Guys I've been measuring Cartridge Overall lengths for my recently acquired Howa 1500 7mm WSM. The seller, dropmdead, had advised me that the maximum length of round which fits into the magazine is significantly shorter than rounds seated for the lands.
Anyway, with supplies of 140gn Gameking Spitzers, 140gn Nosler Ballistic Tips, 162gn AMax and 175gn Matchkings and Stoney Point OAL Guage I've been measuring seating depth with each round to touching lands and also using a Sinclair Hex Style Bullet Comparator.
The SAAMI spec for 7mm WSM has an overall length of 2.860"
Each of the above bullets creates the following COL with in brackets the measured length to the point at which the bullet touches the lands:
140gn Gameking Spitzers: 2.971" at which length the bullet does not seat by 1 whole calibre (2.288")
140gn Nosler Ballistic Tips: 3.114" (2.441")
162gn AMax: 3.153" (2.405")
175gn Matchkings: 3.132" (2.425")
Initial thoughts are these:
1. My habit for the past 20 years has been to measure chambering to Max COL and then work back by 10thou. This has been a good starting point and I don't know of a reason why this wouldn't be an equally good starting point in this calibre.
2. I'm not worried by rounds being too long to fit the magazine: I can manage with single feed.
3. This rifle is going to do some duty as a deer rifle and some duty as an informal plinker and having a similar BC, weight and length of bullet for both roles will keep it simple. (I've tried using AMax on beasts and won't do it again. Okay they create a blood trail but I'd rather see more ballistic shock.)
4. I'm going shopping for a different bullet for deer duty, longer and heavier than 140 gn
Those of you using 7mm WSM: what bullets have you settled to using please?
Do you load to 10thou off the lands or some other distance?