Post by: adamR on September 23, 2024, 06:32:01 AM
Knight Ultralight 50 cal shooting approximately 105 grains (by volume) of 777 FFG. This gun has always shot very well, and I've been comfortable to 200 yards with it with open sights. This year I put a Leupold Freedom BDC RDS on it, mounted with a bedded Murphy Precision 10 moa rail. I've been pretty happy with it, shooting 1" groups at 100 yards.
Last weekend, I put an adapter on it so I could run my Spartan Precision ProHunt TAC bipod on it. My groups opened up a little, call it 3" but right around center; I assumed I was just having an off day. I averaged 1820 FPS with about a 40 FPS spread.
Yesterday, I decided I wanted to be more accurate with my loads. I measured a couple different loads by volume on an RCBS powder scale and determined that 88.3 grains by weight is pretty close to where I should be. That close, I went ahead and bumped it to 90, filling every tube with 90 grains by weight +/- .2 grains. I figured I would have a slight shift but wanted to see if more accurate measuring would help my groups at all.
Last night, my groups were awful. I'd bet I shot 6" groups, 6" right, and 8" high. My velocities averaged 1941 with my highest being 1990 FPS.
Some things to note, I felt like I noticed the end of my stock flexing more; maybe in my head, I don't know. I could press the stock and have it touch the barrel. Maybe it's always been like that, I just noticed it more with the bipod on there. When shooting last week, I was slightly down hill and this week was slightly uphill, also making me think it has something to do with the bipod. I also just bought a brand new container of 777 as the old one was pretty much empty.
Here's where I'm at...
- Maybe it's the bipod, I'll go back to shooting off my backpack. Could the stock making contact on the end of the barrel because of the bipod add velocity? If it was making contact, would the point of impact shift up, down, all around?
- Maybe it's the new powder. Is it possible that the new powder burns that much hotter?
- Maybe it's the extra powder, although that seems like huge speed changes for less than 2 grains of powder. Simple fix, I'll go back to my original powder amount.
- Is it the red dot? Did I already destroy this thing with the recoil?
I can't get out again until Friday and then deer opens the next day... I was feeling very confident until yesterday but that changed rather quickly. I'm going to start by getting rid of the bipod but, who knows, I may rip the red dot off by the end of the day as well. Just wondering if anyone else could throw some opinions in based off of the information. Thanks!
Post by: Karl Blanchard on September 23, 2024, 08:02:33 AM
Post by: Longfield1 on September 23, 2024, 08:33:40 AM
1. Any new flexing of the stock or anything should be checked first.
2.Take the bipod off and try with your accurately measured loads
A. If accurate again the bipod is the issue, if not go to step 3.
3. Put the bipod back on with your measured loads and take off the sight and use your irons.
A. If accurate again then its your sight. if not proceed to step 4,
4. Go back to the powder you were using when you were accurate at the grain you were previously using.
A. If accurate then its something to do with your powder charge. If not i'm out of ideas.
Good luck
Post by: fishngamereaper on September 23, 2024, 08:57:16 AM
Beyond that...ya process of elimination
You changed allot at once...go back to the basics and see what happens.
Post by: adamR on September 23, 2024, 07:25:34 PM
I measured out 10 tubes of 105 grains by volume of the new 777 powder; it averaged 89.075 grains by weight.
I then measured out 10 tubes of 105 grains by volume of my old powder container; it averaged 81.8625 grains by weight with weights ranging from 80.8 - 82.9 grains.
I'm guessing, as long as I pour 81.8 grains of the new powder, I'll return to the velocities and POI I am expecting even though my powder by volume will be quite different.
Post by: raydog on September 24, 2024, 12:53:25 PM
Hope you figure it out, that's always frustrating
Post by: adamR on September 24, 2024, 03:38:57 PM
When you put the adapter on for the spartan bipod, is it possible the screw is just a little longer than it should be, possibly coming close or contacting the barrel?
Hope you figure it out, that's always frustrating
It's hard to say. But, to rule it out, I just ripped the adapter off and put the sling stud back on. I don't have a ton of time to rule things out so a change like that was easy.
Post by: raydog on September 24, 2024, 07:00:58 PM
When you put the adapter on for the spartan bipod, is it possible the screw is just a little longer than it should be, possibly coming close or contacting the barrel?
Hope you figure it out, that's always frustrating
It's hard to say. But, to rule it out, I just ripped the adapter off and put the sling stud back on. I don't have a ton of time to rule things out so a change like that was easy.
Good luck, and keep us posted
Post by: adamR on September 27, 2024, 07:33:47 PM
Lesson learned and I will no longer measure by volume in the future.