6.5 inches of drop.

Before I call Black Hills all irritated, I wanted to see if I'm being unreasonable or have unrealistic expectations.

Any input is greatly appreciated.
 

tnichols

Sergeant
Full Member
Minuteman
Jan 23, 2010
4,223
8,558
57
Morley IA
Re: Is this excessive? chrono results

I would make sure it's not a chrono problem on your end before you make a call to Jeff. Maybe shoot 5 more to verify. Last BH175Match I ran across the chrono had an extreme spread of 7, for 5 rounds. It's typically very consistant.
 

Peloton

Sergeant
Full Member
Minuteman
Jun 30, 2011
408
102
53
Western Washington
Re: Is this excessive? chrono results

That's good advice. I'll shoot another string and make sure I eliminate any other variables.

Thanks
 

Greg Langelius *

Resident Elder Fart
Full Member
Minuteman
Aug 10, 2001
8,897
4,953
AZ
Re: Is this excessive? chrono results

Speed anomalies with chronos are often the result of the chrono being too close to the muzzle and picking up interference from muzzle blast, which runs faster than the bullet. You'd think the gasses would be mostly transparent, but they actually create an optical effect much like very strong mirage, and chronos can pick this up. One symptom is this is erroneously high ES/SD velocity deviations

I would strongly consider placing the chrono at least ten feet ahead of the muzzle. Yes, that makes it a lot easier to accidentally shoot the chrono, which is why they warn us about such things.

Greg
 

Peloton

Sergeant
Full Member
Minuteman
Jun 30, 2011
408
102
53
Western Washington
Re: Is this excessive? chrono results

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Greg Langelius *</div><div class="ubbcode-body">Speed anomalies with chronos are often the result of the chrono being too close to the muzzle and picking up interference from muzzle blast, which runs faster than the bullet. You'd think the gasses would be mostly transparent, but they actually create an optical effect much like very strong mirage, and chronos can pick this up. One symptom is this is erroneously high ES/SD velocity deviations

I would strongly consider placing the chrono at least ten feet ahead of the muzzle. Yes, that makes it a lot easier to accidentally shoot the chrono, which is why they warn us about such things.

Greg </div></div>


This is one of the reasons I love this forum so much. I just learned something new. That may very well be my problem, my chrono was pretty close. I'll try again this weekend.

Thanks for the help.
 

tnichols

Sergeant
Full Member
Minuteman
Jan 23, 2010
4,223
8,558
57
Morley IA
Re: Is this excessive? chrono results

I've had muzzle blast issues as far back as 15ft with certain calibers. Don't be afraid to move back if you're shakin' the screens. Those little sensors can be very sensitive. What kind of chrono are you using?
 

gstaylorg

Gunny Sergeant
Full Member
Minuteman
Aug 24, 2010
1,866
4
San Diego, CA
Re: Is this excessive? chrono results

You're not alone in your observation of large ES values for Black Hills ammo. I have chrono'd numerous types of BH ammo, both in .223 and .308, side-by-side with FGMM. I have had a few occasions where the ES of the BH ammo avg. MV was 2X or 3X higher than the FGMM. This is through different rifles, using at least two different chronographs, so I'm inclined to doubt it's a chrono or setup issue. It's not an issue that happens with every box of ammo, so I don't know the underlying cause.
 

Peloton

Sergeant
Full Member
Minuteman
Jun 30, 2011
408
102
53
Western Washington
Re: Is this excessive? chrono results

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: tnichols</div><div class="ubbcode-body">I've had muzzle blast issues as far back as 15ft with certain calibers. Don't be afraid to move back if you're shakin' the screens. Those little sensors can be very sensitive. What kind of chrono are you using? </div></div>


I'm using a Shooting Chrony f1
 

timelinex

Gunny Sergeant
Full Member
Minuteman
May 7, 2011
1,378
29
Scottsdale,Az
Re: Is this excessive? chrono results

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Greg Langelius *</div><div class="ubbcode-body">Speed anomalies with chronos are often the result of the chrono being too close to the muzzle and picking up interference from muzzle blast, which runs faster than the bullet. You'd think the gasses would be mostly transparent, but they actually create an optical effect much like very strong mirage, and chronos can pick this up. One symptom is this is erroneously high ES/SD velocity deviations

I would strongly consider placing the chrono at least ten feet ahead of the muzzle. Yes, that makes it a lot easier to accidentally shoot the chrono, which is why they warn us about such things.

Greg </div></div>
+1

I usually put mine at 15ft. just pull the bolt out and make sure that you see nothing but daylight. As long as you do that, you will never shoot your chrono.
 

matt2143

Gunny Sergeant
Supporter
Full Member
Minuteman
  • Dec 4, 2009
    1,908
    70
    Northern, VA
    Re: Is this excessive? chrono results

    I know it is not Black Hills but I too experience extreme velocity changes. I am shooting M118LR all from the same lot. I have fired rounds through gas guns and bolt guns, suppressed and unsuppressed. I have also used two kinds of chronos and experience up to about 110 fps shift. most round stay within 60-70 fps but I still regularly see 100+ fps. I am just making brass so I can reload, have about 3k pieces of LC LR. I also saw this with M852 LC match (about 60 fps max spread) and M118 special ball (all over the damn place). I did pull about 300 rounds of special ball and reloaded 165 sierra game kings after re weighing powder charges and wound up with 2800 fps from a 24" tube and a variation of about 5 fps.
     

    B3dlam

    Sergeant
    Full Member
    Minuteman
    Jan 3, 2012
    754
    3
    Kodiak, AK
    Re: Is this excessive? chrono results

    Something else to keep in mind is to ensure you aren't heating up the gun when you are testing if you shot one ammo much slower then shot another afterwards much faster you would expect the second load to have a higher extreme spread as the gun is warming up as you shoot it.
     

    Greg Langelius *

    Resident Elder Fart
    Full Member
    Minuteman
    Aug 10, 2001
    8,897
    4,953
    AZ
    Re: Is this excessive? chrono results

    Pampering the system to skew the results one way or another is counterproductive. The testing is done in order to uncover the system's actual performance characteristics. Unless those characteristics reflect the system's intended usage, they are misleading.
     

    korykhunter

    Sergeant
    Full Member
    Minuteman
    Jan 24, 2013
    145
    0
    51
    Hector, MN
    Re: Is this excessive? chrono results

    Had good luck with Blackhills in 223, but I have seen some ammo that I couldn't hold under 2.5" at 100. Grabbed my chrono and found up to 270fps spread. Couldn't hardly believe it. This wasn't match grade but I expected a little better than that.
     

    Bob 964

    Sergeant
    Full Member
    Minuteman
    Feb 10, 2011
    374
    0
    Tallahassee, Florida
    Re: Is this excessive? chrono results

    Go to the Sniper's Hide home page. In the upper left-hand corner, click on "Featured". Scroll down until you see an article entitled "Easy Chronograph Set Up." This will help you get your chronograph set up properly so you will get more accurate and consistent readings.
     

    wadebrown

    Sergeant
    Full Member
    Minuteman
    Oct 18, 2008
    773
    94
    60
    Minnesota
    Re: Is this excessive? chrono results

    A few years back I shot a lot of BH 175 SMK match grade ammo when we were testing a wind measurement system. We chrono'ed each round fired using a commercial Oehler chrony we were shooting at 1,000 yards and each round was located on the target board and measured. I was seeing extreme spreads that were over 150 fps, the velocity differences were real as I would tell the spotters where to look vertically for the round based on the velocity that was recorded by the chrony.

    Given the change in vertical that correlated directly with the velocities measured by the chrony I strongly believe the spreads were real. Given choices like FGMM, SouthWest and others I would not use BH again.
     

    gvanhyning

    Sergeant
    Full Member
    Minuteman
    Re: Is this excessive? chrono results

    <div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: wwbrown</div><div class="ubbcode-body">A few years back I shot a lot of BH 175 SMK match grade ammo when we were testing a wind measurement system. We chrono'ed each round fired using a commercial Oehler chrony we were shooting at 1,000 yards and each round was located on the target board and measured. I was seeing extreme spreads that were over 150 fps, the velocity differences were real as I would tell the spotters where to look vertically for the round based on the velocity that was recorded by the chrony.

    Given the change in vertical that correlated directly with the velocities measured by the chrony I strongly believe the spreads were real. Given choices like FGMM, SouthWest and others I would not use BH again. </div></div>

    I tried Black Hills ONCE and was not happy. I'd stick to Federal Gold Medal Match, it's what the other company strive for with regard to factory match ammo.
     

    Graham

    Generalissimo
    Full Member
    Minuteman
    Oct 30, 2007
    49,811
    27
    Michigan
    Re: Is this excessive? chrono results

    <div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Peloton</div><div class="ubbcode-body">Before I call Black Hills all irritated, I wanted to see if I'm being unreasonable or have unrealistic expectations. Any input is greatly appreciated.</div></div>You never stated what barrel length you were using. Black Hills has had some slow lots. You can confirm whether it's a bad lot by shooting it: If the ammo doesn't hold MOA at 500, you've got a problem. If it groups well, don't worry about it.
     

    wadebrown

    Sergeant
    Full Member
    Minuteman
    Oct 18, 2008
    773
    94
    60
    Minnesota
    Re: Is this excessive? chrono results

    Graham,

    I do not see how the barrel length makes any difference for the original poster as he was talking about the spread in velocity not how fast it was.

    wade
     

    Greg Langelius *

    Resident Elder Fart
    Full Member
    Minuteman
    Aug 10, 2001
    8,897
    4,953
    AZ
    Re: Is this excessive? chrono results

    Two pages of posts and not one mention yet about comparative accuracy.

    Get this straight folks, the target is the only true arbiter of accuracy.

    Greg
     

    wadebrown

    Sergeant
    Full Member
    Minuteman
    Oct 18, 2008
    773
    94
    60
    Minnesota
    Re: Is this excessive? chrono results

    Greg,

    I agree with what you said about comparitive accuracy, but with velocity spreads over 100 fps your accuracy is going to be hurting at LR. The time of flights are too different with high velocity spreads it will kill your vertical and your wind calls.

    I do all my load testing by looking at what happens at the target at the range I will be shooting that load at. I mainly shoot F-class at 1,000 yards so that is where I do my load testing. The logistics of load testing at 1,000 yards are greater than at 100 yards but I think the results are worth it.

    wade