load development group size or velocity spread

phishroy

phishroy

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ok, here is my load developing test conundrum.
i have been working up a load for a savage rifle chambered in 338 lapua.
the powder is H1000
primer is CCI large rifle
bullet is hornday hollow point boat tail 250 grain seated at 2.775 at ogive which is longer than what is indicated in several manuals and the hodgdon website but works well in the rifle.

started off by doing a ladder test at 300 meters., loaded at 1 grain increments from 85 to 95 grain and at 1/2 grain increments from 95.5 to 98 grain (98 grain being the max load listed at the hodgdon website).
had to stop my ladder testing at 96.5 grain due to extremely flattened primers and sticky bolt syndrome.
so i did not want to proceed above 96.5 grains.
during the ladders testing i noticed that 92 to 95 grain seemed to like one another and stayed close together.

so my next step was to try and load some rounds and do some 5 shot group testing and chrony my results.
i loaded 5 of each 89 grain to 96 grain at one grain increments.

i should mention that i was shooting in prone position with bipod and cool time between groups.
shot the groups at 300 meters.
the tightest group was with 93 grains of powder, about 2.5 inches at 300 but it also had the largest velocity spread, 68fps. average of 2951 fps
91 grains seemed to have the smallest velocity spread (25 fps) but the grouping was poor, about 5 inches. average velocity was 2890 fps
at 94 grains the group seemed to open up again but velocity spread was 26fps. average velocity 2979fps
95,96 grains groups opens up more and entire group dropped about 5 inches lower from my point of aim which made me really scratch my head???? velocity spread for 95 and 96 grains was 41fps (vel' 3008fps) and 42 (3045fps)

so here is my delima,
should i focus on the group spread, size and work around the 93 grain area or should i look at the tightest velocity spread and focus at the 91 grain area.
or maybe i should redo these groups altogether and scrap these results?
 
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2.5" at 300 is well under 1 MOA. Even off a relatively unstable bipod(compared to a proper rest), I'd stop and sight in. Accuracy is far more important than velocity.
Forget where a group lands. When you're working up a load you only shoot for group.
The OAL is considerably less than Hodgdon shows. .775" shorter. They show 3.550". That number of your's correct? If it's 3.775" I'd guess that's what your chamber give to close to the lands. Mind you, loading close to the lands is a load tweaking technique that usually gets done after you have a load. Don't change it though. Seems to work.
That H1000?
 
I would do the ladder test to 400 idealy 1000 yards. It will give better results
Or
I prefer the OCW test at 100 yards to find the area where my load is the more resilient.
After you should play with the jump\jam to fine tune

Also generaly the smallest and stable velocity spread will be you most accurate and resilient load.
 
For load development I'd look at the group size. I can't see how any given powder load would result in MV variance - if I'm wrong, please edumacate me.

In my view MV inconsistency would be driven by loading technique variances (e.g.neck tension, powder load, flas hole uniformity) or component variances (e.g. primer consistency, bullet dimensions). I seem to recall a test that showed that some brands of primers could produce MV variances of greater than 25 FPS. Differences in brands of primers showed up to 60 FPS differences.

Seems to me that in load development you/we are trying to find a chamber pressure/MV that allows the bullet to exit the barrel in the most forgiving (in terms of precision) position of the muzzle during the vibration cycle of the barrel. As such, the MV variances that are inevitable will have a lesser effect on POI.
 
In fact it is not vibration but the shock wave propagation from the chamber to the end of the barrel and then returning to the chamber.

And no it is not only a question of consistency in your measure and etc... It is a factor but not the only one.

An example when i have done my load for the 6.5 saum my best load was at 61 gr the one that have the less SD. This load is resilient form 60.8 to 62gr and the SD is consistent. Afther that , charge over or under this ''node'' have bad SD and ES.

Group size is irrelevant and a false indication during initial load development. Point of aim is what mather in a resilient load.
Group size can be easlly tune after the powder charge is find by just playing with the jump.
 
sunray said:
The OAL is considerably less than Hodgdon shows. .775" shorter. They show 3.550". That number of your's correct? If it's 3.775" I'd guess that's what your chamber give to close to the lands. Mind you, loading close to the lands is a load tweaking technique that usually gets done after you have a load. Don't change it though. Seems to work.
That H1000?
Click to expand...

not OAL but rather OAL to ogive,
i stopped measuring OAL due to frequent inconsistencies of bullets and have a set OAL to ogive using a ogive measuring tool.
yes, H1000 not H100, fixed it,
thank you
 
I'm not an expert but I would stick with best grouping load and as mentioned before double/triple check all processes of reloading for consistency. Consistency in reloading and components will bring ES down. If nothing else works try factory crimp die(my personal experience), it can really bring ES/SD numbers down.
 
using lapua brass with redding neck size bushing with 2 thou neck sizing for consistent neck tension. all brass was measured and weighed.
bullets did have some inconsistency in length of about +/- 8 thou to my surprise
each charge was electrically dispensed and weighed.
trying to keep consistency.

Keven9934, care to elaborate on what is a OCW test?
 
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