7mm Weatherby and 160gr Accubonds - which powder?

[RJR-51]

Shooting 160 Accubonds, my Rem custom in 7mm Wby likes 70gr 4831sc for 3030fps out of a 25"
Schneider barrel. This load shoots to 1/2moa. RL22 got me about 100fps more velocity but not
quite the accuracy. Although not necessarily an elk load my most accurate recipe out of this rifle
is 73gr RL22 with Barnes 140TTSX @ 3400fps. Great deer load. Other powders I have tried without
much luck are RL25, 7872ssc, Retumbo, and IMR 4350. Your results may be different. Good Luck!

 

[Elkman]

Dr. Mike
My question was a serious one, I was not meaning to draw attention to the mistake, I make way to many of them to care. What are the symptoms of "senistivity" I have shot down to 0 F. and near 100 F, but I really don't know what to look for, I guess? What happens does the cartridge, misfire? or hangfire? I doubt I have experienced it but wanted to know.?

 

[DrMike]

Bill,

I did have a poor choice of words (senior moment). The only temperature sensitivity I've observed is that in very low temperature, velocities drop measurably. In very high temperatures, pressure can rise to excessive levels. The concept of temperature stability is that the powder is less affected by extremes of temperature. In a general sense, double base powders are more temperature stable (less temperature sensitive) than single base powders. However, the powders that are marketed as temperature stable show less tendency to generate excessive pressure in high temperature environments and resist losing velocity (maintaining pressure levels) in low temperature environments. The degree of sensitivity varies with powder, bullet weight, primer brisance, case volume, etc.

 

[Oldtrader3]

My best velocities and accuracy for Weatherby cartridges has been IMR 7828 SSC. Admittedly, I have not used Ramshot and some of the others but I can get Weatherby factory velocities and accuracy with IMR 7828 SSC in a 26 inch barrel and with nothing else that I have tried in my .340 Bee. That is the powder that Weatherby uses. Just my $.02.

Admittedly, living in Washington, our temperature ranges are less in western Washington than other states.

 

[DrMike]

Realistically, the velocity loss on most of the cartridges I have shot at -30 C or lower, while measurable, was not sufficient to serious degrade the trajectory of the bullet. I do load development year around, but I do check my hunting ammunition near the time I will be hunting. I do not do a great deal of long-range shooting, so velocity drops are generally insignificant in maintaining the target during a hunt. It the temperature is above +20 C, I likely will not pull the trigger as I do not want the meat to spoil.

 

[Elkman]

Thanks mike,

I know better than to leave ammo in the sun on hot days but was not sure about the cold. I have the nylon buttstock carriers on my rifles while hunting. The ammuntion is subjected to the cold temps and are essentially the same temperature as the outside. I also leave my rifles in my unheated truck at night to keep them from sweating, going in and out of the camper.

 

[Elkman]

OT

I am thinking that water damage is our biggest concern here. I have literally poured the water out of the barrel channel, and action area at the end of a days hunting on the wet side. That has been a couple of years ago, my Washington hunt this year is with a bow. I am hoping for the first season but will probably be working then. So next up is late October in the rainforest.

 

[DrMike]

Bill,

Your practises mirror my own. I don't leave ammunition in the hot sun (not even when shooting from the bench). I leave my rifle in the truck when bedding down for the night to avoid condensation building up. I carry my ammunition so it is near ambient temperature in cold weather. When shooting in extremely cold weather (say -20 to -40 C (the coldest I've actually hunted)), I may carry my ammunition in an inner coat pocket, though the cartridges will have been chambered when the stalk is actually begun. I have no doubt that the cartridges cool pretty quickly at those temperatures, as I'm certainly cooling quickly. :shock:

 

[Oldtrader3]

I carry ammo in an inside vest pocket, under my shell but not next to my body to assure constant humidity and temperature. However, this does not help shells that are in your rifle's magazine, gettin wet, all day. I usually shoot the chambered round before getting back in the truck at the end of the day if it has been snowing or raining or if the bullet lead tip is buggered. This is just to eliminate any bullet dielectric corrosion bonding from humidity or tip damage which might interfere with accuracy.

 

[Dr. Vette]

One more thought - I have Weatherby factory loads in 160 gr Nosler Partition, 139 grain whatever, 175gr PSP and Hornady loads of 154gr Interbond. I don't have any factory Wby 160 grain AccuBond loads.

Given the longer length of an AB vs an NP, much less the difference with a 139 or 175, any suggestions as to COAL with a 160 grain AccuBond?

Thanks,

Patrick

 

[DrMike]

Patrick,

On a Weatherby, you'll likely need to load to the magazine (3.360 inches).

 

[SJB358]

I would load them at Mag length to start with. With the freebore, you'll likely just tweak the powder charge to get the accuracy you are looking for. Good luck, that 7 Wby is a cool cartridge!

 

[Oldtrader3]

I still use the IMR 7828 SSC loads for my Bee and my 7mm mag as was suggested on the Weatherby Rifle forum listing of Weatherby factory loads. I have never beat speed or accuracy with any other powder in the Bee rifles and it equals factory loads with freebore. FWIW.

 

[Gm weatherby man]

I have enjoyed reading all these posts, some day i'll own a 7 mm bee.