Almost new rifle - groups spread horizontal

Jayjay1

Jayjay1

Gunny Sergeant
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Minuteman
Oct 30, 2018
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#1
Hello guys,
got me a new Bergara B14 Wilderness Sierra for hunting in .270 Winchester.

I´ve tried some bullets but the groups weren´t good in the beginning.
I stuck with the Nosler 150gr. BT, which seemed to have the best precision potential.

Made a ladder test and found a plateau close to the maximum powder load (what Quickload said).
Primers and brass still looking good, I began to vary the OAL.

From 6 loads with different OALs (each 5 rounds), I had two loads spreading evenly horizontal and vertical at about 1.2"ish.
4 loads had only a vertical spread of around 0.4", but still a horizontal spread of round about 1.2".

I don´t now where, but in a book or in the internet I´ve read, that a horizontal spread can be caused by a too stout load.

Can somebody confirm this, or is this nonsense?
:unsure:
 
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#2
Jayjay1 said:
Hello guys,
got me a new Bergara B14 Wilderness Sierra for hunting in .270 Winchester.

I´ve tried some bullets but the groups weren´t good in the beginning.
I stuck with the Nosler 150gr. BT, which seemed to have the best precision potential.

Made a ladder test and found a plateau close to the maximum powder load (what Quickload said).
Primers and brass still looking good, I began to vary the OAL.

From 6 loads with different OALs (each 5 rounds), I had two loads spreading evenly horizontal and vertical at about 1.2"ish.
4 loads had only a vertical spread of around 0.4", but still a horizontal spread of round about 1.2".

I don´t now where, but in a book or in the internet I´ve read, that a horizontal spread can be caused by a too stout load.

Can somebody confirm this, or is this nonsense?
:unsure:
Click to expand...
No, a "too stout load" in of itself will not cause that horizontal dispersion. It really could be any number of things.

Of course, it'd really help to see pics of the series of shots. :rolleyes:

If this were me, I'd retest those 4 loads to see if I got the same results, then go from there.
 
Last edited:
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#3
Could be something as simple as your rear bag set up at the range. That can cause horizontal dispersion. What is your shooting set up at the range?

Take a look at this thread, start a post #1:

www.snipershide.com

The "Taylor was Here" Rear Bag - Answer - Compromise - Grande' *Shipping

I have a very unique take on your relationship with your rear bag and its relationship to your shooting. What for some is a total afterthought, given very little consideration beyond what is trending in the marketplace or is being promoted heavily by this shooter or that. My take comes from...
www.snipershide.com www.snipershide.com
 
#6
straightshooter1 said:
Of course, it'd really help to see pics of the series of shots. :rolleyes:
Click to expand...


Here ya gooooo .....

Load 5.3 looked very similiar to 5.5, 5.7 and 5.8.

Distance was a bit over 100yds.

That one flyer at 5.4 was the first shot at this test, cold bore.


IMG_2136.JPG
 
#8
Because it is a hunting rifle, I´ve shot front and back on sand bags.

Thought about mounting a pica rail underneath the forearm, to be able to mount a bipod.
:unsure:
 
#9
Jayjay1 said:
Here ya gooooo .....

Load 5.3 looked very similiar to 5.5, 5.7 and 5.8.

Distance was a bit over 100yds.

That one flyer at 5.4 was the first shot at this test, cold bore.


View attachment 8448326
Click to expand...
Basically, I just don't see anything that I'd attribute to any of the particular loads. Are these .1 gr increments?

When I see this kind of thing on my targets, invariably, I find it's that I'm not doing well with consistent trigger pull and/or cheek weld pressure. Even at 100 yds, wind can cause that kind of thing too.
 
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#16
Nothing I see indicates there has to be any issue with equipment or shooter ?
Any of the loads pictured would be fine for almost any typical hunting.
If you just want to chase better accuracy I would confirm the twist rate of your barrel and try some target bullets optimized for it.
 
#17
Jayjay1 said:
I did, tried to wiggle it.

The pica rail is torqued down and glued.
Mount and scope seem solid.
Click to expand...
That’s not much of a check. Take things apart and verify the assembly and torque of the fasteners. A “wiggle” that’s too small to feel, in the scope mount or the receiver screws for example, will give you the results you are seeing.
 
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#20
It doesn't take much. I just ran a trig calculator for 1/2 inch at 100 yards. That's a movement of only 0.008 degrees at the gun, which is less than 4 thousandths of an inch at the end of a 24" barrel. That's not the kind of looseness you'll "feel"
 
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#24
Well, a lot of good stuff inhere, I really appreciate that, thank you guys.

My Sierra Wilderness has only two small pillars, no chassis like the HMR has.
There is painting over that pillars, which is "rubbed" away where the system has contact to them, according you can see a little paint on the system in front and behind the screw holes.
Another option would be to make a bedding job, which I do on all of my rifles, after I´m sure I´m keeping it.
But not to lose the "1MOA guarantee" from Bergara I´m afraid to do so.

Should I remove the paint in the whole area, where the system sits in the stock?

For the might-be "wiggle" in the optical system.
A stopgap sits on the rifle right now, the final scope and mount are on my main hunting rifle until this rifle "shoots".

I´ve mounted a pica rail (-20MOA) on the system, torqued it down as the manufacturer recommended, secured it with loctite blue.
Mount is the Burris P.E.P.R. QD from my AR, with the Meopta Optika6 3-18x50.

The scope sits in the mount with 1 layer of tape, screwed down with the recommended torque from the manufacturer.
After your input I´ve ordered a higher quality mount from ERATAC now, wanted to replace the PEPR since a while anyways.

The rifle itself jumps straight up a bit (maybe 1") when I shoot, can´t tell that it moves sideways.

And I will test the two best loads again, and will reproduce both with a little less powder (-0,3gr.) as well, to see a possible difference.
Thanks again guys.

I will be gone and offline for one week, and then will have some work to do (as written above).

Thanks again,
cheers!
 
#28
Well, the PEPR is not a high-end mount, and I´ve made some good experiences with equalizing some mount irregularities with a thin tape.

Gunsmiths take quite some money to fit (grind and polish) mounts to scopes, so ...
:unsure:
 
#29
Jayjay1 said:
Well, the PEPR is not a high-end mount, and I´ve made some good experiences with equalizing some mount irregularities with a thin tape.

Gunsmiths take quite some money to fit (grind and polish) mounts to scopes, so ...
:unsure:
Click to expand...
I won't knock it as I can't say it doesn't help for lower end rings and mounts, but I would want to make sure it isn't contributing to the groups you're enquiring about by testing without the tape too.
 
#33
Jayjay1 said:
Well, finally.
:love:

Five shoots at 100 meters.

I did some with the rifle, tested some more loads, replaced the PEPR mount, worked on my fundamentals.
If that´s it, it is all I´m asking for, am very pleased with the result.

Should I bed it, or leave it as it is?


View attachment 8457256
Click to expand...
If it ain't broke don't fix it
 
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#39
hlee said:
1.2” at 100 yards is ~0.3mil. For a “6mph rifle,” that’s an 18 mph wind. Definitely breezy, but not crazy.
Click to expand...
Assume a 308 with FGMM. A headwind at 1 o'clock running from dead calm to 10 mph will give you just over 0.3 mils.

A 10 mph headwind switching from 11 o'clock to 1 o'clock will give you almost 0.2 mils. In my experience fishtailing headwinds are very hard to estimate. Give me a 20 mph crosswind any day - it is 0.4 mils but it stays at 0.4 and the mirage will tell you when to back off the gun.
 
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