Has anybody done any cronagraphed testing to see if a mag primer gives you a little more speed I am running cci sm rifle, with 28 gr of ar comp under a 107 tmk getting 2728 out of a 24 inch bbl.just wondering if a cci sm rifle mag will give a few feet faster? thanks HORDE!
small rifle vs small rifle MAG
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There was a post on the forum that had results that the CCI 400's actually gave more velocity than the 450's. I have seen this happen as well with my 1-7 twist 6PPC, got about 35 fps more on average.
Unfortunately, the 400's are best suited for mild to medium pressure (40,000 to maybe 45,000? psi.) and I have had primer piercing twice or three times with powder still 2 or more grains under max listed. Your experience may vary, and I've had better luck with the Grendel than with 6ppc or 6 arc.
I would definitely stay with the 450's or other primers with the thicker, stouter cups if any were to be had.
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The deal for the 400's is that they have a thinner cup material. Most primer studies look not for any absolute speed advantage, but for relatively better/lower std deviations. I did some testing of that in a couple of my rifles a couple years ago (not grendel) and observed that one primer would usually give you better, tighter MV groupings than the others.
In grendel, I find slightly better bolt gun performance (or at least as good as) with the Federal 205M vice the cci450... which is a good thing b/c it spreads my usage out to incorporate the 205's I have on hand.
LA, I've followed your experiences with cci 400's and, while the 400 is better suited to milder pressures, how much Milder may be subject to discussion IMO. I have used them in the past pretty extensively in my 223 loads, both bolt and AR, and while not pushing any max's I'm pretty sure the pressures were above your 40-45Ksi range... so there might be a bit more ## they can handle... My guess (I wasn't measuring pressures at the time) is they should be ok up to maybe 50Ksi... but it's just a guesstimate. My ARs have not had any slam fires with 400's, but I have since shifted the 223's (AR) over to cci41's or 450's just to be on the safe side."Down the floor, out the door, Go Brandon Go!!!!!"
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Primers - Impact on Accuracy (ES & SD), Impact on Performance (velocity), and Compatibility (pressure).
I believe the following two articles will give you the information that you are looking for.
Laurie Holland did an in-depth review of primers (performance by type/brand). He is a frequent contributor on Accurate Shooter Forum.
In parts 1 and 2, I’ve got as far as listing the primers that are generally available in the UK and summarising their characteristics - in particular, cup thickness/strength. I’ve questioned the significance and role of the so-called ‘magnum’ type and worked up a 308 Win ‘Palma brass’ load to be used in the tests,…
James Calhoon did a nice study on Primers (pressure and cup thickness)
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Originally posted by grayfox View PostThe deal for the 400's is that they have a thinner cup material. Most primer studies look not for any absolute speed advantage, but for relatively better/lower std deviations. I did some testing of that in a couple of my rifles a couple years ago (not grendel) and observed that one primer would usually give you better, tighter MV groupings than the others.
In grendel, I find slightly better bolt gun performance (or at least as good as) with the Federal 205M vice the cci450... which is a good thing b/c it spreads my usage out to incorporate the 205's I have on hand.
LA, I've followed your experiences with cci 400's and, while the 400 is better suited to milder pressures, how much Milder may be subject to discussion IMO. I have used them in the past pretty extensively in my 223 loads, both bolt and AR, and while not pushing any max's I'm pretty sure the pressures were above your 40-45Ksi range... so there might be a bit more ## they can handle... My guess (I wasn't measuring pressures at the time) is they should be ok up to maybe 50Ksi... but it's just a guesstimate. My ARs have not had any slam fires with 400's, but I have since shifted the 223's (AR) over to cci41's or 450's just to be on the safe side.
I agree. It seems CCI 400's and the .223 has much fewer primer piercing issues than other calibers. It might be due the pressure curve or the smaller amount of powder or something like that. The firing pin shape and amount of protrusion could make a difference as to when a primer pops.
I should have stocked up on the 450's back in the good old days.
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Edit to the above post.
Mixed my group values.
Cci400 2870 fps 5 sd
Cci450 2933 fps 8 sd
2% increase in velocity.Last edited by Happy2Shoot; 04-01-2021, 06:56 PM.
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Originally posted by Lemonaid View PostI agree. It seems CCI 400's and the .223 has much fewer primer piercing issues than other calibers. It might be due the pressure curve or the smaller amount of powder or something like that. The firing pin shape and amount of protrusion could make a difference as to when a primer pops.
I should have stocked up on the 450's back in the good old days."Down the floor, out the door, Go Brandon Go!!!!!"
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