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Primers
Mar 2, 2017 13:04:56 GMT
via mobile
Post by sako75varminter on Mar 2, 2017 13:04:56 GMT
Not yet Dave....been a bit busy on the deer!
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Post by davet on Mar 2, 2017 13:18:46 GMT
Lucky bugger.....I have knackered my back......housebound for last 2 weeks!
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Post by davet on Jun 15, 2017 19:11:12 GMT
Have just tested CCI and MUROM large rifle primers side-by-side in identical conditions.
260 rem, lap brass, 46g of N560 Temp 65 -70f, Humidity 60%, DA 1200 FT
I fired 2 x 5 shot groups of each primer....both will group .5 moa.
Now for the differences....
1 The CCIs produced some awful ES results.....77 & 44 for the 2 groups. 2 The Muroms cut this by 50% ! 3 The CCIs showed 48fps MV difference on the averages of the 2 groups. 4 The Muroms showed 1 fps MV difference on averaged velocities of the two groups!
Given that each group showed MVs in the upper 2800fps range I was sutprised to find that the Muroms print .5 moa higher than the CCIs.....down to barrel harmonics I guess......the Murom groups were very consistent.
I am transfering to Muroms and cutting primer costs by about 2/3rds.
Rich H......if you read this I would like to add 3000 Muromsto my wishlist.
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Post by c18rch on Jun 22, 2017 9:17:19 GMT
What was the change in MV between the Murom and the CCI?
And done.
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Post by davet on Jun 22, 2017 9:53:08 GMT
Rich
Thats the odd thing.....average MV for 2 group CCI was @ 2860 ...Murom was 2874 but printed higher.
Have to say that CCI group 1 was 2842 fps whilst group 2 was 2890 fps so quite a discrepancy!
Murom groups were 2874 and 2873.
It was a calm day with a fair bit of mirage so the target may have appeared higher so leading me to POA higher....will need to recheck.
Although I only shot 2 groups of 5 for each primer type they were only spread across 20 minutes or so ...ie essentially the same conditions.
I have had faster mv shoot lower before in a 308....at that time I thought it might be exiting the barrel faster and at a lower point in the harmonic cycle...it just feels counter-intuitive!
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Post by davet on Jun 22, 2017 10:00:14 GMT
Rich
Having a brain-fart on mv numbers....trying again!
My confusion was that cci group 1 was only 2842 fps whilst the second was 2893 as stated but both printed to about same POI at 100 yards.
I got tunnel vision on group 2 CCI MV at 2893 whilst Muroms at 2874 printed higher.
In the final analysis and subject to further trials I think Muroms will show greater consistency.
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Post by mattnall on Jun 23, 2017 5:07:43 GMT
Does this all matter?
The CCI with the awful ES and the Murom with their outstandingly consistent ES still group <.5" according to the after action report above.
It would appear to me that there is something else that would equate to good consistent rounds other than ES as both large and small ES still manage to group the same. Even a huge spread in average MV gave very similar grouping to the much tighter MV spread. I sometimes think as reloaders we get too worried about SD, ES and MV.
Now a 2/3 saving on price would make the decision between two primers that give the same results where it matters, at the target, easy.
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Post by davet on Jun 23, 2017 7:56:24 GMT
It was the savings that was the main driver......anything else is pure bonus.......CCI prices have gone way too far North!
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Post by c18rch on Jun 23, 2017 9:39:15 GMT
Murom £29/1000 and more consistent CCI BR £85/1000
No brainer really.
Also, whilst ES might make no difference in groups at short range, it makes a big difference at extreme range (1000yds +). 77fps difference in velocity is a difference of 2.2moa at 1000yds, 5.2moa at 1500yds. That's a massive difference.
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Post by davet on Jun 23, 2017 11:40:52 GMT
Agreed....I prefer knowing that any misses are caused by me and not the kit.
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