Extreme spread?

[plumbs7]

Just wandering as a rule if thumb ! How much extreme spread is tolerable ?
Also if you have excessive extreme spread is the round under charged , eg not enough pressure for the powder to burn consistently ?

Regards GS.

[Barry Davies]

Hi GS,


Rule of the thumb.
Short range --up to 600yds, you can get away with 25 f/s ES
Long range -- up to 1000 yds -- I try for 15 f/s ES and these values are for 10 shots, not 3 or 5.
A lot of factors govern ES -- Load variation --with good balance scales you should be able to keep load variation to 1/10 gn which equals about 7or 8 f/s for 2208. Good electronic scales will reduce this to 0.02 gn or about 2 f/s
So, generally it is not possible ( with good equipment ) to get excessive ES due to load variations.
Other ES variations come from -- neck tension, primers, case volume, projectile diameter variations, and probably the worst one of all is a badly fouled barrel.
There is a sweet load ( smallest ES ) for every combination of Barrel, case, projectile. etc and it's a matter of finding it by testing a variety of loads with a good quality chronograph. However, not always does the smallest ES produce the smallest group -- this is where tuning comes in.
No doubt others will have their own limits of acceptance.

[plumbs7]

Thanks Barry, my usual load is showing a little variation . Or my mag speed is a little to far away from the barrel and giving false data . Will load test on Monday and try a little hotter load . I weigh every round too.

Regards Graham.

[williada]

GS, Barry is on the money. His key word is tune. He could make a stick shoot. David.

[plumbs7]

I've upped the load to 46.5 and dropped the s/d from 13 to 7 and now 2990 Fps . I think 46.6 will be on the money! I think the barrel is wearing in and what worked with it when it was new is not working now eg a lower erratic pressure curve with my old load of 46.3 of 2208.

Much Better now ! GS .