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#5996801 - 10/27/15 12:53 PM Factory Ammunition- What's really on the inside!!??
ChadTRG42 Offline
THF Trophy Hunter

Registered: 09/16/09
Posts: 9424
Loc: Lewisville, TX
As a custom ammunition mfg, I do a lot of custom load developments for rifles. Sometimes I get calls from hunters/shooters that have tried multiple factory ammunition brands/types to get their rifles dialed in. Sometimes, no matter what they feed it, it's not good enough. They want something better. A few weeks ago I got a similar call for 2 rifles. One a 7 STW and one a 257 Weatherby. The factory ammunition was very inconsistent and did not shoot well in either of these custom rifles. The customer asked me to pull the factory bullets, and use the high end brass to load for my ammo. No problem! Whenever I pull bullets on factory ammunition, I weigh their powder charges to see how (in)consistent it is. I am using a high end Sartorius digital scale accurate to .02 grains. Here is what I found!

7 STW- 140 grain Accubond factory ammo. I pulled 28 rounds and weighed the powder charges.
The average powder charge on 28 rounds was 80.08 grains. The high was 80.52 grains and the low was 79.74 grains. That's a .78 grain extreme spread.

257 Wby 110 grain AB factory ammo. I pulled 25 rounds and weighed each powder charge.
The average was 66.56 grains. The high was 67.24 and the low was 66.08. That's a 1.16 grain extreme spread on 25 rounds!

The 7 STW had a .78 grain powder extreme spread and the 257 Wby had a large 1.16 grain powder extreme spread. So, what does this high extreme spread mean? When loading precision ammunition to tune the ammunition to the rifle, you often load your test loads up in about .3 grain increments. For example, Load A may be 44.0 grains, load B may be 44.3 grains, Load C may be 44.6, Load D 44.9, and Load E 45.2. These 5 test loads have a 1.2 grain spread from start to finish. Within these A-E test loads, you can find a sweet spot where the rifle likes to shoot. Generally, a .3 grain increase in powder charge will increase the bullet velocity about 25-30 fps. So a full grain of powder will generally increase your bullet velocity about 90-100 fps. This .3 grain increment is small enough to see where the rifle wants to shoot well to find the sweet spot. If the factory 7 STW ammunition on 25+ rounds already has a .78 and the factory 257 Wby ammo has a 1.16 grain spread, that will not allow the rifle to stay within a given accuracy node. This will open up the groups and cause inconsistent shots. Plus, the .78 grain spread on the STW ammo will cause about 65-80 fps spread. The 1.16 grain powder difference on the 257 Wby ammo will cause about 96-120 fps spread. That's a lot!!!

Also, what I noticed on the 257 Wby ammo is a lot of charges were on the high side and on the low side. The average charge was 66.56 grains, but most of the powder charges were closer to the max and the min charges, not the average. There were not many close to the average charge. Also, when I have done these in the past, the smaller the opening (diameter of the round), the worse (or higher) the spread is on the powder charges. The 257 Wby held true to this also.

If you look at these 2 targets below, I am going up in .3 grain increments in powder charge with these test loads. In the first target, you can see a noticeable decrease in group size with Load C. This was a 1.032" group shot at 300 yards. The second target is a 243 Win. You can see the top right group about 1" at 300 yards, also. I like using these test targets, because it shows a perfect load work up with the normal signs of what the rifle likes when shooting. You can see some openness, then the groups start to string a little, then you find your sweet spot and the group tightens up. This sweet spot is what you load to. When your scales are accurate to .02 grains, that's accurate to 1 kernel of powder. When the powder charges have a difference of .78 and 1.16 grains, this alone will open up your groups and make for inconsistent ammo. When you pull the bullets and weigh the powder charges, you can see what's really on the inside!!!!



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#5996827 - 10/27/15 01:05 PM Re: Factory Ammunition- What's really on the inside!!?? [Re: ChadTRG42]
Gone to Texas Online   content
Veteran Tracker

Registered: 07/05/13
Posts: 2349
Loc: Hurst
Wow, great write up Chad!

Thanks for sharing.
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#5996865 - 10/27/15 01:22 PM Re: Factory Ammunition- What's really on the inside!!?? [Re: ChadTRG42]
Big Fitz Offline
Veteran Tracker

Registered: 12/06/09
Posts: 2008
Loc: McKinney, TX
I suspected there would be a greater variation than hand reloaders can control but that is far beyond what I would have thought. Thanks for the info, Chad.
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Originally Posted By: syncerus
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#5996871 - 10/27/15 01:24 PM Re: Factory Ammunition- What's really on the inside!!?? [Re: ChadTRG42]
603Country Offline
Extreme Tracker

Registered: 07/03/12
Posts: 4872
Loc: Central Texas
Thanks for the insight. I had no idea that factory ammo was that inconsistent. I wonder if the 'good stuff' like Federal premium or Black Hills or Nosler Premium has anywhere near that much powder variance.

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#5996876 - 10/27/15 01:27 PM Re: Factory Ammunition- What's really on the inside!!?? [Re: ChadTRG42]
ChadTRG42 Offline
THF Trophy Hunter

Registered: 09/16/09
Posts: 9424
Loc: Lewisville, TX
One of the companies you listed above is this ammo!!!
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#5997007 - 10/27/15 02:42 PM Re: Factory Ammunition- What's really on the inside!!?? [Re: ChadTRG42]
NewJeep Offline
THF Trophy Hunter

Registered: 11/11/07
Posts: 5319
Loc: Boerne, Tx
I am going to go out on a limb and say it was Nosler.
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#5997045 - 10/27/15 03:01 PM Re: Factory Ammunition- What's really on the inside!!?? [Re: ChadTRG42]
BOBO the Clown Offline
decoy

Registered: 04/19/07
Posts: 41102
Loc: Metroplex
I just want to add that first target is a factory rifle and the owner is a really cool dude.

Chad's ammo with out a doubt extremely consistent

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#5997257 - 10/27/15 04:54 PM Re: Factory Ammunition- What's really on the inside!!?? [Re: ChadTRG42]
colt45 Offline
THF Trophy Hunter

Registered: 08/19/06
Posts: 5390
Loc: bastrop county
good info
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#5997403 - 10/27/15 05:52 PM Re: Factory Ammunition- What's really on the inside!!?? [Re: ChadTRG42]
fast88 Offline
Tracker

Registered: 10/13/13
Posts: 534
Loc: Smithville TX
Great info Chad thanks.

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#5997463 - 10/27/15 06:22 PM Re: Factory Ammunition- What's really on the inside!!?? [Re: ChadTRG42]
boonee Offline
Veteran Tracker

Registered: 01/09/11
Posts: 2084
Loc: Mesquite
Chad, that is what I have found. I pulled down some Win." W-mart" 30-30, I found out of the 20 projectiles only 5 were 150gr most were lighter and 2 were 154. Powder weight was all over with only 5 were the same.
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#5997533 - 10/27/15 06:59 PM Re: Factory Ammunition- What's really on the inside!!?? [Re: ChadTRG42]
txtrophy85 Offline
THF Celebrity

Registered: 08/12/05
Posts: 22039
Great study!

Whst velocity are you getting with your loads with the .257 wby 110 grain bullet?
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Originally Posted By: Nogalus Prairie
I think the deer hunting shows and "Bro' Country" are going to be the downfall of this once-great nation.

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#5997564 - 10/27/15 07:16 PM Re: Factory Ammunition- What's really on the inside!!?? [Re: ChadTRG42]
RiverRider Offline
THF Trophy Hunter

Registered: 11/11/07
Posts: 6220
Loc: Wise Co.
You gotta wonder about all those articles that have been written about this rifle, or that, where they publish the results using a number of different factory loads. It's been a long time since I read a gun rag, and the way my memory performs as I get older I might not recall in a week...but sometimes factory ammo performs very well indeed. But I suspect that it might be learned that those particular cartridges were loaded with spherical powders if I were to dig up a bunch of these articles. It seems like a safe bet, anyway. I've never been a believer in trying to meter coarse extruded powders.
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Originally Posted By: Cleric
God I am hating caliber threads more and more

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#5997789 - 10/27/15 09:17 PM Re: Factory Ammunition- What's really on the inside!!?? [Re: ChadTRG42]
ChadTRG42 Offline
THF Trophy Hunter

Registered: 09/16/09
Posts: 9424
Loc: Lewisville, TX
RR, you got it right. I don't know why they use the extruded powders for metering by volume. You can not get a consistent weight doing that. There are plenty of slower burning spherical powders that will work well.
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www.DallasReloads.com
Type 01 and Type 06 FFL

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#5997791 - 10/27/15 09:17 PM Re: Factory Ammunition- What's really on the inside!!?? [Re: txtrophy85]
ChadTRG42 Offline
THF Trophy Hunter

Registered: 09/16/09
Posts: 9424
Loc: Lewisville, TX
Originally Posted By: txtrophy85
Great study!

Whst velocity are you getting with your loads with the .257 wby 110 grain bullet?


The top target is with a 257 Wby shooting the 115 grain Berger. The 110 will be moving a little faster, about 30-50 fps maybe.
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Type 01 and Type 06 FFL

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#5997835 - 10/27/15 09:33 PM Re: Factory Ammunition- What's really on the inside!!?? [Re: ChadTRG42]
kmon1 Online   content
junior

Registered: 09/27/06
Posts: 20293
Loc: Texas
Good write up Chad, agree with you and RR about extruded powders.


Something else it may be a different powder lot to lot with factory ammo.
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