Range Report 77 smk velocity seems low
- Thread starter Jmccracken1214
- Start date
its surprisingly hard to get the 77gr smk to and over 2700fps and keep it accurate. aa2520 and N140 are the best powders ive found with 7.5 primers.
- Nov 3, 2010
- 10,242
- 22,126
23.7 grains of Ram Tac gets me 2715 fps from an 18" Larue. Mil primers
Since that is pushing Max load by the Hornady book, have you shot that and colder and warmer temperatures to see if you had pressure issues?
XBR will definitely give a bit better velocity with less powder compression at AR mag length.
That being said, once you get a couple hundred down the barrel I think you'll pick up a little velocity. And if the load is accurate, who really cares about 50-100fps? My Mk262 clone load is 23.5gr XBR which was initially 2670fps from an 18" BHW and eventually sped up to 2740fps. 23.8gr XBR matched or slightly exceeded Black Hills Mk262 white box but wasn't as accurate as the 23.5gr load.
I will say 24.0gr Varget under a 75/77 HPBT has been accurate in every rifle (bolt or semi) I've ever tried it in, albeit slower than a 5.56 pressure load...24.5gr was definitely faster but again less accurate.
That being said, once you get a couple hundred down the barrel I think you'll pick up a little velocity. And if the load is accurate, who really cares about 50-100fps? My Mk262 clone load is 23.5gr XBR which was initially 2670fps from an 18" BHW and eventually sped up to 2740fps. 23.8gr XBR matched or slightly exceeded Black Hills Mk262 white box but wasn't as accurate as the 23.5gr load.
I will say 24.0gr Varget under a 75/77 HPBT has been accurate in every rifle (bolt or semi) I've ever tried it in, albeit slower than a 5.56 pressure load...24.5gr was definitely faster but again less accurate.
Don't worry about velocity unless you need energy on target. If it shoots good leave it. You don't gain really anything by adding 50fps.
This is all 100% normal. Varget is accurate but mid-grade speeds in .223.
mk 262 clone loads are well documented, the better powders, however, are often un-obtanium.
I run the same load when I can’t get RL15. Roughly the same MV across three 18” Barrels with an AEM5. Completely normal.
CFE-223 gets me 2785 fps and .533 groups with the 77 SMK, Varget average was 2799 but .939 group. All said and done I settled on 23.5 Varget @2679 av. with a .675 group and 24 grn CFE 223 2637 av. with a .596 group, both loads shoot the same point of aim. New (2-300 rounds) White Oak 20" varmint .
H4895 is a great powder for heavy 556 loads, fast and accurate. Ramshot tac was a powder used in mk262, it's solid, handles temp changes and throws good on progressive press and uniflows.
Got a lead? I haven’t seen this for sale in over three years.
I shoot it all year, its the only load I use in this rifle. I have not had any issues but the weather here is never really at extreme ends of the spectrum. We average around 35 in the winter and 85 in the summer and I laddered up to this load during the summer.
Here’s XBR 8208 if you are near Reno Nv
I had a pound of staball match. I tried it today hoping it would shoot, so I could load these 223 on my Dillon. It won’t meter varget to save my life.
25gr of staball match and 77 smk at 2.26 was a winner.
Average 2650
ES: 17.9
SD: 5.9
5 shot group measures .46”
25gr of staball match and 77 smk at 2.26 was a winner.
Average 2650
ES: 17.9
SD: 5.9
5 shot group measures .46”
I’m going to try TAC it’s burn rate is all but the same as 8208 (my favorite for heavy .223 & .308) so much so that I would not tell anyone I used it. Haven’t seen a lb on the shelf in forever
