Does seating depth and crimping affect velocity?

[elmer deer]

I have a few questions for you guys to answer,
1) Does seating the bullet .005 off the lands change velocity as opposed to seating .020 off the lands?
2)Does a light crimp make velocity slower as oppossed to no crimp?
3)I shot some reloads with my 7mm rem the other day, it was -15c or a 5f (cold) my loads were
RL22 66.5gr with 140 accubonds out of a 26" barrel,Sauer 202, my average speed with these loads was 2975fps.The Nosler book list that laod at 3240fps with a 24' tube, WHY THE BIG DIFFERENCE does the cold affect the velocity that much or is my barrel a bit slow? It is a new gun this was the 2nd time at the range with it.
Sorry for all the questions guys
Thanks
Elmer

 

[Guy Miner]

1) Barrels are different. Possibly Nosler's barrel had a tight chamber?

2) Temperature can make a considerable difference in velocity. That much? Maybe.

3) Crimp and seating depth can play a role in pressure and velocity. I don't crimp any rifle, except my .45-70 Marlin.

Although I really like the 7mm Rem mag, I've noticed that some rifles produce some very impressive velocity, while others don't even come close to the figures published. Am sure there is much more to this, but I'd look at temperature as the biggest single contributor to your barrel being "slow."

Regards, Guy

 

[Desert Fox]

There's an explanation why there is such a disparity between your load and that of the Nosler.

First, the temperature is one factor.
Second, the Nosler test barrel probably has minimum chamber spec.
Third, Reloader 22 has temperature sensitive issue.
Fourth, Different reloading component.
Fifth, Barrel twist ratio
Sixth, Location (Elevation)

Seating bullet .005 to the land as opposed to .020 does affect chamber pressure. Seatin bullet closer to the land will increase chamber pressure.

Crimping doesn't make your load slower. Actually it's the contrary. Crimping can cause pressure to rise, thereby increasing velocity. I don't crimp my load.