My first real surprise using Hornady data - 7mm-08

[119er]

7mm-08 Rem - Rem.700 SPS Varmint 26"
Case: Remington (RP)
Bullet: Hornady 139gr SST - seated -.015" from touching, +/- .125" below cannelure exposed above case mouth.
Primer: Federal GM210M
Powder: Win 760
Average actual velocity @48.8 gr. was 3012fps compared to advertised 2900fps.

I tend to believe that the data in Hornady's 8th Ed. book is on the more conservative side. At least my experience with a good number of their loads being put over my chronograph has led me to that conclusion. This is debateable but has been my observation. Regardless I still work up from safe levels despite my beliefs.

To my surprise today I was getting higher velocities than their data suggests. No typical signs of pressure were noted. Although pressure signs can be notoriously unreliable I felt safe to continue. The groups opened up above 48.0gr @2970 so there is no need to push that hard again. All this while the loads I worked up with RL-15 were below average as usual. (Same components/SD)

Moral of this story: Never assume anything no matter what your experience level.

I actually prefer to have these anomalies every so often to keep me from becoming complacent and to remind me of the nature of what I am working with.

 

[morcey2]

Hornady used a 24" barrel. That extra 2" of barrel you have can give you anywhere between 50 & 100 fps. I wouldn't be too worried about it.

Matt

 

[blarby]

Hornady used a 24" barrel. That extra 2" of barrel you have can give you anywhere between 50 & 100 fps.

That plus the extra gas room in the cartridge from your seating depth could do it.

That primer might not hurt, either.

My wife has a short 7-08, I wish we could get those velocities !

IF you like that, try the speer 110 gr TNT's- those thing ROCK for varmint !

 

[morcey2]

IF you like that, try the speer 110 gr TNT's- those thing ROCK for varmint !

I shoot those out of my 7x57, but I've only been able to shoot paper with them so far. Very accurate at about 3100 fps.

Matt

 

[gamestalker]

No kidding about those 110 gr. TNT's blarby, I absolutely love them from my 7 mags. @ about 3600 fps.. They literally blow coyotes up, and turn just about any varmint into a red spray. But so does the 100 gr. Sierra HP, and at slightly higher velocities of 3700-ish fps..

As for Hornady data, it might be on the conservative side for what ever viable reason, but I too often experience higher velocities that conflict with published velocities. But as RC pointed out, barrel length can most definitely be a factor.

GS

 

[steve4102]

Moral of this story: Never assume anything no matter what your experience level.

The Moral of this story is "Check your barrel length against your manuals, before you compare velocities.

 

[119er]

I should have been more clear when I said I have shot many other loads over the chrono from this rifle with Hornady data. The barrel length does effect velocity but it is a constant. Most times I won't reach their velocities at a given charge weight even with the extra 2" of barrel. That is why I was so surprised to see a load go above average. This is a condition unique to Win760 in my rifle so far.

I didn't really have a point to my post. Just an observation to share.

I do want to try some lighter bullets too. I don't get to do any varmint hunting around here. I usually take this rifle hog hunting though. It is very effective but a little heavy and long to carry around much. Maybe a shorter 7mm-08 is in order.