Load development ?

[MJR]

I have developed my loads by way of carefully increasing the powder charge until I have obtained good accuracy with that particular bullet. I am wondering if this is correct or am I missing something
Would it be better to slowly increase the charge until the onset of pressure signs are seen, then back of the charge and look for accuracy improvements by altering the seating depth
How do others approach this

 

[jack]

It is useful to establish where pressure signs are.

I loaded 5 rounds at minimum powder load recommended by Vit and loaded 5 rounds each at 0.5 grain increments upto the max.
Then I shot them on the range to establish which was the most accurate load.
I got a stiff bolt at the load 0.5 grain less than the max and fired no more.

Then I varied COL at the most accurate load.
Using increments from lands of 0.060", 0.090" and 0.120".
I had to start at 0.060" as the minimum length of bullet in the case would give me 0.040".
The most accurate was 0.090"

 

[MJR]

Sounds very similar to what I do although I have tended to stop when the nest .5g higher charge reduces accuracy. I will develop more loads.....

 

[Claret_Dabbler]

I have developed my loads by way of carefully increasing the powder charge until I have obtained good accuracy with that particular bullet. I am wondering if this is correct or am I missing something
Would it be better to slowly increase the charge until the onset of pressure signs are seen, then back of the charge and look for accuracy improvements by altering the seating depth
How do others approach this

There is a method called the "Audette Ladder" which does something similar to what you suggest. It seems quite long and convoluted compared the the normal method most of us use, but I suspect it is much more scientifically reliable.

Google it and you will get an extended explanation, I think you really need to shoot your test groups at 250-300m to get the best out of this.

There was a poster on one of the UK forums who had a similar method and it made a lot of sense.

The way he explained it, you worked up velocity over a chrono until you got what you wanted, or could safely achieve. His theory, and I found it plausible, was that you could best effect accuracy by tweaking when the bullet exited the muzzle by altering your OAL. I am not explaining this very well, but I tihnk it would work.

 

[manc-munsters]

A mix of the above for me.

I start loading at 10% less than max, and load in 0.5gn increments.

Once I find the most accurate load, I chrono it and make sure it is doing the velocity I need for that particular calibre/use

Then I experiment with OAL until I get the tightest group poss. If I want to get really anal (and I usually do!) I then load more ammunition at 0.1gn increments from 0.5 under the current charge, to 0.5gn over the current charge.

Long and convoluted method, but I enjoy the reloading side of shooting, and it works for me.

 

[ecoman]

You have probably read what Admin just posted.

OK. Simple signs.

First if you can, look at a used cartridge base from the rifle you are loading-for.
Look at the primer and observe how flattenned it is.

Does it fill right across the primer recess on the case ? Is it dead flat ? Sometimed factory ammo is filled with a generalised batch of powder which will do the job in the most utilitarian and cheapest manner. It will do the job but in some instances - especially in days of yore, the ammo 'killed at both ends', causing flinching and bad shooting.

The chances are that if you start a few grains lower than the advised top load and work your way up, you will; achieve two things.
The first is that you will most likely arrive at the most accurate loading for that cartridge in YOUR rifle.
Go beyond and the group opens up a bit and the recoil increases.
If the group remains good - examine the fired primer for pressure signs.
The second is that you'll possibly not even approach the pressure sign flatness on the fired primer which you observe on the factory[/b] filled case.

A nice rounded-at-the-corners primer which does not completely spread to fill the primer recess means a safe pressure.

If you achieve a primer which has burst back through at the firing pin dent, then you are 'way over the top.
This would most likely be accompanied by a very difficult bolt opening.

You'll find that totally flattenned primers often accompany a pretty firm recoil.

Some of the older Norma .270 were filled with a general utility powder which did the job but were a bit uncomfortable to shoot-with. They produced a substantial recoil, a well-flattenned primer but still did not reach the supposed 3000 fps..

Just get yourself a reliable reloading handbook, don't be disappointed at the reloading data as regards velocities, and enjoy the reloading experience.

Often the velocities advertised in the handbooks are less than you might have hoped-for, but I can tell you now that they are often superior in velocity than factory ammo.
They shoot smoother, have less felt recoil, are more accurate in grouping, and much like a fly fisherman tying a fly, you begin 'grassing' your beast at the loading bench in your home.

By the mail coming in it sounds like there are a few students of reloading out there who know their stuff. I confess that I never considered the seating depth of bullet to be a pressure factor in reloading - unless you seat it out too far and it pushes into the rifling lands so that it cannot freely begin it's travel.

Live and learn.

OH ! If you spill some powder, DON'T vacuum it up. Electric sparks and nitro just aint compatible with good house insurance.
Just a thought.

 

[MJR]

Ecoman I don't know what you are saying.
I am not asking if its sensible to exceed max loads, I have found my rifles tend to produce pressure signs slightly below published anyway. What I am asking is that if I find a sweet load say mid way through the powder charge scale is there a benefit to be found by trying to improve accuracy on the faster rounds which are still under max and showing no signs of pressure by experimenting with seating depth

 

[Muir]

Want a simple method to determine when maximum pressure is reached?

Get 10 factory cartridges for the bullet weight you wish. Fire them in your rifle. Measure across the head area (ahead of the web) with a micrometer that reads to the 1/10,000 inch and record the measurements. Average them.

Take your FL resized handloads and begin firing, recording the measurements of the case expansion. When they get to 1/2 thou of the recorded average, stop.

You must use consideration when and if you change brass makers, starting low and working up. You can tell how tolerant the new brass will be towards previous data by measuring the case capacity in H2O of the new brass and comparing it to your previous brass. If it's less, you will know that you must start low, indeed.

As to the .5 grain work up wisdom: What if the difference between minimum and maximum is only 2 grains?? ~Muir

 

[Dr Spin]

Forgive my ignorance but are you saying that measuring the factory cases in that way allows you to assess the pressure from the load so that you can replicate it in your homeload?

Although Factory loads are not necessarily using cartridges at maximum pressure?

Is the measurement an accurate way to assess pressure?

 

[MJR]

As to the .5 grain work up wisdom: What if the difference between minimum and maximum is only 2 grains?? ~Muir

Good point :!: Not used powders yet that give me that scenario but i'll watch out for it.
I have to date reused factory federal brass so I will measure some newly fired brass and compare to my reloads. Thanks for the input.

 

[Muir]

Forgive my ignorance but are you saying that measuring the factory cases in that way allows you to assess the pressure from the load so that you can replicate it in your homeload?

Although Factory loads are not necessarily using cartridges at maximum pressure?

Is the measurement an accurate way to assess pressure?

This method is no direct measurement of pressure. What it does is to measure relative pressure compared to the factory loadings which are generally loaded to maximum allowable pressure. When your maximum case expansion approaches factory you have reached your stopping point..~Muir

 

[Dr Spin]

Looking at the Nosler website they include a measurement in their loads called load density which can be as low as 70-80%. I'm not sure what they mean by that? I assume it has something to do with pressure?

I know a lot of reloaders load to higher speeds than factory as they consider that factory loads err on the side of caution. They then look for signs of overpressure on the cartridge case as they increase the powder charge.

Obviously higher speed does not always equate to better accuracy but I think everyone appreciates a flatter trajectory

 

[ruki]

load density

... means the percentage of available case capacity filled with powder.

I try to load towards 100%. however that can mean using slower powder, which can mean that in a shorter barrel rifle you get a more marked decrease in velocity.

in my 7mm08 with an 18.5 inch barrell there seems to be a magic burn rate for 120-130 gr powders that gives me near 100% density. all the powder burned before it leaves the muzzle and good velocities. This is powder like Imr 4895, re 15 and N140.

Opinion i that 100% density makes for a more consistant burn.

When i started on the reloading game i worked very hard to get my oal's right. at that time i was loading .30-06 with 150gr sierra gameking. i was ignorant to the amount of shank being gripped in the neck. One day whilst out stalking i noticed one of my rounds had a quite significant "bend". these rounds were no where near a maxer but were nice and accurate. I went home, consulted with my manuals and got the oal they suggested which was a lot less than mine. I ran all of the rounds back through the press and made them all shorter with plenty of shank in the neck (said the actress to the bishop)

I tried them for accuracy and found no discernable difference

ruki