I was loading 6-284. Data from Sierra manual claims 52.7 grs of N-165 should give 3500 fps. My cronograph measured only 3200 fps. Stepped up slowly with 0.5 grs increments up to 55,5 grs( N-165)= 3360 fps no pressure signs.
I am using Lapua 6,5 284 resized and neckturned brass,70 grs Ballistic tip, rem 9 1/2 primers. I think it�s not bad cronograph (crony beta) used it for 222, 270 and it�s close to the loadmanuals. Can you point out other load manuals or info loading the 6mm-284.
Barrel is 26 inch 1-13 twist.

A customer that came into my store had this very same problem.
The velocities which Vihtavouri lists seem to be very inflated. I believe my customer had the problem in a 45 ACP.
Just something interesting there.

-Spencer

Do yourself a BIG favor...don't believe ANY of the velocity dtat in ANY of the manuals!

I disagree, the majority of the manuals out there give honest tables, but a small minority of them like to pad their information.

No load info for VihtaVouri powder but have this from Metallic Cartridge Reloading 3rd Edition:

26" barrel using 70 grain bullet

*ALL MAX LOADS*

56.0\H450--3679fps yields 50,700cup
51.0\H414--3667fps yields 51,800cup
56.0\H4831--3762fps yields 51,800cup
46.0\H380--3402fps yields 50,200cup

From Hornady 4th Edition:

40.2\IMR3031--3500fps
40.8\IMR4064--3400fps
43.0\H4895--3500fps
45.0\IMR4320--3600fps
49.5\IMR4350--3600fps
52.5\H4831--3600fps

Don't expect any velocity tables to represent the velocities that your gun will produce with a given load.The companies printing the manuals are using a different gun with a different barrel,different chamber,different lots of powder,primers,bullets and brass and usually a different COL.All of these variations make it very unlikely that their velocity numbers will match your own.It is quite normal for differences to exceed 100fps and in many cases much more.

Yup, there are a lot of variables, their loads generally are higher than what the average guys get though, and that's peculiar. You'd expect that their velocities would be mid range. Fancy pressure barrel or not.

It seems to me , that their barrels and chambers must run a little on the tight side. Sometimes really tight.
Gunwriters have made the argument that " if you achieve the stated velocity with a given set of components, in the same length barrel, you have achieved the same pressure ."
Some of them imply that adding powder until the velocity is the same , means that the pressure is the same.
I do not agree that this is a particularly good idea, as it does not take into effect the variables of barrel problems ( tooling marks, pitting, microscopic cracking in the throat area , etc. )most of which you cannot see while looking down the bore.

Travis F.

Well, go to http://stevespages.com/table1.html

Take the time to look at the tables comparing what the different factory manuals state about loads and velocities and what I actually obtained at the range...

Seems like Sierra don't cheat fair. Many of the rounds they give data for were worked up in 26" barrels. For years, they used a Mauser 95 with a 29" barrel for the 7x57. They finally went to a 26" barrel in their latest manual.
How many of us hunt or shoot with rifles that have 26" to 29" barrels?
Sounds more like lying to me. Probably because of scumbag liability lawyers.
Paul B.

I have found the same problem with most published data and plenty loads on these pages right here. I am not saying they are lying. I'm just looking at my chronograph and my rifles results. That just tells me to believe it when I see it.