Large rifle primers vs magnum primers ??

[Jolantru]

Need help from experience reloaders.

I use CCI large rifle in my 300 win mag.
Does the cold weather affect accuracy ?
Should I be using CCi magnum ?

For some reason I am 5” low today at 100
-10 here today

[SlightlyDistracting]

It will affect your point of impact and velocity. Could also be your powder choice as well. Some powder is very temperature sensitive
I use magnum primers or br2's
Being a 300 win mag I would not reload with large rifle primers. I would definitely be using magnum primers.
I develop loads with with magnum primers. Then there is no guessing. For my 22-250 I use magnum or bench rest primers.

[YYC338]

I can't imagine it would make that much difference. What powder are you using? There was an old rule of thumb out there that over 65gr + or - you should use magnum primers. I think all the published load data would use magnum primers in the 300WM

If you're using ball powder, it's supposed to be affected by cold weather. Not sure -10 makes that classification of cold.

Of course if your handloads were developed using standard primers you should reduce those loads and work up again using magnum primers, generally speaking.

[SlightlyDistracting]

5 inches @100? That does sound like a lot. Did something change on your scope? Do you have the magnification ring same position as when you sighted at 100?

[Jolantru]

I’m using imr 7828

I tried my scope magnification at the setting I sighted it in at and different spots. Didn’t seem to matter.

Scope mounts are tight and i don’t remember dropping or bumping it. I can’t think what else it could be.

[Pioneer2]

I use them in everything ..except cast....especially ball powders.Funny even in a little CZ 527 7.62x39 same loads with standard primers and mag ones.The mag groups were 1/2" and the standard 1" only variable changed were the primers and a miserly 25gr charge of H4198.

[Ebrand]

I use them in everything.

22-250 243 270wsm 3006 338fed 7stw 338 win mag 300 win mag.

I have no temperature issues.

I have no pressure signs and my loads are are developed to max or more.

[SlightlyDistracting]

Originally Posted by Jolantru

I’m using imr 7828

I tried my scope magnification at the setting I sighted it in at and different spots. Didn’t seem to matter.

Scope mounts are tight and i don’t remember dropping or bumping it. I can’t think what else it could be.

Imr 7828 is temperature sensitive.
I wouls start doing load development with magnum primers. Ditch the large rifle primers. For almost the same price you can get magnum primers. You will get much more consistency even in colder temperatures
Unless your scope is a first focal plane changing the magnification will absolutely change your point of impact

[elkhunter11]

Originally Posted by SlightlyDistracting

Imr 7828 is temperature sensitive.
I wouls start doing load development with magnum primers. Ditch the large rifle primers. For almost the same price you can get magnum primers. You will get much more consistency even in colder temperatures
Unless your scope is a first focal plane changing the magnification will absolutely change your point of impact

With a standard crosshairs or plex reticle, changing the magnification will not effect the point of impact unless the scope is defective.

[Buckhorn2]

Im not sure about your powder being temperature sensitive.as im just starting to reload but i can tell you that your point of impact should “NOT” change with magnification change. Unless you have a very old scope that is tracking when you adjust the zoom. or a broken scope. I have a new 100 dollar cabelas scope on my old hunting rifle and it does not change with zoom. Thats the whole point of being able to zoom your crosshair stays zero. If you have a bullet drop reticle that will change with zoom but the center point of aim will not. Try some factory ammo with same grain bullet. If your point impact comes up (obviously the point impact wont be the same as your handloads) then id look at your powder. If it shoots low then id look at your scope.


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[SlightlyDistracting]

Originally Posted by Buckhorn2

Im not sure about your powder being temperature sensitive.as im just starting to reload but i can tell you that your point of impact should “NOT” change with magnification change. Unless you have a very old scope that is tracking when you adjust the zoom. or a broken scope. I have a new 100 dollar cabelas scope on my old hunting rifle and it does not change with zoom. Thats the whole point of being able to zoom your crosshair stays zero. If you have a bullet drop reticle that will change with zoom but the center point of aim will not. Try some factory ammo with same grain bullet. If your point impact comes up (obviously the point impact wont be the same as your handloads) then id look at your powder. If it shoots low then id look at your scope.


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Let me clarify. Your point of impact will not change. But your point of aim will when changing maginfication

[Salavee]

Originally Posted by SlightlyDistracting

Let me clarify. Your point of impact will not change. But your point of aim will when changing maginfication

Does changing magnification change your point of aim .. or possibly the point of impact ?
Seems to me that if I hold on the X at 4 power, I can still hold on the X at 16 power but the POI might be off a bit depending on the optics.

[SlightlyDistracting]

Originally Posted by Salavee

Does changing magnification change your point of aim .. or possibly the point of impact ?
Seems to me that if I hold on the X at 4 power, I can still hold on the X at 16 power but the POI might be off a bit depending on the optics.

I stand corrected. I actually recently read an article about it. Been trying to find a link. It talks about how most scopes, unless they are high end your poa will change somewhat when changing magnification. Obviously it was an opinion. But he gave strong arguements why most will change. It was durastic and sometimes very minimal. But the authors opinion was that it will change in almost all except high end glass. I dont remember it mentioning different reticles. He basically had me convinced most scopes will change unless they are in the first focal plane. My bad....

[Salavee]

Originally Posted by SlightlyDistracting

I stand corrected. I actually recently read an article about it. Been trying to find a link. It talks about how most scopes, unless they are high end your poa will change somewhat when changing magnification. Obviously it was an opinion. But he gave strong arguements why most will change. It was durastic and sometimes very minimal. But the authors opinion was that it will change in almost all except high end glass. I dont remember it mentioning different reticles. He basically had me convinced most scopes will change unless they are in the first focal plane. My bad....

Not a bad, as it can get quite confusing. Sometimes even the point of aim will appear different . For all intents and purposes a SFP 'scope will induce some POI shift. It can be checked on any 'scope if you have a Collimator. The only way to avoid it completely seems to be FFP.
I always zero my SFP's at the max magnification .. where you really need the enhanced accuracy at longer ranges.