7 WSM vs. 300WSM at 1000yds

[Hunter66654]

Trader, the BC's for JLK bullets are as follows: 7mm-168gr= .690, 7mm-180gr=.738, 308-175gr =.545, 308-190gr =.602, 308-210gr =.665 This info came from Jimmy Knox of JLK bullets.

[Mysticplayer]

From the guns that I have built and shot at 1KM, I would definitely go with the 7mm for these reasons.

If competing, weight and recoil will be issues so barrels can't be super long. Fatigue with the heavier bullet will affect groups. The WSM case is getting a bit small for real heavy 30cals. Perfect for the heavy 7mm.

Accuracy may not be at the vel level you need to make the 30cal 'work'. With the 7mm, even if it ends up being slower, the high BC will help at 1KM. Most barrels shoot their best at less then max pressures.

Compare the effects on a ballistic program. I bet you will find that BC plays a much larger role then vel when it comes to wind drift. drop is of little importance as you will know how far you are going. Misjudging the wind by a few MPH is pretty common and the higher BC bullet will shoot through those conditions better.

Jerry

[John Burns]

BC is the controling factor in wind drift. If two bullets have the same BC they will drift exactly the same no matter what weight each bullet is.

[Aussie]

John has it right . BC is the important factor , not weight . Time of flight is also important . IF BC is the same then velocity will govern which bullet drifts (and drops) most .

[Magmaniac]

Boyd Heaten shot this same bullet for matches he pushed them around 2,800 and for hunting around 2,950, not sure about barrel length but I beleive it was about the same length as what you stated.

[BountyHunter]

JD

I shoot the 300 WSM in HG and I can take a 210 JLK to around 2875 with good accuracy in a 30" Spencer barrel.

I am building a new 300 WSM with 30" Broughton barrel with the "5C rifling". It is the radiased lands like the Obermyer and Rock barrels. Broughton barrels are really kicking but lately and people are getting higher MV due to the rifling. This gun will be throated to shoot the 187 BIB flatbase bullets. Jim Hardy in NC is getting 3125 MV with 30 Broughton barrel in 300 WSM and Norma brass now and great accuracy.

This setup requires special long throat reamer as the bullet has pressure ring that must be in the neck.

Based strictly on the BC, the edge is to the 7MM WSM as I said before and I would look at the Broughton barrel with 1-9 twist if you want max MV and accuracy.

BH

[DMCI]

This is what I am getting out of a 28" 1 in 9 Lilja 3 groove 7mm WSM:

Win LRM Primer
Berger 180 VLD
Win Cases
VV N165 Powder

Grs. Velocity(SD)

61.0 2737

61.5 2757(6)

62.0 2780 Group size: .313"@100 yards 5 shots.

62.5 2800

63.5 2858(10)

64.0 2890(15)

75.3*F
29.75 in Hg
49.7 RH

Looks like more investigation for accuracy only needs to be made for loads from 61.5 to 63.0 Initial indications are that rounds have very excellent consistency.

On a second occasion, we visited the range with 180 Berger VLD and VV N165 but with F215M, a magnum match primer:

62.0 2834(9)
62.5 2866(8)
63.0 2895(7)
63.5 2916(6) Group size: .401 @ 100 yards 5 shots.

85.0*F
30.2 in Hg
25% Humidity

Interesting in this case the best group was the heaviest load. Some minor primer extrusion around firing pin, nice bark, light to medium recoil even with Break and 15# gun.

With WLRM primer, best group was 62.0 to 62.5. This is an excellent mid-range target load.

I think for now the F215M load will be the one loaded for target shooting.