Guys,

I was advised to use VihtaVuori N160 to load for my 6.5X284 by a regular shooter in the Fort Benning matches. I obtained some powder and load data directly from the VV-Lapua website. I started a grain under maximum for the 140 SMK and had brass flow into the ejector hole with Norma cases, had to back down another grain. Consulting the Sierra manual, the VV maximum is 6 grains over the Sierra max! I found best accuracy with IMR 4831 and so stopped using the powder.

When I obtained a new 300 WM this past week, I decided to use the N160 I had. I once again consulted the VV-Lapua website and started a grain under max. with a 180 NAB. Looking at my Nosler manual, I discover the load I used is 2.5 grains over Nosler's max FOR THE 165 GRAIN! I now don't know if I should even try these through my gun.

Can someone more-experienced with VV tell me why such a differential in the data?

What cases, primers, bullets Lapua did use? Were they the same as yours? What was is throating length, chamber real size, neck diameter of your cases? Were you shooting bullet stuck in the groove? What were your barrel and their barrel? Was there a big temperature difference between Lapua's lab and place you shoot.
All these factors can make pressure skyrocket.When you develop new loads better get down 6 to 10% and look at pressure signs. Chrono is also a big help, if you're going faster than most already tested loads you're sure over pressure. Lot of shooters use VihtaVuori powders both sides of the pond and generally the variation front lot to lot seem very low so check all the variables with friends load and test it again.
In France i use VV powders for some high intensity cartriges like 338Lapua, 300Winch Mag 220MK, 300WSM 190MK without any problems. We shoot from 200 to 800m (220yards to 880yards.

Dom

My bullets were exactly the same as used for the data with the 6.5, and the same manufacturer and weight with the 300. Nosler lists the exact same data for all bullets they make; why should I not be able to use the same powder manufacturer's data? I never jam bullets and have no idea about the other variables, of course, but these are things that a supplier of data has to take into account. I understand what causes pressure, but the point is, if I reduce VihtaVuori's max load by about 8%, I am still at what Nosler recommends as maximum. This should not be. Either Nosler is overly conservative, or VihtaVuori is overly liberal. In the case of my experience with the 6.5, I would've wrecked my cases, if not the gun, at 2.5% under VihtaVuori's max load, and that's 0.025" off the lands! I know someone here can shed some light. By all means...

VV data on their web site uses Lapua bullets and brass for their 6.5x284 loads and not Sierra and Norma cases.
I don`t see Nosler useing VV160 with any of their 180gr bullets in the 300 Win Mag on their web site, or in their manual, although Lapuas web site does show the 180gr partition with it, again useing Lapua brass.
As to why the difference in available data...who knows for sure. I do know of a 270 Win though that with 140gr Hornady SPs maxs out at 55gr of R22 for ~3030 fps from a 26" tube. The Hornady manual says 59.7gr is max with this wgt for 3000fps. The rifle just don`t agree.

Starting at one grain below maximum is reckless, even with identical components because your chamber and barrel will undoubtedly not be dimensionally identical to the one in which the loads were developed. I have seen similar signs of high pressure with loads starting in the middle of the ranges in the manuals. Most of my rifles (both factory and custom) will top out well below one grain less than the maximums in the manuals.

Start low, watch the chronograph and stop when you get the velocity that you want. If you encounter the conventional signs of high pressure before you reach your desired muzzle velocity, you should try other powders. Even so, you may not be able to get the velocity that you want in a particular rifle, regardless of what powder you use. There is nothing magic about a particular muzzle velocity. The important thing is how well a given load performs for your particular use.

mudhen,

that's an interesting take. I normally prefer Nosler or Sierra data and will use data even for a different manufacturer's bullet so long as it's the same weight and profile. I have loaded for many guns, 221 Fireball through 375 H&H, including Ultra Mags and SAUMs, and have only seen pressure signs below manual or website maximum with two guns, one my 6.5X284 with VV/Sierra/Norma, and the other a Kreiger-barreled 300 SAUM using IMR4350/Remington (i.e.,JUNK) brass/Nosler Accubonds. In the case of the 300 SAUM, switching to Nosler brass solved the problem altogether, even using the same charge, at the gunsmith's recommendation.

Maybe VV tests at 20 below, and Lapua cases eat barbed wire and crap nails for breakfast. Oh well...I'll be more careful with VV's data in the future.

Mudhen's take is also exactly what every loading manual recommends. There should be no surprise there.

I also wonder if VV loads are to SAAMI specs. I'll have to check my loading manual later today to see which standard they use in load development.

This question is a good one to ask of Mule Deer on this site. Don't be surprised by the answers.

Bad trend here.

Mudhen nailed it.

My rule of thumb, if the components are exactly the same, start at least two or three grains less than max and work up. If some component is different, start 5 grains less. Now that's for charge weights of 50-70 grains. If you are loading a big boy, like a large case Weatherby or Lazzeroni, start 10 lower than max. Had I not done this with a Sako/Lazz Warbird, I could have eaten the bolt. It got velocity, and pressure, about 6-7 grains below max.

Reloading information used to suggest starting 5%-10% below and working up, which generally follows your rule of thumb.I don't see it in print that way anymore and I don't know why. I always felt it was the best way to work up to the Safest Maximum Load in a particular rifle, get long case life, and do no harm to yourself or your weapon.

The VV load are CIP which are as safe and secure as SAAMI and has Lapua and VV sell a lot in the US their loading datas are generally layer proof. More often problem with pressure, cases blown, gun destroy come from handloading. Hogdon traced that to be more or less 9999/10000 time the 1/10000 could be rifle problem or industrial ammo problem. Lapua tests are made in Lapua or VV ballistic loba and think temperature is controled accordingly to SAAMI/CIP rules
In my VV 4th reloding manual all the bullet and cases are Lapuas. With 139 Scenar load is from 43,2 to 47,2grs VN160. It looks like that the 140 MK from Sierra develop much pressure than Lapua's bullets. The same with .30 and .243 match bullets.
About 300WM, Lapua manual give the VN160 with 180 bullets but for target most of us use VN165 which give better accuracy with the 185Scenar (non moly)or the 220MK in my Stey or two Rem 700 with Walther barrels. With the 220 and will try the new VN570 for an higher velocity and better wind bucking. Again be very careful with different makes of cases. Try to weight some you'll surely be surprised.
If you want good infos complete and detailled on long range go to www.6BR.com you'll get lot of them!

If I am working with a new rifle, powder, bullet, etc., I generally look at multiple manuals for a given load and then try to decipher why there are differences in recommended charges (i.e. brass, primers, lower velocity, etc.). Then, I trend toward the conservative side and reduce by 10% or so and work up. Lately and if there is any chance that the load will be used in the summer, I have tried to max out a couple of grains below max or whatever shoots best. I started this recently after chronographing max loads worked up at 70 degrees that were getting an additional 200 FPS or so and some pressure signs on a 107 degree day.

But back to the point, if the Nosler data is more conservative I would start with that and back off 10% and work up. If no pressure at the Nosler max and the VV is higher, you may ease up a little watching the chrono as you go.

Aren't there substantial differences between the 6.5x284 Win and the 6.5x284Norma?

If using different components, all bets are off. Case capacities can and do vary from manufacturer to manufacturer. JMO, Dutch.

You're right DesertMuleDeer, do the same, i think the problem of Watson come from he ain't played the game right;

Dom

Update: the N160 loads averaged 3100 fps from a 24" barrel at 65 degrees F, with light ejector marks on the brass, though not flattened primers. After firing the third round, I had to bump the bolt handle up with my fist and stopped.

You guys are busy slamming my reloading procedures, but the fact remains that I have only experienced pressure signs below manual or website max EVEN NOT USING THE SAME BULLET AS USED FOR DATA DEVELOPMENT with now three rifles, two of which were using Vihta Vuori N160 powder and data with the same weight bullet from their website. The other was using Remington brass that proved to show pressure signs with factory loads. I normally start a grain or two below max with the data source I'm using.

This applies to 221 Rem. Fireball, 308 Win., 30-06 Spgfld., 300 WM, 300 RSAUM, 6.5x284, 300 RUM, 375 H&H, 358 Win., and 35 Whelen. I have used Rem. and Win. factory-chambered barrels, and custom-chambered Kreiger and Douglas. I have used Nosler, Sierra, Speer, Remington, Combined Technologies, and Hornady bullets, and Remington, Winchester, Black Hills, Norma, Lapua, Federal, and Hornady brass with Vihta Vuori, Winchester, Accurate Arms, IMR, and Hodgdon powders.

LESSON: when Vihta Vuori says maximum, they mean it.

Whether or not you got satisfactory results with starting one grain below max in other instances has nothing to do with whether the practice is safe or not.

That's like saying you always drive 90 mph on a certain road and have never wrecked. It doesn't mean it's safe, and it doesn't mean 90 mph is safe under all conditions.

Rifles vary, and powder varies from lot to lot. If I loaded like you do, I would have blown a lot of primers by now, because the correct powder charge will easily vary 3-5% with different lots.

Voice of reason....JB, I appreciate your safety assertions more than you know.

You have sent me to the green bullet puller on more than one occassion, before reaching the range, and facing who knows what.

I thank you as do my children and wife.

There is alot to sway a body to read loading manuals as conservative, but it's never a good idea, especially with an unfamiliar powder, bullets or rifle. Best to work up and familiarize.

Thanks! But part of the reason I state such things so fiormly I was young and dumb once, and blew some primers. That hasn't happened in a long time, and I continually strive to make sure it stays that way....