Hunting Washington Forum

Equipment & Gear => Guns and Ammo => Topic started by: Mccabe on August 29, 2021, 02:07:19 PM

Title: Sighting in rifle
Post by: Mccabe on August 29, 2021, 02:07:19 PM
Hello, Iíve never had a issue before Iíve developed a load for my .300 ultra Iím using retumbo powder 84 grains Iím using Barnes 190 LRX I sighted my rifle in at 100 yards 1/2 inch group I went to 200 yards which should shoot a inch low I have a 1/4 inch group but Iím six inches low I should have to make any adjustments . Any ideas thanks tucker 


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Title: Re: Sighting in rifle
Post by: Mccabe on August 29, 2021, 02:20:19 PM
Here is the groups


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Title: Re: Sighting in rifle
Post by: Jolten on August 29, 2021, 02:25:11 PM
How are you calculating you should be an inch lower? Ballistic calculator? Did you verify your speed?
Title: Re: Sighting in rifle
Post by: Mccabe on August 29, 2021, 02:28:35 PM
I donít have a chronograph. Im just going off the box as if I use factory loads it says at 100 yards you should be 1inch high and 200 yards you should be dead on


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Title: Re: Sighting in rifle
Post by: Jolten on August 29, 2021, 02:42:25 PM
Box speeds don't work for reloads. What's your reloading manual say 84gr should get you?
Title: Re: Sighting in rifle
Post by: Mccabe on August 29, 2021, 02:52:02 PM
It says at 86 grains the velocity would be at 2950 . Which Iím using 84 grains. The factory loads is 3125 velocity .


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Title: Re: Sighting in rifle
Post by: Taco280AI on August 29, 2021, 03:08:58 PM
It doesn't matter what the factory ammo says, you're not using factory ammo. Guessing you're at 2900fps with your 84 grains, that should get you about 3 inches low at 200 with a 100 zero (without knowing all the variables).

Get a chrono. Or shoot at 200, 300, 400, 500... and find your actual trajectory then calculate your velocity off that.

Or it could be something you're doing differently with your shooting form at 200 vs 100. Parallax? Lots of unknowns  :dunno:
Title: Re: Sighting in rifle
Post by: Mccabe on August 29, 2021, 03:20:38 PM
Thanks I think Iím going to make 200 yards my zero and sight it in for that . And go from there Iíll be hunting goats in the olympics which more than likely will be a longer shot


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Title: Re: Sighting in rifle
Post by: Shadrach71 on August 29, 2021, 03:50:40 PM
Yeah way to many variables in this equation. As stated above you need to verify speed over a chrono to even begin to know part of the equation, then take it out to verified distances (200, 300, 400, 500 yards ect) so you can verify drops. Then enjoy your hunt and learn windage if shooting longer distances. Good luck on the goat hunt 🍻
Title: Re: Sighting in rifle
Post by: Magnum_Willys on September 21, 2021, 07:36:07 PM
You are right something strange is happening - you change something other than distance from 100 to 200 ?   
Title: Re: Sighting in rifle
Post by: JimmyHoffa on September 21, 2021, 08:28:57 PM
Scope height?
Title: Re: Sighting in rifle
Post by: Jolten on September 21, 2021, 08:46:59 PM
25.0   2907.2   1.10   4.14   0.0
50.0   2864.5   0.47   0.87   0.0
75.0   2822.2   0.08   0.12   0.0
100.0   2780.2   0.00   0.00   0.0
125.0   2738.8   0.20   0.14   0.0
150.0   2697.5   0.67   0.43   0.0
175.0   2656.8   1.46   0.79   0.0
200.0   2616.5   2.52   1.21   0.0
225.0   2576.8   3.94   1.67   0.0

My calculator says he should be just over 2.5" low at 200 at box speeds. I'm wondering maybe scope is loose, or canted.
Title: Re: Sighting in rifle
Post by: Jolten on September 21, 2021, 08:49:23 PM
Only way I can get muzzle velocity to match his 6inch drop is to drop it to 2200. Which seems way too low for 86gr
Title: Re: Sighting in rifle
Post by: Mccabe on September 21, 2021, 08:57:26 PM
I never changed anything from going from 100 yards to 200 yards . My scope height is 1 5/8 itís nice and tight.


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Title: Re: Sighting in rifle
Post by: mazama on September 22, 2021, 09:02:13 AM
Moving the position of your rest,or head or moving target at different to different angle,i used a pillow one time because I forgot my rest that changed my impact 3 inches.
Title: Re: Sighting in rifle
Post by: blackpowderhunter on September 22, 2021, 09:09:40 AM
i'd borrow a chronograph.
not saying your vel. is 2200 fps as calcs would suggest, but its hard to guess around velocity.
some barrels like something more than another, could be a funny batch of powder, whole bunch of stuff.
the weird part is that whatever velocity you're getting, they're grouping nicely  :chuckle: :dunno: :dunno:
Title: Re: Sighting in rifle
Post by: buckfvr on September 22, 2021, 10:01:29 AM
If you arent able to collect actual velocity data, you probably arent going to be able to resolve your issue.  In that case you may be well advised to buy a couple boxes of factory ammo for sight in and hunt until you have a chance to resolve the issues.  If the factory ammo does the same thing then you have other problems to resolve.   :twocents:
Title: Re: Sighting in rifle
Post by: Mccabe on September 22, 2021, 10:17:57 AM
Thanks I never had a issue before with factory ammo, just havenít found any for over a year and half I have a custom cds dial for that specific ammo not sure if it would throw it off using different ammo with that cds dial .


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Title: Re: Sighting in rifle
Post by: buckfvr on September 22, 2021, 10:35:42 AM
If the velocity data you used for the dials doesnt match collected data from your handloads, you will be off your mark.  If your dials were cut from "box" data from your factory ammo, you may have the same problem, however if its close enough it wont show that much until 500 yards or more.

Ill add, yes, I have had CDS dials and have tested 2 rifles that both had them out to 650 yards.
Title: Re: Sighting in rifle
Post by: Damnimissed on September 22, 2021, 08:55:43 PM
FWIW, that is an extremely mild load for RUM. I donít know anyone running under 90gr of Retumbo. Iím pushing 200gr AccuBonds at 3135fps with 92gr of Retumbo with no real pressure.
Title: Re: Sighting in rifle
Post by: Mccabe on September 22, 2021, 09:10:14 PM
I was just going off the Barnes load data it showed 86 grains as max, I called and talked to customer service he did say I can up it a bit just watch pressures . I did try 86 grains It just isnít grouping like I am at 84 grains.


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Title: Re: Sighting in rifle
Post by: Bushcraft on September 22, 2021, 09:26:55 PM
No offense intended, but how much experience do you have with handloading?  Everyone starts somewhere. It's good that you are asking questions.  I recommend stopping what you're doing and asking a lot more questions.  ;)
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