Rifle shooting high, out of adjustment.
- Thread starter Vet66
- Start date
RaySendero
New member
Best shims I ever made were cut from a beer can after I emptied it!
Snyper, there is one thing on externally adjusted scopes that has to be moved after each time the rifle fires whether or not an adustment has been made. If it's not moved the same way every time, the next shot will be off an amount up to a couple clicks or more.
I'm trying to find out how much you know about such scopes.
I'm trying to find out how much you know about such scopes.
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externally adjusted scopes that has to be moved after each time the rifle fires
Bart, For sure this has to be remembered with a Lyman for sure, fire....reset. There is no spring as on a Unertl, well, high power for sure, unless you want to crack your forehead every time. Eye relief is very short. LOL
Bart, For sure this has to be remembered with a Lyman for sure, fire....reset. There is no spring as on a Unertl, well, high power for sure, unless you want to crack your forehead every time. Eye relief is very short. LOL
All such scopes I've seen on high power rifles had their springs removed or set forward so they weren't used. Scopes were pulled back after each shot to the stop with either a left or right twist to reseat them repeatable in the adjustment flats. With only 2" or less of eye relief, such was life as they slid forward an inch or more as the rifle recoiled back under them.
No, resetting scopes doesn't tell one anything about changing base height. I didn't ask about that, did I?
Testing scope repeatability by shooting the rifle under it is a very poor way to see if its adjustments are exactly what they're claimed to be. A 1/8 unit per click claim needs a shooting system producing no worse than one-third that level (1/24th unit) of repeatable accuracy across 20 or more shots to do it.
How do you measure a scope's repeatability and/or movement per click across several clicks?
Testing scope repeatability by shooting the rifle under it is a very poor way to see if its adjustments are exactly what they're claimed to be. A 1/8 unit per click claim needs a shooting system producing no worse than one-third that level (1/24th unit) of repeatable accuracy across 20 or more shots to do it.
How do you measure a scope's repeatability and/or movement per click across several clicks?
Bart, I've been following this thread with great interest. I think that externally adjusted scopes are most accurate and, repeatable.
I use a collimator to check repeatability, much more accurate than the internal disk type. I suppose not everyone sees it that way. I'm on the same page as you.
Vet66, externally adjusted scopes were the way to tiny groups for several decades. Until Weaver Model T's (the first really good one) and a couple of other internally adjusted ones had equal repeatability a few decades ago.
The front base of the externally adjusted ones was typically on the barrel Whatever weight there was there, coupled with the way the scope vibrated in its mount, put external variables onto the barrel before the bullet left. Receiver mounted scopes didn't do that and the result was smaller benchrest few-shot group records as well as better long range centerfire rifle records. It was the better bullets made then that shot more accurate that let the most accurate rifles and ammo show the difference between the two types.
The only competition shooting records made in the 1970's that never been broken are the .22 rimfire 100 yard prone records shot with externally adjusted scopes. But that's because rimfire ammo made since the early 1980's has never been as accurate.
The best internally adjusted scopes these days are as repeatable as the old externally adjusted ones. Evenly spaced clicks on threaded adjustments with a spring loaded tube against them are easy to make repeatable if the sliding adjustment surfaces are smooth enough.
And yes, an optical collimator is by far the best way to check a scope's repeatability. Or clamp one in a vise focused on something at least 50 yards away so sharp focus can be attained. Look through them with a 7X monocular and you'll see 7 times more detail in each click's movement on the target. It's rediculous for one to think moving a 1/2 to 3/4 MOA few-shot group about a target can resolve 1/4 MOA click repeatability. How much human error is there? How is that measured?
The front base of the externally adjusted ones was typically on the barrel Whatever weight there was there, coupled with the way the scope vibrated in its mount, put external variables onto the barrel before the bullet left. Receiver mounted scopes didn't do that and the result was smaller benchrest few-shot group records as well as better long range centerfire rifle records. It was the better bullets made then that shot more accurate that let the most accurate rifles and ammo show the difference between the two types.
The only competition shooting records made in the 1970's that never been broken are the .22 rimfire 100 yard prone records shot with externally adjusted scopes. But that's because rimfire ammo made since the early 1980's has never been as accurate.
The best internally adjusted scopes these days are as repeatable as the old externally adjusted ones. Evenly spaced clicks on threaded adjustments with a spring loaded tube against them are easy to make repeatable if the sliding adjustment surfaces are smooth enough.
And yes, an optical collimator is by far the best way to check a scope's repeatability. Or clamp one in a vise focused on something at least 50 yards away so sharp focus can be attained. Look through them with a 7X monocular and you'll see 7 times more detail in each click's movement on the target. It's rediculous for one to think moving a 1/2 to 3/4 MOA few-shot group about a target can resolve 1/4 MOA click repeatability. How much human error is there? How is that measured?
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Rimmed cases like the .220 Swift can have separation at their pressure riing just like rimless ones do. It's usually caused by the full length sizing die set in the press too far down to size cases correctly for your rifle's chamber. That sets back the fired case shoulder too far and the next time its fired, the case body stretches forward. Repeated cycles of this thin the brass about 2/10ths inch in front of the rim from work hardening. It eventually cracks.
Solution is to take several fired cases, back the die up about 1/10th turn then full length size just one case case. Chamber that case and if the bolt does close easy on it, back the die up another 1/20th turn.
Then full length size another fired case. Test it for easy chambering in your rifle chamber.
If the bolt doesn't easily chamber on it, turn the die in 1/40th of a turn which is close to .002" difference in die height in the press, then skip to the next paragraph. Otherwise, turn the die counterclockwise and move it up 1/40th turn. and try again.
Then full length size another fired case. Test it for easy chambering in your rifle chamber. If it chambers easily, lock the ring on the die then leave it there. Repeat this die adjustment until a resized fired case just chambers easily.The die's now set to minimally set the fired case shoulder back.
One other way to make tiny but accurate adjustments to die position is the following:
http://s860.photobucket.com/user/jepp2/media/DieAdjustment-1.jpg.html
Print them on full size label paper then use the .002" one to stick on your sizing die's lock ring. Follow the directions to mark then adjust your die for precise settings.
Or buy an RCBS Precision Mic or Hornady LNL Case Gauge to measure your case headspace (head to shoulder reference) and adjust the die so fired cases are sized to set their shoulder back .002".
Solution is to take several fired cases, back the die up about 1/10th turn then full length size just one case case. Chamber that case and if the bolt does close easy on it, back the die up another 1/20th turn.
Then full length size another fired case. Test it for easy chambering in your rifle chamber.
If the bolt doesn't easily chamber on it, turn the die in 1/40th of a turn which is close to .002" difference in die height in the press, then skip to the next paragraph. Otherwise, turn the die counterclockwise and move it up 1/40th turn. and try again.
Then full length size another fired case. Test it for easy chambering in your rifle chamber. If it chambers easily, lock the ring on the die then leave it there. Repeat this die adjustment until a resized fired case just chambers easily.The die's now set to minimally set the fired case shoulder back.
One other way to make tiny but accurate adjustments to die position is the following:
http://s860.photobucket.com/user/jepp2/media/DieAdjustment-1.jpg.html
Print them on full size label paper then use the .002" one to stick on your sizing die's lock ring. Follow the directions to mark then adjust your die for precise settings.
Or buy an RCBS Precision Mic or Hornady LNL Case Gauge to measure your case headspace (head to shoulder reference) and adjust the die so fired cases are sized to set their shoulder back .002".
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