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Author Topic: Ask RBros Thread  (Read 26600 times)

Offline Bob33

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Re: Ask RBros Thread
« Reply #15 on: August 23, 2016, 01:56:58 PM »
Thanks!
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Offline Branden

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Re: Ask RBros Thread
« Reply #16 on: August 23, 2016, 02:49:23 PM »
What do you think of Trigger Tech riggers?

Regards, Branden

Offline Bushcraft

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Re: Ask RBros Thread
« Reply #17 on: August 23, 2016, 03:09:21 PM »
Great idea for a thread!

Where is the best/correct place to measure sight height (center bore to center scope) when using a base with 20 MOA built into the base? And, how much does it really matter?

Here is an easy way to do it.  Lets use the following scenario:

You barrel shank is 1.25" diameter, so half that is: .625"
Your scope is a 30mm tube or 1.181", so half that is: .5905"
The distance from the top of your barrel at the recoil lug area to the bottom of the 30mm tube section is: .729"

Add those all together and you come up with 1.9445", round that to 1.95" and put that into you ballistic app.  A slight difference in height won't make that much difference, but if you leave it at the default number of 1.5" of most apps, you would be a bit off at distance using this example.

Hmmm...the how-to wasn't the question.  Got that.

How much, if any difference does it make when/where measuring the sight height when using a 20 or 40 MOA base?  For the sake of taking it to the extreme to see if there is a gnat's ass worth of difference, for example let's use a 200 MOA base and a long NF 5-25 NF-type scope.  Is the correct place to measure at the eyepiece, turrets that house the reticle or the objective.  Each will represent a significantly different measurement.  So, where is the best place to measure and what, if any, real world difference does it make?
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Offline rbros

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Re: Ask RBros Thread
« Reply #18 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. 
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Offline Bushcraft

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Re: Ask RBros Thread
« Reply #19 on: August 23, 2016, 03:27:40 PM »
Thank you.
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Offline Jolten

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Re: Ask RBros Thread
« Reply #20 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.
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Offline Angry Perch

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Re: Ask RBros Thread
« Reply #21 on: August 23, 2016, 04:23:03 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.

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?

Offline rbros

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Re: Ask RBros Thread
« Reply #22 on: August 23, 2016, 04:29:28 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.

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. 
R Bros Rifles
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Offline rbros

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Re: Ask RBros Thread
« Reply #23 on: August 23, 2016, 04:33:53 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.

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?

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.
R Bros Rifles
www.rbrosrifles.com

Offline brew

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Re: Ask RBros Thread
« Reply #24 on: August 23, 2016, 04:54:25 PM »
really cool thread...good reading--thanks for the info
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Offline Jolten

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Re: Ask RBros Thread
« Reply #25 on: August 23, 2016, 05:34:50 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.

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.

Hmm.... I'll have to try that. If it was that simple I might kick my own butt for that.
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Offline WoodlandShooter

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Re: Ask RBros Thread
« Reply #26 on: August 25, 2016, 01:31:11 PM »
building an AR10 (DPMS) looking for a 22" 7.3 or 7.5 twist barrel in 243. Want it to be relatively light, but also hold zero for strings up to 15 rounds per stage. Using a JP lightweight carrier, and a adjustable gas block.

what contour on the barrel, and will you build the barrel assembly?

Offline rbros

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Re: Ask RBros Thread
« Reply #27 on: August 26, 2016, 10:04:06 AM »
building an AR10 (DPMS) looking for a 22" 7.3 or 7.5 twist barrel in 243. Want it to be relatively light, but also hold zero for strings up to 15 rounds per stage. Using a JP lightweight carrier, and a adjustable gas block.

what contour on the barrel, and will you build the barrel assembly?

I think our buddy Glen Seekins is running his AR10 barrel at a .750-.800 at the muzzle in a 24" barrel.  I certainly wouldn't go any smaller than that.  Unfortunately, I don't do any AR10 barrels at this time.  I used to, but unless a guy had a premium upper, accuracy was hit or miss.  Had the most problems with DPMS uppers and their consistency.  Drop the same barrel into a premium billet upper and they shot lights out.
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Online andersonjk4

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Re: Ask RBros Thread
« Reply #28 on: August 26, 2016, 10:23:15 AM »
Do you do any re-barreling of metric threaded actions... Weatherby, Howa, etc?

Offline rbros

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Re: Ask RBros Thread
« Reply #29 on: August 26, 2016, 12:08:44 PM »
Sorry, Remington's and customs only
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