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Same weight bullet, different powder charge

10K views 60 replies 9 participants last post by  reynolds357 
#1 ·
I would like opinions from some of you very experienced reloaders on this.

Attached is reload data from Sierra and from Hornady. If you look at page 6 of the Sierra load data, they give a max powder charge of 27.5 grains of H335 for their 55 grain bullets and Hornady give a max charge of 23.2 grains of H335 for their 55 grain bullets.

I find it very hard to believe that there can be such a difference in the makeup of the Hornady vs Sierra bullets that it warrants a difference in powder of 4.2 grains. Especially when the Sierra and Hornady powder charges cover a wide range of bullets for each manufacturer.

It seems to me like Hornady is just being extremely conservative on their published load data.
 

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#52 · (Edited)
Did some shooting today and took careful measurements of the fired brass and took pictures of the primers along with a factory Winchester round. The factory primer is gold colored and my Federal 205M primers are silver.

The first picture is a 55 grain Vmax with 25.2 grains of H335 powder. This load is very accurate and is 2 grains above Hornady recommended max, but below Hogdon for 55 grain bullet.

The second picture is a 55 grain Vmax with 23.3 grains of H335 powder.

The third picture is a 50 grain Vmax with 25.6 grains of Benchmark, just below the Hornady maximum

There is no evidence of blowby around any of the primers, it's hard to tell but in my opinion the brass that had 25.2 grains of H335 might be a little flatter.

I also took measurements of all the brass in 3 locations and the widest point, all brass was within .002" at every measurement.

So in my opinion, none of these loads show overpressure signs.

What do you guys think?
 

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#53 ·
Measuring expansion is a difficult task and requires a Mic not a caliper to the .0001 not to the .001. I found this several years ago. might be worth a read if you are one to measure case expansion.




General Summary

1. Fire a Factory round.
2. Measure the “widest diameter” across the Pressure Ring with 0.0001” capable Micrometers.
3. Record this value as the Pressure Ring Expansion(PRE) on a Data Sheet
4. Calculate the PRE Average for the entire box of cartridges.
5. Record the PRE Average on the Data Sheet and on the box the cartridges came in.
6. This establishes the “Factory Standard Pressure Value” for this specific Lot of cases. This PRE Average will be used as the MAX Pressure Ring Expansion acceptable during Load Development.
7. Make a note that the cases have been “Fired 1 time” on the Data Sheet and the box.
8. Reload this Lot of cases with your first “Test Loads”.
9. Before firing, measure across the Case Head in one specific spot and record this value on “a new” Data Sheet.
10. After firing, re-measure the Case Head in the exact same spot and record.
11. Subtract the “before firing” dimension from the “after firing” dimension and record as the Case Head Expansion(CHE).
12. After firing, measure the PRE and record.
13. Repeat both CHE & PRE measurements for all Test Loads.
a. When Case Head Expansion reaches 0.0007” on your reloads, STOP.
b. When Pressure Ring Expansion reaches the same value as the “Factory Standard Pressure Value”, STOP.
14. If neither value in #13 is reached, note “Fired 2 times” on the Data Sheet and the box, and reload the cases with an incremental increase in the Powder. You must use the same Lot of Primers, the same Lot of Powder, the same Lot of Bullets and the same Bullet Seating Depth.
15. Continue the Testing until a 0.0007” Case Head Expansion is attained or the “Factory Standard Pressure Value” is duplicated.
16. You have now created a SAFE MAX Load for this Lot of cases.
17. This Load can be SAFELY duplicated in Lots from the same manufacturer where the weight of those cases is the same or less.
18. This SAFE MAX Load is for this one specific firearm ONLY!
19. Changing to a “New Lot” of any component used in the Load requires that you re-verify the CHE & PRE.


Details and Explanations

Case Head Expansion(CHE) can be “tricky” to read for a beginner. So can properly setting up a Sizing Die, determining the proper bullet Seating Depth or getting an Oehler M43 Strain Gauge properly attached to the chamber. With practice, and knowing how many shots have been through your cases, you can determine when to STOP increasing the Powder in your Load resulting in a SAFE MAX Load. This method will tell you for sure when you have reached an Un-SAFE Pressure. Yet, in my opinion, CHE is NOT AS RELIABLE an indicator as Pressure Ring Expansion(PRE). PRE is fairly straight forward and easier to quickly get a grasp on.

When taking the CHE & PRE measurements, you will use the Micrometer slightly different in order to obtain the most accurate values. When measuring CHE, you will use the ratchet feature on top of the Micrometer spindle to determine when the anvils are at the correct tension against the case head. When measuring PRE, you will set the Micrometers “just tight enough on the case to keep it from falling out from between the anvils”.

You measure CHE in one specific spot on the Case Head. CHE measurements must be taken before and after firing. I like to align the Micrometer with one of the numbers or letters found stamped into the case head. Turn the “ratchet” until it slips and read the Micrometer. Record that value for the “before firing” Case Head measurement on the Data Sheet. Lets say you measured 0.4121”. (Note: The numbers used throughout this paper are all fictional.) Fire the round and remeasure the case head in the same exact spot. Lets say you measured 0.4125”. Record the “after firing” measurement on the Data Sheet. The difference between the two measurements is the CHE. Subtract 0.4121” from 0.4125” and your CHE is 0.0004”.

When measuring PRE, you will be rotating the Pressure Ring on the case inside the Micrometer Anvils to locate the “widest diameter”. You must be careful not to deform the Pressure Ring by “forcing” it to turn between the anvils. Once you locate a tight spot, open the micrometers slightly and turn the case until you locate the “widest diameter”. For an example, lets say you get a measurement of 0.4772” at the widest diameter. Loosen the Micrometer to 0.4773” and see if the widest diameter on the Pressure Ring will “hang” between the anvils. If it won’t hang, record 0.4772” as your PRE measurement. You only measure PRE after the round has been fired and record that value. Loosening and tightening of the Micrometers does take a small bit of time to make sure you are recording a repeatable value. But, it goes real fast once you get used to it. You will get to the point that you can do it with one hand holding the case and the other hand adjusting the micrometer.


1. On Belted cases (7mmMag, 375H&H, etc.), CHE is measured across the Belt.
2. On Non-Belted cases (223Rem, 7mm-08, 30-06, etc.), CHE is measured just forward of the extraction groove (where the Belt would normally be located) with special “Thin Blade” Micrometers.
3. On Straight Wall cases (9mm, 357Mag, 444Mar, 45-70, etc.), CHE is measure just forward of the Rim with special “Thin Blade” Micrometers.
4. On a “fired” Belted case, PRE is measured across the “widest diameter” of the case body forward of the Belt.
5. On a “fired” Non-Belted case, PRE is measured across the widest diameter on the case body forward of the Extractor Groove.
6. On a “fired” Straight Wall case, PRE is measured across the widest diameter on the case body forward of the Rim.

The Pressure Ring is located in the same spot on the case body where Head Separations occur. If you have a Speer #12 Manual, look on page 72 and it is where the cases have split in the bottom two pictures.

In order to measure PRE, you will need to either P-FLR or FLR Bottle Neck style cases and FLR Straight Wall style cases between shots. Neck Sizing will not reform the case wall properly for these measurements. Once you know where the SAFE MAX Load level is located, then you can go to Neck Sizing if you so desire.

Adjusting a FLR Die to P-FLR is done by “slightly raising” the FLR Die higher in the press than normal. When adjusted to P-FLR properly, the bolt closes on an empty, length-trimmed case, with a slight bit of resistance. This indicates you have a crush fit between the case-head/case-shoulder and the bolt-face/chamber-shoulder. That ensures the longest possible case life, helps prevent case-head separations and increases the accuracy potential of your rifle/load combination. This is also referred to as “Zero Headspace”.

CHE measurements vary considerably on the very first firing of a new case. This is why you do not bother to measure them on the initial firing of the Factory rounds. If you desire to see the variance, just measure the factory rounds on the initial first firing. I do not recommend this for novice reloaders since it will create confusion for you as to why that is so. CHE measurements become more reliable for firings 2-5. Then CHE measurements become somewhat unreliable after 5-7 firings, depending on the strength of the previous Test Loads. This is due to “work-hardening” of the brass in the case head.

If you are using a Non-Belted or Straight Wall case, you will need to buy a set of “Thin Blade” Micrometers to measure CHE and the Thin Blade Micrometers can be expensive, $160 or so. But, I found a nice used set in a Pawn Shop that was asking $50. I got them for $25. On a Belted case you can measure CHE with regular $35-$45 Standard Anvil Micrometers.

PRE is measured using regular Micrometers whether the case is Belted, Non-Belted or Straight Wall. PRE measurements can be taken on the same cases 7-10 times, depending on the strength of the previous Test Loads. PRE is useable on ALL firearm cases and is the best method of the two. I encourage the use of both CHE & PRE so you end up with an additional set of Pressure Indicators, but a person can get by with PRE alone.

The Micrometers must be 0.0001” capable in order to be accurate enough for all of these measurements. A 0.001” capable Caliper is just not accurate enough and will mislead you if you try to use them, making all your Expansion Measurement data worthless and dangerous.
 
#55 · (Edited)
Wow, a lot of information there to digest. I honestly don't think I want to have to do all that, I just want to be reasonably sure my loads are safe.
Best way to do that is follow the manuals. Get as much data as you can for your choice powder and bullet weight, through out the high and the low and stay within the remaining data.

BTW, IMO your loads are safe and I would have no problem shooting them myself.
 
#57 ·
I have read this entire thread today and actually enjoyed it. I have been reloading for many years and have enjoyed it as well. But even though this info is interesting, I am starting to feel uncomfortable about reloading. Whatever you guys do, DON'T SAY YOU ARE USING LEE EQUIPMENT! I don't think my ole heart can take anymore. Thanks to everyone for sharing your expertise!
 
#58 · (Edited)
I have read this entire thread today and actually enjoyed it. I have been reloading for many years and have enjoyed it as well. But even though this info is interesting, I am starting to feel uncomfortable about reloading. Whatever you guys do, DON'T SAY YOU ARE USING LEE EQUIPMENT! I don't think my ole heart can take anymore. Thanks to everyone for sharing your expertise!
I have a Lyman press, .223 Lee die, .223 Redding Competition bullet seating die, RCBS powder measure, Lee 9mm dies, Lyman .357 dies, Hornady .32 ACP dies, RCBS 30-06 dies and Lyman tumbler. So I think I cover most of the manufactureres.

The Lee dies have never let me down. The Redding competition bullet seating die was expensive, but after trying one, I wouldn't be without it for reloading numerous different bullets for one caliber. I keep records on the setting for each bullet, very easy and convenient.

I'm glad you enjoyed the thread, there was good information here from much more experienced reloaders than myself.
 
#59 · (Edited)
Did some shooting today and took careful measurements of the fired brass and took pictures of the primers along with a factory Winchester round. The factory primer is gold colored and my Federal 205M primers are silver.

The first picture is a 55 grain Vmax with 25.2 grains of H335 powder. This load is very accurate and is 2 grains above Hornady recommended max, but below Hogdon for 55 grain bullet.

The second picture is a 55 grain Vmax with 23.3 grains of H335 powder.

The third picture is a 50 grain Vmax with 25.6 grains of Benchmark, just below the Hornady maximum

There is no evidence of blowby around any of the primers, it's hard to tell but in my opinion the brass that had 25.2 grains of H335 might be a little flatter.

I also took measurements of all the brass in 3 locations and the widest point, all brass was within .002" at every measurement.

So in my opinion, none of these loads show overpressure signs.

What do you guys think?
I would be perfectly happy with this if it were my loads and my rifle. I see nothing that would make me back the load down.
On the Hornaday case, I see what may be a faint extractor mark. To me, the primers look fine.
 
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