Acceptable Extreme Variations Factory Ammo

[Hogg0494]

Hi guys,shooting a 6.5 creedmoor with a 24” barrel,using factory Hornady 147 ELD match ammo.chrono it with a magneto speed and a labradar and am seeing extreme variation of 100 fps from one lot 97 from another lot and 89 from a 3rd lot
I dont reload but this seemed high to me
I called Hornady and they said its within spec.just wanted your input on this,as always,thanks and much appreciated

 

[308pirate]

Hi guys,shooting a 6.5 creedmoor with a 24” barrel,using factory Hornady 147 ELD match ammo.chrono it with a magneto speed and a labradar and am seeing extreme variation of 100 fps from one lot 97 from another lot and 89 from a 3rd lot
I dont reload but this seemed high to me
I called Hornady and they said its within spec.just wanted your input on this,as always,thanks and much appreciated

What sample size did you use?

How did you check calibration on both your labradar and magnetospeed?

 

[Frank Green]

Factory ammo is factory ammo. Even box match ammo. Seeing 60-70fps or even more can be the norm.

Also what barrel and the spec's it are made to on the bore and groove tolerances and what reamer the chamber was actually cut in the barrel...can and will effect pressures and effect velocities as well.

Later, Frank
Bartlein Barrels

 

[GIXXER2000]

I would think that factory match Ammo would be better than that. The only factory match ammo I have shot was in a Sig 716 and that was Fed GMM 175 and I think was about 25 to 30 FPS. I reload all my rifles so if my AVG FPS is worse than 15 and go back and look at my load. So 89 to 100 FPS seems off to me.

 

[Frank Green]

What sample size did you use?

How did you check calibration on both your labradar and magnetospeed?

Good call on both!

The larger sample size...the larger the deviation will be. Guaranteed!

Also clean barrel? Fouled barrel?

How many rounds on the barrel in between cleanings?

A lot of variables.

I've seen only 5 rounds fired thru the barrel and show a ES of 70fps. Not uncommon.

 

[308pirate]

Hi guys,shooting a 6.5 creedmoor with a 24” barrel,using factory Hornady 147 ELD match ammo.chrono it with a magneto speed and a labradar and am seeing extreme variation of 100 fps from one lot 97 from another lot and 89 from a 3rd lot
I dont reload but this seemed high to me
I called Hornady and they said its within spec.just wanted your input on this,as always,thanks and much appreciated

One more thing: what kind of accuracy did you get out of that ammo and what sample size did you use to arrive at that accuracy measurement?

 

[Hogg0494]

This is a tikka tac a1. All factory stock
Test was 10 five shot groups @ 100 yds.letting it cool 15 minutes between groups,rifle has 1,200 rounds on it. Fouled barrel(about 80 rds since cleaning)I only have a case of ammo all same lot that I tested.gun has shot this ammo since new,it tested most accurate from day 1
Gun shot 1/2” and better,now opened up to 1”-1.5”@100. Wondering if I just got a lot it doesnt like.wanted to see is 90-100 EV was acceptable before buying another couple boxes of a different lots
The labradar is my buddy’s so I know anything about it,I didnt know I could calibrate my magneto speed
This is my son’s rifle and I have checked all the basics and torques

 

[Hogg0494]

Ironically enough,I have been going through a similar issue with my rifle
Using the same ammo

 

[sniper79_98]

Does a new barrel say less than 40 rounds effect extreme spreads? I ask because I just shot 10 FGMM 168 grain and has an extreme spread of 100fps. Is this typical of Federal or of a new barrel? (18” proof)

 

[rustyinbend]

The only consistent thing about factory ammo ... is inconsistency. I've had match-grade ammo give me ES' of 100 ft/sec and SD's of 30+. I've also had it give me an ES of 35 and SD of 10-ish. And that was for the same brand and caliber (different lots). It's been all over the map for me, and that's ultimately why I took up handloading about 3 years ago.

 

[sniper79_98]

The only consistent thing about factory ammo ... is inconsistency. I've had match-grade ammo give me ES' of 100 ft/sec and SD's of 30+. I've also had it give me an ES of 35 and SD of 10-ish. And that was for the same brand and caliber (different lots). It's been all over the map for me, and that's ultimately why I took up handloading about 3 years ago.

I understand completely. The lot of hornady match for my 65 is like that with REALLY low ES&SD. Shooting and chrongraphing 308 with the ES of 100 and SD of 30+ is why I questioned the new barrel. It could be the FGMM. I’m going to shoot some Hornady match and see if it shoots the same in the 308 as it does in the 65.

 

[rustyinbend]

I understand completely. The lot of hornady match for my 65 is like that with REALLY low ES&SD. Shooting and chrongraphing 308 with the ES of 100 and SD of 30+ is why I questioned the new barrel. It could be the FGMM. I’m going to shoot some Hornady match and see if it shoots the same in the 308 as it does in the 65.

My Hornady 6.5-CM 147 gr ELD-M shoots ES's of around 50 and SD's in the low teens. That's close to as good as I've gotten with factory ammo. Hornady's American Gunner 6.5-CM 140's are way higher, but the interesting thing is that both group really well, and I've even used them in matches with good results, when I'm feeling too lazy to do a bunch of hand-loads. Lemme know what you discover on the new barrel with different factory loads.

 

[aagifford]

Similar to what I measured for factory Barnes match ammo. I’m pretty sure the powder charge is not weighed in any bulk factory ammo. Many years back I did a powder drop test and got variations of a grain or more on an RCBS powder measure with Varget. Other measures performed better as I recall. Anyway point is with varying charges the velocities jump around. Whereas my latest hand match load S-D is 8.

 

[Frank Green]

Does a new barrel say less than 40 rounds effect extreme spreads? I ask because I just shot 10 FGMM 168 grain and has an extreme spread of 100fps. Is this typical of Federal or of a new barrel? (18” proof)

Barrel I'll say can have an effect as well as the chamber spec in the actual barrel but there are other things to consider.

Also it would be neat to know your sample size you tested? 3 rounds fired? 5? 10? or 20 shot group thru the chronograph. I'll guarantee also that typically a bigger round count thru the chronograph you will get a bigger spread. I'll do 5 or 10 or 20 (20 seldom) 5 and 10 shots are the most common for me.

Virgin brass? If new box ammo the virgin brass will typically give you a bigger ES and SD numbers vs once fired brass etc...why? Even though the brass can look really nice...the first firing will blow out any imperfections internally in the case etc....