Difference in load data.

[SC_Dave]

Bullet: Hornady .223 FMJ BT w/cannelure
Powder: Ramshot TAC

Data from Western's site.



Data From Hornady's Site:



I'm having trouble understanding why the drastic difference. Both show current data from the bullet and powder manufacturers respective site. Which should I go by? Advice appreciated.
David

 

[Todd NE WY]

Start with the data that has the lower start point and work up. You may or may not get to the published "max" from either data source with your gun and components. Data from different sources rarely matches up, one thing to look at that doesn't show in your post is their projected velocity with the different charge weights. Say if the expected velocity from 23.1 and 23.2 from the different sources is pretty close then the data actually matches up pretty well one just picked a lower starting point.

 

[243winxb]

Western lists 3 Hornady 55 gr bullet. Each a different load/pressure.

Look at Hornady chart 5 different bullets same generic *powder charge*. DIFFERENT BULLET = DIFFERENT PRESSURE.

 

[SC_Dave]

The Hornady bullet I'm using (should have mentioned in the OP) is the #2267. Westerns listing for HDY 55 Gr BT-FMJ is somewhat generic I assume????

 

[243winxb]

Bullet differences- bearing surface. Jacket thickness. Lead cores can be different lead alloys. Sierra has 4 different alloys.

Higher pressure comes fron long bearing surface, thick jackets, hard lead alloys. Some times bullet diameters, like 44 magnum bullets .429," .4295"& .430"

 

[edwardware]

Both datasets are correct; the error is your assumption that they should match.

Lab-to-lab, chamber-to-chamber, brass-to-brass, and batch-to-batch (powder and bullet) variations exist, and all that's before we get to your rifle, components, etc.. The datasets reflect results in a lab, on a day, in a chamber. . . none of which are yours.

You should start low-to-mid, and work up, while paying attention.

 

[243winxb]

generic

The powder charge is generic. Looks like 24.7 is for the Vmax.

Work up to westerns loading for the 55 gr fmjbt.

Post #2 gave good info.

 

[SC_Dave]

Post #2 gave good info.

Yes, it does makes sense. Thx.

 

[noylj]

The important thing is to start at the start load. I always start at the lowest start load I can find.
All data in a manual is ONLY really for THAT lot of bullets, that lot of cases, that lot of primers, and that lot of powder. You almost certainly have none of those same things.

 

[lordpaxman]

I'm having trouble understanding why the drastic difference.

As others have pointed out, there are different testing fixtures with different samples of components. I only see about a 5% variation on the max load, I don’t think that’s very drastic. Start with the lower loads and work your way up until you achieve your objective. Good luck!

 

[kmw1954]

On 9/820 I actually emailed Western powder to ask this question in ref. to TAC. I graciously received a response from them on 9/9/20 and was told the Hornady SP 2265 and 2266 were basically the same bullet and to use the SP SX ( 2260 ) data for all three bullets. So that is what I have done and hope this helps.

 

[Dudedog]

Western also lists 5.56 data for that bullet with TAC so I would not be to concerned that their 223 data is a bit higher than. Hornady.
MAX 5.56 charge is 27.3, so 1.1gr more for the Western.223 data than Hornady is not cause for major concern.
As mentioned, different lot of bullets/powder/primers, different day, different test barrel etc.

You are going to work up to MAX anyway and it is always possible either listed MAX charge is more than a MAX charge for you gun, lot of bullets etc,
If you are using it in a 5.56 chamber you should have more wiggle room on top. Note CIP comercial pressures is higher than SAAMI for this round.

Here is a snip of Sierras AR15 data (which is lower charges than their non AR15 data), just to give you another set of numbers