VV Double Base Powders 540/550/560

[260VLD]

Researching VV DB Powders , I quite often see the comment " temp sensitive " but have yet to read an extrapolation of that statement and therefore would be extremely grateful to anybody who could expand on the statement " temp sensitive."

And would anybody have a starting load for .260 Rem with 85 grain Sierra HP's with N540 ?

regards
Mike.

 

[Spuds]

Temperature sensitive refers to muzzle velocity change due to powder temperature change. All powders have a normal temperature coefficient where chamber pressure will increase or decrease dependent on powder temperature. The greater the temp coefficient, the greater the change in chamber pressure/change in degree of temperature. Powders with a high temperature coefficient are considered temperature sensitive. Some ballistic calculators have an entry to account for the change in MV/deg. temp.
Since I have not tested VV powders, I cannot comment on their temperature sensitivity. Below is a link to a write up by Shawn Carlock on the 338 Edge +P testing that would give me pause to automatically believe the VV N series powders are temperature sensitive. 338 Edge +P

VV'S website has reloading data, but 100 gr is the lightest bullet.
Products - Lapua

 

[260VLD]

Spuds many thanks , just read that link you posted re the 338+P , I guess I will no longer concern myself with temp sensitivity.

regards
Mike.

 

[foggybottombob]

Just as an observation. VVN560 gives the highest velocity attainable in a Win .270 with 130 grain bullets without showing high pressure signs. But I have found big variances between lots of the powder. I have to load 60.4 grains now to get the same velocity that 59.7 grains gave me in the last lot. That is more lot to lot variance than I have seen for any other powder I've used.

 

[260VLD]

Foggy , good to know but have you tried blending your lots ? I usually buy 8 kilos of Varget at a time , when the old lot is about half gone , I blend in a bucket a canister of the new with the old , never have a velocity issue , I don't know why it works but it do ! My 'smith , a noted F classer put me on to it.

regards
Mike.

 

[foggybottombob]

Last time I bought N560 was more than a year ago. I got 5#. I have not seen any for sale since. Powder is so hard to find nowadays that you need to have a lot of different loads worked up so you can load for whatever powder is available. Have not seen any Ramshot anything other than Tac for over a year.