too much difference in load data between companies

dukecrab

dukecrab

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I have been reloading with my 300WSM with H4895 for almost a year; since I am using reduced load only so I was looking into Hodgdon's load data only......and there is no problem......

Now I begin to reload for my 243, looking into hot load now, and begin to compare load data in different companies and find there is huge difference:

let's take 80 GR 243 for example

in barnes's website, it listed as

barnes/80gr/ttsx H4350 min 41.5 gr, 3159 FPS / maximum 45.5 grs, 3398 FPS

http://www.barnesbullets.com/files/2014/11/243WinchesterWeb.pdf

while on Hodgon's website,
it list
Hdy / 80 gr / GMX H4350 Min 38.3 gr, 3045 FPS, / Max 40.7 gr, 3183 FPS


while I suppose 80 gr Hornady GMX is almost similar to 80 gr Barens TTSX, both all copper, pretty much the same, but the data is huge difference, with hodgon's maximum below Barnes' minumum !!!


or, we take a look at Hodgon's another one:

Barnes/85gr/ TSX
H4350 Min 37.3 gr, 2972 FPS, / Max 40.5gr, 3141 FPS

on Lee's 243 Die Set manual:
Barnes/85gr/X solid bullet ( I believe in Lee's language, Barnes 85gr X solid bullet = Barnes 85 gr TSX)
H4350 Min 42gr speed unknown / Max 45.5gr 3214FPS

I understand that 80 gr TTSX is different with 85 gr TSX, but , are they so much different that the powder are HUGE difference?

worried, if I am using H4350 on 80gr TTSX / 85gr TSX bullet, which one should I follow ?
:mad:
 
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you can not compare 2 different bullets ..... that is what your doing

the tipped tsx is a copper bullet , the gmx is made out of guilding metal and not pure copper .

the length and bearing surface of the 2 bullets will be different too , which has a direct impact on pressures and the amount and type of powder used .

also case capacity has a huge impact on case pressures and amount and type of powder used .

everyone creating load data is not going t o be using the same cases , and if they did there are still variations between batches .

then you have to consider how the chamber was cut and the length of the throat and the tightness of the barrel and even barrel length .


no one is going to have the exact same data because all the variables involved are not exactly the same ...
 
You have to understand why the data differs from manual to manual. Firstly, the different companies use different rifles, with different chamber and barrel dimensions. Secondly, they may use different brass or primers. Thirdly, they use different lots of components, even if the components are the same brand and model. Every one of these variables can change things, and the combination of several variances can result in very significant differences in the data.
 
Its funny I have the Speer #9 reloading manual dated 1974 sitting on the floor next to me and was just looking at the answer to your question.

The chapter I was just re-reading was "Why Ballisticians get Gray!"

The answer is simple, no two firearms are alike in their dimensions, the reloading components vary, etc. and nothing is written in stone.
Example, .223/5.56 cases can vary from a case capacity of 28.0 grains of H20 to 30.6 grains of H20 and cause over 6,000 psi variations in chamber pressure between cases.

Example my Savage .223 rifle with a 1 in 9 twist has a longer throat than both of my AR15 rifles and can be loaded "hotter" than any manual data. On top of this in the Lyman manual a universal receiver and a pressure test barrel at SAAMI "minimum" bore dimensions may be used. And this barrel will generate the highest chamber pressures. In other manuals a actual Remchester firearm will be used and it may have larger bore dimensions and lower chamber pressures.

Bottom line "ALL" reloading data is "ballpark" compared to "your" firearm and this is why they tell you to work up loads starting at the suggested starting load and work up.

I spent a lot of money on Quickload software only to find out to get "accurate" output data a chronograph is needed to calibrate Quickload by tweaking the burn rate of the powder until the Quickload velocity matches the chronograph. So without a chronograph Quickload is just "ballpark" data also and no better than the average book manual. Do not get me wrong Quickload is a great tool for reloading and spits out all kinds of great information. BUT as I said no two firearms are alike and ALL reloading data will vary.
 
Use as many sources as you can. That way you can figure out which data is more pertinent and figure out your starting load data accordingly.
 
One thing to note is that Lee doesn't produce their own data but just copy it from other sources.

My advice would be to pick one and chrony it. If you want to be cautious, use the lower one.

Things that can effect pressure:
-thicker or thinner cases
-hotness of primers (even lot to lot inconsistencies)
-powder burn rate (varies for the "same" powder lot-to-lot and with age)
-chamber dimensions (a minimum spec match chamber will produce quite a bit higher pressure than a loose cut military chamber)
-throat dimensions
-barrel diameter (a .308" barrel can range from .3065" to .310" or above)
-barrel condition
-bullet material hardness
-bullet bearing surface
-ambient pressure
-ambient temperature
-different sensing equipment
-differently calibrated equipment
-pressure measured at different points in the chamber/throat
-lawyers/liability precautions
-various other things I've forgotten or don't know about

I have a 308 that has stiff extractions a good deal under the max load in the most conservative manuals. It appears to have an exceptionally tight chamber which could be part of it. Every rifle is different including the rifle or universal receiver used in the laboratory testing to produce load data. That's why loads need to be worked up instead of just one load working for all firearms. A max published load might be above max pressure with a certain combination of components in a specific rifle. The max load could also produce well below max pressure with different components and/or in a different rifle (I've had this happen with surplus rifles with loose chambers and worn throats/bores).

Load some ammo, bring out a chronograph of known accuracy, and start shooting. If you don't have a chronograph just load and watch for stiff bolt lifts or sticky extractions (primers wont tell you much with any accuracy).
 
And don't forget to look at the other "variables" along with the powder charge.

Most state what brand of case and what primer they are using. That can make a significant difference from one brand to another.
 
Thanks.

I thought same weight of bullet , should have close range of same powder.....
I understand there are many variables.....
while with one's minimum above another's maximum ....

OK, I will just accept it....sticking to manufacture's manual..
 
I buy quality barrels in batches. All the barrels are from the same lot of steel, and were bored, reamed and rifled consecutively with the same equipment.

They then get chambered with the same reamer and installed on similar actions. Then I develop a load for each. Each rifle is different.

I have 3 such 308s, and the velocity (same ammo) varies 150 fps from the slowest to the fastest.

These are "identical" rifles.

So why should we be surprised that different labs, using different ammo and different rifles have different specs?

I bet every book says start with the START load, and work up. There is no guarantee that your rifle will handle the MAx load.

I once saw a rifle that would not handle START loads, we had to load down from there.
 
Yukoner89 said:
Were you ever able to determine why that particular rifle was doing that?

Thanks for the great posts btw Ganderite
Click to expand...

It was a M36 Swede. The bullets were 140 gr, which have a very long bearing surface, so if the bore or throat was a bit tight, pressures would elevate.

We verified that the load was fine in other rifles and that other loads were fine in this rifle, but the combo was a no go. Needed a hammer to pound the bolt open.
 
I've got rifles that only take the minimum loads but still have all kinds of speed and pressure. Others go past most manuals and may or may not make the targeted velocities. After finding the maximum load for your rifle you can usually find a manual somewhere that agrees with you, for all the good that does then.
 
cdill said:
I have always found that Lyman starting loads are consistently lighter than from those of other manuals - same bullet, primer, case etc.
Click to expand...

This is because Lyman uses a universal receiver and pressure test barrels with minimum chamber and bore dimensions. Meaning this type testing generates the highest chambers pressures and other manuals use actual firearms that can vary greatly in dimensions.

Below is Quickload data for the same 25 grain load of H335, the lowest pressure is from a Lake City military 5.56 case with 30.6 grains of H2O capacity.

308_zpsf81bb4cc.jpg


Below is a .223 case with 28.8 grains of H2O capacity

288_zps26698a67.jpg


You have 6,000 psi difference in chamber pressure by just changing cartridge cases.

I made these charts to help pick the 25 grain load of H335 using mixed brass for close range blasting ammo for my AR15 carbine and not go over 50,000 psi. Meaning a medium pressure practice load load that is easy on the brass.
 
Thanks for the insight bigedp51. And glad you joined us Canucks from Penn Sate!!! :)

Yes, that makes sense, and I now recall that Lyman pretty much uses universal receivers for all their test data except in a few cases and handgun loadings.

My father always liked to use their data for starting loads so he was certain they were on the light side to work up to a loading that he liked and was accurate before any signs of undue pressure showed up.

CD
 
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