Thread: Testing a conventional approach to load development

Originally Posted by STC

Barrel cooling does matter, as do plenty of other factors, how much they matter? that is not exactly known. Getting up and changing your shooting posture, has an impact. Parallax dialled out will minimize parallax, not eleminate it completely. fouling can change things too. All minor effects, that generally are not too important when dealing with general hunting precision requirements. But when you are looking at 0.25 or 0.5 moa differences, these minor influences do start to matter. Another thing is poi shift: since you fired all those shots into the same group you would not know if later 5 shot groups had a different poi, compared to earlier ones. So even if one of them was tighter to start with it would be hidden if any poi shift occured. Essentially any "signal" (if it is there) is hidden within other "noise", and thats why both of them show no significant difference.

Not saying you are a bad shot or anything (you clearly are not!). Essentially what you did is try to "prove" that for 2 charge weights, both of which already shot very well in your rifle (for general hunting purposes) there would not be a difference, (despite 3 shot groups indicating that there would be) by introducing a many other factors uf unknown impact into the system.

Your system here (rifle, loads, you) seems to give good (

Ok so there are several layers we're going to have to get through.


1. What is a sensible procedure for establishing the practical precision capability of a rifle system?
2. What is a sensible statistical test for comparing data when changes to the system are made, to detect whether or not the changes have resulted in a meaningful change in precision? (in this case the change to the system is a small difference in powder charge)
3. What is a sensible approach to load development?



Let's start with number 1.


What is your proposed approach for establishing the precision capacity of a rifle system? Defining rifle system in terms of the way that it is practically used - shooter, rifle, scope, and the specific ammunition.

What metric would you use? How precise would you expect your estimate of the precision capacity to be?

The stress-test of the way I have presented information is a useful peer-review - when it is conducted in a fashion that isn't useless snark (which will tend to generate useless snark in return)

Originally Posted by gimp

Is there any evidence of anyone ever experiencing a dangerous pressure issue when loading the correct powder within book loads?


It probably is wise to be conservative if you're shooting a vintage rifle or a cartridge that isn't a modern bottlenecked case.

Greetings @gimp,
I do remember one reported on the forum a few years back where a max load had blown up a rifle. From memory there were two contributing factors. First the data was for a much softer projectile and second the action, although considered strong, was 100 years old.
To me older data, especially where there the actual projectile is not listed, is always suspect. In other cases the speed of the powder has been changed for whatever reason. I believe that the max load in your work is one of these. The Hodgdon/ADI data lists a max load of 44.5 grains of AR2209 in the .260 with the 142 grain Sierra HPTBT for 2,735fps. It also lists 42.9 grains max of AR2209 with the similar 143 grain Hornady ELDX for 2,759 fps at slightly higher pressure. To me something is screwy here. The 44.5 grain load dates from 2,000 or earlier and AR2209 was sped up around 2,002 and the Hornady ELDX post dates that.
I discovered the speed change in 2019 when working with the 6.6x55. Fortunately I had enough of the old lots of AR2209 and my old chronograph records so I could document the speed change. Your 44.5 grain load should have produced a little over 2,600 fps in your shorter barrel but I suspect you may have got about 2,700 fps. There have been suggestions that AR2209 has been slowed slightly since I purchase the lot I tested in 2019 but still leaving it faster then the 2,000 stuff.
I have posted about this load and change previously so my apologies for any repetition.
In answer to your question above. Is it dangerous? Probably not but the pressure will likely be higher than the 60,000psi book max.
Regards Grandpamac.

Thank you. Your velocity guess is pretty good.


Observationally, there are many many people (including myself historically) loading over book max on this forum based on the "safe" approach of "working up" and observing pressure signs. Some of these loads/speeds posted are clearly well in excess of SAAMI max pressures for the respective cartridge.

I would hypothesise that of the 2 methods:

1. ignore book data and work up til you get "pressure signs"

or

2. stick below book max and work to a target velocity based on book max


#1 will result in more people running higher pressures than #2

Originally Posted by gimp

Is there any evidence of anyone ever experiencing a dangerous pressure issue when loading the correct powder within book loads?


It probably is wise to be conservative if you're shooting a vintage rifle or a cartridge that isn't a modern bottlenecked case.

In a nutshell, that’s the question I’m asking. Bearing in mind that there will be new reloaders reading this, it deserves clarification, including me.
Let’s assume, when you say modern bottleneck cartridges, we’re covering rifles from the last fifty years or so. Do we ignore chamber differences and assume, even if we load to max, that nothing untoward is going to happen? No real damage and maybe the worst that’s going to happen is a stuck bolt or just some brass issues? Is this acceptable now?

Sorry @gimp if I missed this, but did you clean your barrel at all during this process?

Originally Posted by caberslash

Sorry @gimp if I missed this, but did you clean your barrel at all during this process?

No, started with a fouled barrel (about 10rd down it) and did not clean during



Any degradation in precision due to fouling would be held equal across both loads as they were shot alternately.


The sequence of shots from each 20rd group didn't indicate any degradation of precision towards the last shots - the last 5 from each load went through the centre of the groups somewhere and were not the outliers.



Prior testing and other information indicates that barrel fouling isn't a practical issue for precision for hundreds of rounds

Originally Posted by Sidetrack

In a nutshell, that’s the question I’m asking. Bearing in mind that there will be new reloaders reading this, it deserves clarification, including me.
Let’s assume, when you say modern bottleneck cartridges, we’re covering rifles from the last fifty years or so. Do we ignore chamber differences and assume, even if we load to max, that nothing untoward is going to happen? No real damage and maybe the worst that’s going to happen is a stuck bolt or just some brass issues? Is this acceptable now?

Common sense still applies. If you find yourself experiencing pressure signs, reduce the load.

Originally Posted by Sidetrack

In a nutshell, that’s the question I’m asking. Bearing in mind that there will be new reloaders reading this, it deserves clarification, including me.
Let’s assume, when you say modern bottleneck cartridges, we’re covering rifles from the last fifty years or so. Do we ignore chamber differences and assume, even if we load to max, that nothing untoward is going to happen? No real damage and maybe the worst that’s going to happen is a stuck bolt or just some brass issues? Is this acceptable now?

Ignore this, can’t seem to edit. GPM raised the 260 load data issue and you’re gone part way to explaining your thinking. The chamber differences still bug me but if they’re still within tolerances can we assume we’re still ok? I ask this as I was getting bolt lift issues at the bottom end of powder charge when loading for my 270. It was my first handload so I was being conservative but it stuck with me, hence the questions.

I load 10 shots, each at an increment that is approximately 1% of the total weight (eg loads between 45 and 55 gr ill load at 0.5 etc) usually towards the top end of the load range then put them over the magneto, usually i get 2 flat spots in velocity, 1 at the low end 1 at then i load 5 in the middle of the faster flat spot if safe, and check it and that's the end of it. this is for long range ammo though and most of the time this works fine for me, only a couple of occasions ive had to tweak the load beyond this. and before i do anything i check max cbto, and then pick a jump, this always works except with berger VLD's that can be fussy at times. Im talking long range as in shooting deer out to say 800 yards or so with calibers like, 6.5cm. 270. 308. 300wm etc. not F class

for hunting out to say 200-300 yards (mostly under 200), i dont care just pick a cheap bullet, chuck a load in the middle of the load range through my powder dropper, load a few 100, and go hunt. my tikka groups these loads well under 1moa too, even if i mix bullets and bullet weights lol. honetly i have a mix of 150s and 180s in the mag sometimes lol and they shoot same place

For nice groups, setting your rifle up properly form a harmonic repeatability perspective will result in just about anything grouping well at 100 yards. ES is all i care about when load testing
Even my mossberg patriot, as as well as Mossberg ATR shot every bit as well as any of my expensive rifles after i set them up right.


Some general notes on what i do

Dry tumble
Anneal
FL size and deprime (bump shoulders 1 thou)
Trim
Chamfer
Deburr
Brush inside of necks
(i dont clean primer pockets)
Seat primers
load powder
Seat bullet

"pressure signs" on brass are very difficult to interpret consistently. Many things can create these signs - the hardness/quality of the brass, the sizing/headspace of the ammunition, etc. Some factory ammunition will show ejector marks or sticky bolt lift in some firearms. This .260 in this thread had sticky bolt lift and ejector marks with some rando factory 120gr Federal Fusion ammo I had that I used to get a rough zero.

While these signs may indicate a chamber pressure that is over SAAMI max, they also may not.

You can minimise your chances of experiencing problems by using quality brass, following a good reloading process (e.g. measuring and setting up your FL die for minimal shoulder bump) and thoroughly researching data before loading. Velocity is the best indicator of pressure - if you are getting more velocity than a reasonable estimate based on book max values corrected for your barrel length, you should reduce your load.


There is a reasonable practical safety margin between SAAMI max chamber pressure and the point at which brass will fail, and then higher again - the point at which it will be a problem. This doesn't mean we should eat into that safety margin, it just means that if you find yourself a little over SAAMI max due to variances, you won't die.

If you get indications of excessive pressure with any loading approach, reduce the load.

Well this is entirely another topic starting entirely.
I'll start by saying I think the methods of detecting pressure (or more accurately "over pressure") that we all read about are just about as reliable as the load development methods we read about..

I think knowing your rifle goes a long way

2 examples i have in my safe, my 270 Tikka is very slow and even at max book load i am well under max velocity (like 300fps), so my load for it is i think 4 gr over book max to get a decent velocity
but then i have a 308 tikka (this one has a 20" custom barrel with a tight chamber) and even with the "slow" 150gr sako softpoints i get nearly 2900fps (think 2880) which is probably on the top end of the pressures and with my 155gr handloads i think i max out at 45.8gr 2208 which is well below book max whereas my mates factory tikka i can go to 48gr 2208 and a 150 and its not causing issues.

Originally Posted by gimp

Thank you. Your velocity guess is pretty good.


Observationally, there are many many people (including myself historically) loading over book max on this forum based on the "safe" approach of "working up" and observing pressure signs. Some of these loads/speeds posted are clearly well in excess of SAAMI max pressures for the respective cartridge.

I would hypothesise that of the 2 methods:

1. ignore book data and work up til you get "pressure signs"

or

2. stick below book max and work to a target velocity based on book max


#1 will result in more people running higher pressures than #2

Greeting @gimp and all,
First I need to say that I have little faith in "pressure signs" in guessing pressure. I went well down the rabbit hole on this one at one stage but no longer. Most have been pretty well debunked so the answer to method 1 is no.
Charge, velocity and pressure are all quite linear within the normal pressure ranges so I mostly work up to velocity rather than charge weight. Data for most modern cartridges is pretty good with the odd exception and it is rare to find recorded velocities that vary much from the book data. For cartridges like the 6.5x55 and 6.5-06 data is all over the place and a bit more finesse is required. About 5 years ago I got serious about working up a decent load for my new Tikka 6.5x55. Possible velocity in a calibre increases at about 1/4 of case capacity so I spent some time measuring net case capacities and calculating a max velocity at normal pressure for the 129 grain SST by comparison with other cartridges including the .260.
So I used a calculated max velocity to work up to rather than the charge. Slightly different than your method 2. The .260 is loaded to a slightly lower pressure than some other modern cartridges so there is a little more headroom there than some other cartridges.
One thing I have discovered is that some heavy jacket cartridges like the LRAB push both velocity and pressure up from their thinner skinned brethren. In the 6.5-06 a change from the Hornady 129 grain Interlock to the Nosler 129 grain LRAB pushed velocity up by 100 fps, equivalent to adding around 2 grains of powder.
Regards Grandpamac.

After reading through the recent post my memory was triggered about some basic load development I did with my .223 .
I looked back through my photos and found this target .
If you look at the bottom left target/ group, it was a 5 shot group of one round of each powder charge .
The result wasn’t to far removed from the other powder charge specific groups and when you consider that it was a 5 shot group and the others were 3 then it kind of goes along with the whole “ noise “ thing of load development.