Published “accuracy load”…

[orpington]

For example, the accuracy load for .32-40 in a Lyman manual is 20.0 gr IMR 4198 using a 170 gr jacketed Hornady bullet. I guess the question is is that accurate for the rifle used by Lyman or does that load tend to be the most accurate for most .32-40 rifles? So, having said that, I would tend to start out with various loads at or near to 20.0 gr of IMR 4198, or work my way up to 20.0 gr and beyond, as the maximum load is 22.0 grains.

Or, for any random .32-40 rifle, is any published load likely to be more accurate for a particular rifle, not as to numbered grains, but as to specific powder? So, is a published load using IMR3031, for example, likely to be more accurate for my specific rifle than a load using the same powder as the “accuracy load”? In this case, the powder used commercially for .32-40, according to the manual, was the same as the “accuracy load”, IMR4198, except the factory load is 18.8 grains.

Or, I guess my way of thinking is if the “accuracy load” and the factory load use IMP4198, it might be best to start with IMR4198 loads. Good idea or fallacy?

 

[AJC1]

It's just the load that shot best in their test nossler list the overall best and best for each powder.

 

[Bearded Phil]

Like AJC1 said, it's the best they got with their testing. Sometimes that's a test barrel, some times it's a specific firearm. Lyman will list what firearm or if it's a Univeral Receiver and the basic specs on the gun/barrel.

Starting with whichever powder the list as getting the "accuracy" load isn't a bad place to start if you have it on hand or are willing to buy it but that doesn't mean that other powders can't produce good loads. Depends on what you want from your load.

For example, if the test data shows the best grouping with IMR 4198 but it's at the bottom of the load ladder and you want more velocity a slower powder may be a better choice. Just depends on if you are willing to possibly sacrifice some accuracy for an increase of FPS.

Or if the "accuracy" load is a slower powder near the higher end of the load data and you want an easier shooting load for plinking that still groups well you will have to play with a different powder at a different charge.

Since Lyman and other books don't even list range, group size, shot amount it's kind of a crap shoot. I honestly don't pay much attention to the "accuracy" loads in manuals.

 

[AJC1]

Like AJC1 said, it's the best they got with their testing. Sometimes that's a test barrel, some times it's a specific firearm. Lyman will list what firearm or if it's a Univeral Receiver and the basic specs on the gun/barrel.

Starting with whichever powder the list as getting the "accuracy" load isn't a bad place to start if you have it on hand or are willing to buy it but that doesn't mean that other powders can't produce good loads. Depends on what you want from your load.

For example, if the test data shows the best grouping with IMR 4198 but it's at the bottom of the load ladder and you want more velocity a slower powder may be a better choice. Just depends on if you are willing to possibly sacrifice some accuracy for an increase of FPS.

Or if the "accuracy" load is a slower powder near the higher end of the load data and you want an easier shooting load for plinking that still groups well you will have to play with a different powder at a different charge.

Since Lyman and other books don't even list range, group size, shot amount it's kind of a crap shoot. I honestly don't pay much attention to the "accuracy" loads in manuals.

I definitely include the accuracy load in my testing because it doesn't cost me anything. The nossler data is good because you see where in the range it falls including load density and you can shop the accuracy load that matches your speed needs.

 

[Hooda Thunkit]

Generally the "accuracy load" explanation comes with some wording such as "best potential accuracy".
The company, when shooting the powders, are usually looking for pressure data. Accuracy data is not generally the goal.

Usually, the company ballisticians are looking at internal ballistics; what is going on inside the case.
In that scenario, the "accuracy load" is the one with the best internal ballistics. The lowest velocity spreads, or the best deviation numbers. In other words, the most consistent.

Most shooters will find that the loads with the most consistent numbers will be the most accurate. Many times the accuracy will not show up at closer range.

Having said all that, every barrel is different. Your results may not , and probably won't, match a different firearm.

 

[WVRJ]

Very much a relative term,but sometimes is a good place to start.I think consistent pressure and velocity are what they go by,but that doesn't always mean more accurate.

 

[orpington]

Responses provided are what I suspected, but I didn’t know for sure. Hence the question.

Downstairs to the reloading room to try some different powders.

 

[LiveLife]

Published “accuracy load”…

... I guess my way of thinking is if the “accuracy load” and the factory load use IMP4198, it might be best to start with IMR4198 loads. Good idea or fallacy?

Published "Accurate load" I think means bullet exited the muzzle closer to zero oscillation/barrel bore line during barrel vibration/harmonics/timing/whip.

As other members already posted, "published" accurate loads expressed apply to specific firearm/test barrel fixture used with components listed (Often with new brass) during testing to capture data for publication.

But unless you are duplicating all the reloading and shooting variables (Which is unlikely particularly if not using same and new brass, firearm, barrel, barrel twist rate, barrel length, etc.), due to reloading and shooting variables may not reproduce condition where bullet exiting the muzzle close to zero oscillation/barrel bore line.

Which means while we can reference the "published accurate" loads but we must still conduct our own powder work up and range tests to identify accuracy nodes (powder charges that produce barrel oscillation/whip at zero oscillation/barrel bore line) while keeping track of reloading variables (Headstamp, year/lot, internal case water volume, neck tension, etc.).

 

[Howa 9700]

Somewhere along the line, it finally dawned on me they never really say how accurate those accurate loads were. Nor any of the rest for that matter Only velocity and pressure. As measured by my Caldwell chrony, my velocities rarely match theirs either. Some are spot on, others not even close.

 

[gwpercle]

It was the most accurate load used in the rifle used by Lyman during testing ...
not an absolute "the most accurate load in every 32-40 ever made" ... if you have never reloaded 32-40 it gives you an idea of a place to start ... more for the novice than the experienced reloader .
Gary

 

[BWS]

The 4198's in the 18-20 grain range,with CAST in rifles ranging from hot 223 loads,all the way through heavy bullet '06's..... and pert near everything in between;

Is a very good bet it's gonna be at the top of the list for accuracy powders.

37g of Varget is another one of those spots with cast.