1-8 twist and 180 grn / sub.

[justshoot]

hey can I expect to balance-out 180 grners with a 1-8 twist, 17 inch. and do it below 1100 fps ? " With nice tight groups " like I do with heavier bullets ?
I do 200 grn.and above weight bullets good with the 1-8 twist doing subsonic vel. but I was wondering because I got a few hundered 180 grn. sitting here that I have no use for in loading my other .30 cal. centerfire rifles.
So before I waist powder, cases and chrony-time, I thought I would ask 1st. ..thanks.
.

[320pf]

justshoot,

If your rig can shoot the heavier/longer 200-240 gr bullets you should be able to shoot 180 just as well. The only issue that I have had with the lighter bullets is that you can get "stringing" with some powders. Especially if the powder does not fill the case. The best powders that I use for 165, 168, 175, and 180 sub-sonic loads are AA#9 and Alliant 2400.

Check out the Accurate Arms website. They have several sub-sonic loads listed for the 300 whisper/300-221 Fireball.

Good Luck

320pf

[justshoot]

great & Thanks . and I been using the #9 so far.
Its been working pretty good @ right around 9.2 grn./1025 fsp. with 220's
I will just load up a few 180's and keep it @ 9.2 to see what change in the Vel. will be.
.

[AlcoholicusMaximus]

I tested some 180gr Nosler BT's using 8.9gr AA#9 fired from a M1S 10.5" upper.
These rounds tumbled to the target, keyholed every last one. A buddy had the same results with a 16" Oly arms upper. It is strange to me that the 200gr & up will stabilize,but not the lighter bullets @subsonic.I do know the Nos.BT. has a pretty soft jacket. I really want the 180's to work,so I will try some SST's next.

[320pf]

Originally Posted by AlcoholicusMaximus

I tested some 180gr Nosler BT's using 8.9gr AA#9 fired from a M1S 10.5" upper.
These rounds tumbled to the target, keyholed every last one. A buddy had the same results with a 16" Oly arms upper. It is strange to me that the 200gr & up will stabilize,but not the lighter bullets @subsonic.I do know the Nos.BT. has a pretty soft jacket. I really want the 180's to work,so I will try some SST's next.

In the 300-221 fireball (aka 300 Whisper (r)) the bullets in the sub-sonic velocity regime tend to be critically stabilized (read just stabilized). This is particularly true for the long heavy bullets. The result is that if the velocities are too slow the bullets will wobble.

John Noveske referred another shooter to me who was having stability problems with 240 gr bullets. The shooters loads were unstable at 900 fps. I suggested that he increase the velocity of his loads. He increased the velocities and the bullets stabilized at about 1000 to 1020 fps.

The second possibility is... If the tip gets dinged/tweaked the bullets will also wobble. That is why bullets like the MatchKing and Berger hollow points bullets work the best in the sub-sonic realm, the tips are more resistant to being tweaked from riding up the feed ramp.

For example, I have shot Sierra 168 gr and Remginton 165 gr bullets for my sub-sonic loads and have not had this problem. Currently however, I am having a similar problem with some overrun 165 gr softpoint BT bullets that I picked up form Midway recently. I tried the following loads:

(The following were shot in a 1:7.5 twist 16-inch stainless steel Noveske barrel)
7.5 g AA#9-800 fps this load key-holed

8.0 g AA#9-900 fps this load key-holed

9.0 AA#9-1150 fps. About 2 out of 10 of the hits showed a key-hole indicating that some of these shot tumbled as well.

I tested the feeding of these bullets and the lead tips are getting deformed when they hit the feed ramp. So I think that this causing the bullets to not so much as tumble but wobble in flight. I know that the polymer tips can get "tweaked" some when they ride up the feed ramps as well.

When I load the soft lead tip bullets to max velocities they seem to stabilize.

So here is my suggestion. Cycle some rounds through the mag and chamber and see if or how much the polymer tip is deformed. (Lawyer talk here... Take the appropriate safety steps while doing this)
You should also chrono your loads to see if you are getting your loads to about 1050 to 1100 fps.

Good Luck and keep us posted on how your load development goes


320pf

[Ron458]

I was reading this & I may smoth out the ramp like I do on my 50AEs/440 corbons & such. It would make for a clean ramp/jump into the chamber. Just a thought. Ron