Hi there,
I started a very expensive Grendel project in Germany, see this thread for details:
My first 6.5mm Grendel Project - after 3 .223 Rem AR-15s
The rifle is built up and in testing the last weeks and I am facing accuracy problems, with Hornady factory ammunition as well as with reloaded ammunition. We tried different loads with VV N140 as well as XBR 8208, CFE223, IMR4895,...we are only using the finest reloading equimpent and components like Lapua Scenar 123 gr, Hornady 123 A-MAX and 123 & 120 gr Sierra MK bullets. The results are rather dissapointing. The best group (100m / 5 rds) we were able to produce was about 28 mm / 1.10" but it seemed like a statistical error - the average group size of app. 30 different loads was about 44 mm / 1,732" for a 5 shot group.
I started to examine the gun carefully and excluded all uncertainties like scope, rail, trigger,...until I came to the chamber dimensions and the rotation free flight of my setup. I measured the max. C.O.A.L. with this tool: Hornady OAL Gauge and found out, that I am able to load a max. C.O.A.L. of about 61.18 mm / 2.408" (measured with a Sierra Matchking HPBT #1727).
I would like to know from you if this rotation free flight is normal for a Grendel chamber or rather unusual and resulting in loss of accuracy. What are your max. C.O.A.L.s measured with the mentioned tool and what precision are you able to produce with loads when you load a C.O.A.L. of about 57,4 mm / 2.260"?
Thanks for your help!
I started a very expensive Grendel project in Germany, see this thread for details:
My first 6.5mm Grendel Project - after 3 .223 Rem AR-15s
The rifle is built up and in testing the last weeks and I am facing accuracy problems, with Hornady factory ammunition as well as with reloaded ammunition. We tried different loads with VV N140 as well as XBR 8208, CFE223, IMR4895,...we are only using the finest reloading equimpent and components like Lapua Scenar 123 gr, Hornady 123 A-MAX and 123 & 120 gr Sierra MK bullets. The results are rather dissapointing. The best group (100m / 5 rds) we were able to produce was about 28 mm / 1.10" but it seemed like a statistical error - the average group size of app. 30 different loads was about 44 mm / 1,732" for a 5 shot group.
I started to examine the gun carefully and excluded all uncertainties like scope, rail, trigger,...until I came to the chamber dimensions and the rotation free flight of my setup. I measured the max. C.O.A.L. with this tool: Hornady OAL Gauge and found out, that I am able to load a max. C.O.A.L. of about 61.18 mm / 2.408" (measured with a Sierra Matchking HPBT #1727).
I would like to know from you if this rotation free flight is normal for a Grendel chamber or rather unusual and resulting in loss of accuracy. What are your max. C.O.A.L.s measured with the mentioned tool and what precision are you able to produce with loads when you load a C.O.A.L. of about 57,4 mm / 2.260"?
Thanks for your help!
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