Equipment & Gear > Guns and Ammo
Ask RBros Thread
Jolten:
Reloading .308 using BLC2 powder, BR2 primers. 165gr HPBT Sierra GameKings loaded at 2.626COAL.
Powder weights from 40.5gr to 43.5. First 2 shots would touch. 3rd shot varied between 1/4 to 1inch apart from the first 2. And never straying in the same direction.
For example 40.5 gr first 2 shots would touch. 3rd would hit upper right 1/2 inch away from the first 2.
With 43.5 first 2 would touch. 3rd was 3/4 in lower left.
Any ideas on what would cause this? There was about a 3-4 min break between shots with 10min between groups. Using a Savage 10t with a 1-10 twist.
Angry Perch:
--- Quote from: rbros on August 23, 2016, 03:23:23 PM ---Midlength of the scope would give you an average. On a long action 30 MOA rail your talking about .042" of slope roughly in the length of the rail. Using the mid point of the scope would get you and average, but like I said, its not a huge bearing on impact whether you measure at the lug area or the eyepiece.
--- End quote ---
I think I can safely say that I know less about long range shooting than anyone. I'm a sight it in a couple inches high at 100, and don't shoot past 20 kind of guy. But I've always wondered what a "20 MOA rail" or "40 MOA rail" was. Is it actually slanted towards the muzzle so you have some built in elevation?
rbros:
--- Quote from: Jolten on August 23, 2016, 03:41:15 PM ---Reloading .308 using BLC2 powder, BR2 primers. 165gr HPBT Sierra GameKings loaded at 2.626COAL.
Powder weights from 40.5gr to 43.5. First 2 shots would touch. 3rd shot varied between 1/4 to 1inch apart from the first 2. And never straying in the same direction.
For example 40.5 gr first 2 shots would touch. 3rd would hit upper right 1/2 inch away from the first 2.
With 43.5 first 2 would touch. 3rd was 3/4 in lower left.
Any ideas on what would cause this? There was about a 3-4 min break between shots with 10min between groups. Using a Savage 10t with a 1-10 twist.
--- End quote ---
It could be a matter of cheekweld. You may be able to be consistent for a couple shots then you position changes. You might try shooting 3 shots in a row and not pick your head up of the rifle while working the bolt. Try to find a reference point on your face where it touches the stock and keep that position the same. Identical concept to an anchor point in archery.
I am leaning towards form since you are always getting two shots to touch and there is no consistency where the 3rd is going.
rbros:
--- Quote from: Angry Perch on August 23, 2016, 04:23:03 PM ---
--- Quote from: rbros on August 23, 2016, 03:23:23 PM ---Midlength of the scope would give you an average. On a long action 30 MOA rail your talking about .042" of slope roughly in the length of the rail. Using the mid point of the scope would get you and average, but like I said, its not a huge bearing on impact whether you measure at the lug area or the eyepiece.
--- End quote ---
I think I can safely say that I know less about long range shooting than anyone. I'm a sight it in a couple inches high at 100, and don't shoot past 20 kind of guy. But I've always wondered what a "20 MOA rail" or "40 MOA rail" was. Is it actually slanted towards the muzzle so you have some built in elevation?
--- End quote ---
A 20-40 MOA rail is actually taller in the rear and slopes down towards the muzzle. This allows your scope to have more upward travel in simple terms. Lets say your scope has 100 MOA of travel. With the cross hairs centered you may be 50 minutes of elevation travel left. By installing it on a 20MOA rail, you would now have 70 MOA of elevation travel available in the scope now. Hopefully that makes sense how I worded it.
brew:
really cool thread...good reading--thanks for the info
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