170gr Lee FN GC

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07Kingpin
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170gr Lee FN GC

Post by 07Kingpin »

Just picked up a Lee 170gr FN GC for the 300 BO 1:7 bolt action.

Looking for accuracy, hoping for 2 MOA out to 200.

With conventional and/or TL seems as though 1600-1700 fps could be realistic.

Have CFEBLK, IMR4227, LILGUN and H110- CFEBLK with 150gr Speers has met accuracy goals.

Thoughts/suggestions?
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dellet
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Re: 170gr Lee FN GC

Post by dellet »

Depends on bullet shape and alloy hardness.

In general, 150,000 rpm can be tough on lead bullets. 1700 fps. gets you around 175,000 rpm. in a 1/7 twist.

This might actually be a good place for CFEBLK, 4227 would be my first choice, of what you listed.

It doesn’t work exactly like this but group size at multiple distances will help sort out if they are spinning too fast. One inch at 50, 2@100, 4@200. Is what you might expect with a good bullet.
If the bullet is becoming unstable due to spin, deforming, it will be more like 1@50, 2@75, 3@100, 6@150 and some real outliers n the pattern. Oblong holes or key holes.

I had better luck starting at low velocity, around 1300-1400 and working up until I could see bullets becoming unstable.
300 Blackout, not just for sub-sonics.
07Kingpin
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Re: 170gr Lee FN GC

Post by 07Kingpin »

Thanks dellet,

With work being so crazy I haven't end loaded up the first batch- hope to this week and get out over the weekend.
07Kingpin
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Re: 170gr Lee FN GC

Post by 07Kingpin »

Finally got a quick trip to the range.

Set up at 50 and shot one round with a known load to check zero then four with the 170 cast:
Image

Not a match winner but off to a good start so moved to 100, dialed in a gues on elevation and fired four more:
Image

Initial accuracy is encouraging. Bullets are obviously staying intact and stable. This is probably helped by low velocity, average over 8 rounds:Image

But load seems fairly stable- ES was 10, not stellar but again, encouraging:Image

Only tried one load, 14grs of CFEBLK, figured best to start conservatively as Dellet advised.

Was pretty pressed for time and prob wasn't my best showing steering the rifle but not a bad start.

The one issue I did have was that the rounds would not feed from the internal box mag. Didn't have time to investigate yet but hoping some COL tweaks might help. Got home and borescope showed no leading at all.
07Kingpin
Silent Operator
Posts: 65
Joined: Sat Aug 10, 2019 11:03 am

Re: 170gr Lee FN GC

Post by 07Kingpin »

Tried 2 more loads, 15 and 16grs of CFEBLK. Accuracy trailed at higher velocities but was still in the 1.5 MOA range at 100.

Biggest issue is that these bullest flat will not feed from the Savage mag.

Going to try the .312 160gr and see how it does.
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