Berger 220 LRHT 300 WM keyholing

[Paqueo]

I’ve been loading for a 300WM Rem 700 Sendero 26” original barrel 1 in 10” twist.

Interested on shooting it as far as possible.

At 1,380 yards found that Berger 220 LRHT bullets were keyholing.

Berger Twist Rate Stability Calculator indicates:

Your bullet is STABLE.

Your bullet is flying with full stability. You can expect good groups and your BC is optimized.

SG = 1.59 Bullet BC (G7):0.369 Your bullet is achieving its max BC. Your twist rate is optimized for this bullet.

My Kestrel indicates the remaining velocity at that distance and conditions is still above transonic – 1,445 fps

Load was 70.7 grain of N560 with a COL of 3.67” and a muzle velocity of 2830 fps

Wanted to extend the distance a bit more. Any sugestions? I’m limited to Vihtavuori powders and a few other European ones.

Tried with N565 but 72.5 grain is a compressed load with that COL and only gives around 2700 fps. Cases are Lapua with 243-245.5 grain.

Try a different bullet?

Thanks in advance

 

[Aftermath]

You may be limited by the twist.

I use 210 VLD leaving at 2950 fps and 1:9 twist. I have not noticed any keyholing to 1760 yards. I've made a very few good hits even farther but only on rocks so I don't know about how the bullet is impacting.

I'd try to get velocity up closer to 3000 fps and/or use a lighter bullet.

 

[Bacarrat]

This gives a good breakdown of what it says, isn't always true.

 

[Supersubes]

Ive shot about 500 220 LRHT’s out of a 10 twist. Your rifle is clearly not stabilizing them. Have you actually measured your barrel twist? This is going to come down to swapping bullets, or swapping barrels. Changing powder and charge weight isn't gonna do it.