I have a 1:10 18" Shilen barreled ar15 chambered in 6x45. The gun is plenty accurate with most everything I have tried from 55gr up to 100gr bullets. It's sweet spot is 65-80gr bullets. One thing I have noticed is the velocity on my 55gr loads is slow compared to my 70gr. I currently load a 55gr Nosler ballistic tip at around 2950 before pressure signs. My 70gr TNT load is just under 3100fps with no pressure signs. I can load out to 2.310 OAL. Im curious as to why my 70gr loads are 150fps faster and my 55gr loads just seem to stop speeding up. Is it simply a poor powder choice on my part? I have on hand, Xterminator, 2015, 2520, h335, Tac, IMR4198, 2495, IMR8208XBR, CFE 223, SW tactical rifle and N133. I use xterminator for the 55gr load and IMR8208XBR for the 70gr load. I use cci450 primers with the Xterminator and Federal Ar match for the IMR8208XBR. Out of those powders do you see one that stands out to work better for 55gr bullets in the 6x45? 2950fps is fast enough I am just wondering if I am leaving anything on the table since my 70gr loads are quicker. Thanks for the help.
6x45 55gr
- Thread starter LiveFire
- Start date
Based off the Hodgdon site, one would think you would be getting much faster speeds in the 55gr range. However, there test rifle had a 24" 1in9 twist. You will lose 25 to 50 fps per inch of barrel, but it still does not explain why the 70gr are faster. Xterminator powder seems to be the hottest powder you can use for the 55gr and the 70gr. Top end for the 55gr is 3388fps for 55gr and 3117fps for the 70gr.
I guess the question would be, are you really getting pressure signs with the 55gr? 2950 fps is well below the lowest posted speed for a 55gr.
I have a 16" gas gun that I load 70gr for and I'm getting just under 3000fps. Havent loaded anything lighter than that.
I guess the question would be, are you really getting pressure signs with the 55gr? 2950 fps is well below the lowest posted speed for a 55gr.
I have a 16" gas gun that I load 70gr for and I'm getting just under 3000fps. Havent loaded anything lighter than that.
That is a good question. Perhaps I am misreading my brass for pressure signs. I do not have any laying around I can get to to post a pic of at this moment. What I am seeing is a deep indentation of the ejector on the case. Primers are flatter in comparison to lower charges of the same powder and components.
Pick up a pound of A2200 if you want some speed from the 55's.
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