Varget for 7mm Rem Mag Loads

[jwest]

Calgunners,

Do any of you use Varget for 7mm Rem Mag loads?

Of the recipe books I've looked at - Varget is only used for bullets up to 130 grains. Have any of you used Varget for 150, 160, 175 grains?

Thanks,
jwest

[ar15barrels]

Varget is too fast for heavy bullets in a magnum cartridge.

[Fjold]

Varget is too fast for heavy bullets in a magnum cartridge.

Fixed it.

OP if you look at the data Varget will always get you 100-200 fps less velocity than the slower burning powders. It just burns to fast for the big case.

[freakshow10mm]

Varget works very well in the .375 Holland, so your blanket statement about magnum cartridges isn't exactly the gospel.

[Fjold]

Varget works very well in the .375 Holland, so your blanket statement about magnum cartridges isn't exactly the gospel.

You are correct. I should have said low expansion ratio, magnum cartridges since the large bore magnums load much more like non magnum cartridges.

Varget is too fast for heavy bullets in the 7mm magnum cartridge.

Fixed it again.

[6mmintl]

Reloder 22

Have you tried it? I have 4-5 lbs if interested, will trade for varget

[ar15barrels]

The bore size does not matter.
Heavy relates to caliber so while 175gr 7mm bullets are heavy, 175gr 0.375 bullets are not.

I stand by my original statement.

[jwest]

Thanks Randall.

[jwest]

In case anyone is wondering - here's my 'first' recipe:

Win 780 - Yep, I got some from I&S.
Rem 9 1/2 Mag primers
Brass from Remington ammo purchased from Wally World.
~ 60 grains starting load.
Hornady 175 grain bullets.

Is it just me - or do most of you guys like Hornady bullets? Especially for plinking/target practice?

[freakshow10mm]

I like them. Cheaper than the competition and just as accurate. Hornady makes a fine bullet. I use them in .224 and .375, 10mm for hunting. I just wish they bring back the .400" 170gr XTP.

Winchester Supreme 780 is the factory powder for their 7mm Magnum ammunition. You should see fine results from it.

[Fjold]

Bore size versus cartridge case capacity makes the major difference on how fast of a powder you need.

A barrel ahead of a cylindrical case has a high expansion ratio while a smaller-diameter barrel ahead of a necked-down case has a lower expansion ratio, because the smaller-diameter bullet has to travel farther to expand the burn space behind it by as much as a case-diameter bullet expands it in a much shorter forward travel.

In two barrels of the same length, the bullet's trip to the muzzle can quickly double the burn space in a cylindrical case but the burn space behind a bullet from an extremely necked-down case may not double before the bullet reaches the muzzle of a very short barrel.

IOW, It's a measure of how many times the bullet's travel to the muzzle expands the burn space behind it in a given length of barrel, for a given cartridge. A .22 Long Rifle has a much higher expansion ratio than a .220 Swift — because the bore volume of a Long Rifle barrel is several times as much as the net volume of the case's powder cavity. The bullet from a .220 Swift would need an incredibly long barrel for its travel to expand the burn space an equal number of times the volume of the Swift cases's net powder cavity.

That's why all the straight walled pistol cartridges and shotgun shells require really fast powder, you need a powder that burns quicker to keep pushing on the bullet as the size of the combustion area multiplies so quickly.

You could put a 120 grain bullet in a 38 special case and it would still require a faster powder than if you took a 38 special cae and necked it down to 25 caliber and used a long 120 grain bullet in it. Because the the expansion ratio is so much lower for the necked down case the pressure during combustion would peak at a higher level because the combustion area is smaller for the the period that the bullet is just starting to move.

In the case of the 7 Mag versus the 375 H&H Magnum. The difference in the expansion ratios of these two cartridges is great enough to make two different quicknesses of powders optimum for these two cartridges. The lower expansion ratio of the 7 Mag calls for a slower powder — IMR 4831 or IMR-7828 for example. The higher expansion ratio of the .375 H&Hl calls for a quicker powder such as Varget or IMR 4064. If you add a heavier for caliber bullet it also compounds this, requiring an even slower powder to be used but the major factor in what powder to use is the case volume to bore ratio.

[jwest]

Thanks for the explanation Frank,
John

[freakshow10mm]

Yes, very good explanation.

[jwest]

I like them. Cheaper than the competition and just as accurate. Hornady makes a fine bullet. I use them in .224 and .375, 10mm for hunting. I just wish they bring back the .400" 170gr XTP.

Winchester Supreme 780 is the factory powder for their 7mm Magnum ammunition. You should see fine results from it.

Adam,

Thanks for this information - will give me a little more confidence when I shoot this weekend.

Regards,
John

[9-12]

For 7mmRM

H4831SC, H-1000, or Retumbo. Retumbo works well with the 162g A-Max.