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Re: Primer Test
Posted: Sun Dec 29, 2013 12:38 pm
by EagerNoSkill
Dangermouse wrote:Tim,
What deference are you looking at, at 1000yards, between your best primer and worst on this test?
That would help me understand the importance of this exersize.
DM
Remember this was done at 200 yards and I did NO wind adjustments - I was focussed on elevation.
The
BEST single group was :
Load 5 CCI-BR4
It gave a edge to edge measurement of 1.25 cm Elev =
0.235 moa
The WORST was Load 4 CCI Magnum at 46.6 which gave 3.6 cm Elevation =
0.677 moa
Shot at 1000 yards that would be a meaningful variation.
Remember that 1 moa at 1000 yards is 10.47 inches
At 1000 yards the elevation spread would be extrapolated to:
BEST load = 2.46 Inches and
WORTS = 5.42 inches
Re: Primer Selection and Load Validation Test
Posted: Sun Dec 29, 2013 12:43 pm
by Dangermouse
So potentially 10cm's at 1000 yards or 1" for every 100 yards?
What is that in score points from V bull out?
DM
Re: Primer Selection and Load Validation Test
Posted: Sun Dec 29, 2013 1:10 pm
by EagerNoSkill
Dangermouse wrote:So potentially 10cm's at 1000 yards or 1" for every 100 yards?
What is that in score points from V bull out?
DM
1 Moa at 1000 yards is 10.47 inches or 26.6 cm
The V bull gap to the edge of the 4 circle is 0.25 moa.
So missing the edge of V by just over 2.6 inches in Elevation will result in a drop point.
Again NOT a massive difference but in the course of a string 2 or 4 points gone to elevation.
Re: Primer Selection and Load Validation Test
Posted: Sun Dec 29, 2013 1:23 pm
by Dangermouse
Very interesting...
Re: Primer Selection and Load Validation Test
Posted: Sun Dec 29, 2013 1:29 pm
by EagerNoSkill
The accumulation of errors make it difficult to decide what variable is in play.
During a string if you can trust that your load gives consistent elevation that the variation is coming from :
1. wind/range and/or
2. changing pressure/temp and/or
3. user error
Otherwise you get distracted and chase your own tail and soon lose the plot on the winds / consistent body position etc.
Re: Primer Selection and Load Validation Test
Posted: Mon Dec 30, 2013 2:15 pm
by ovenpaa
Great post Tim, I have only just had the chance to read this through and it gives some interesting results. Do you have any specific views on LR versus SR primers in the .308?
Re: Primer Selection and Load Validation Test
Posted: Mon Dec 30, 2013 3:08 pm
by pe4king
Tim
On the subject of primers, do you still want to swap ?, I did PM you
Re: Primer Selection and Load Validation Test
Posted: Tue Dec 31, 2013 11:02 am
by Maggot
ovenpaa wrote:Great post Tim, I have only just had the chance to read this through and it gives some interesting results. Do you have any specific views on LR versus SR primers in the .308?
Butting in as I do.....
To be fair the CCIBR4 and Lapma brass is pretty widespread, the only downside is you are looking at about .6gr extra load to offset the smaller primer.
The Palma brass does tend to last and take a beating.
Pitty the suppliers seem fit to shove the prices through the roof!!
