New 220 Nosler BT' Range Report... Problems.

[willis]

a one in seven spins slower than a one and ten ??
Willis.

[dellet]

There is something about all of this that I do not understand.
The above states that these bullets are "designed for subsonic use". How do you know that ?? And if they are,why do they have a boat tail ??
Back to my above . . . someone please fire some of these in a 10 twist 308 at 2500. I would really like to know why these bullets are tumbleing IF NOT for the extremely slow forward and rotational velocity. --- pruhdlr

From Nosler bullet descriptions,
https://www.nosler.com/ballistic-tip-bullet/

The bullet was designed for the Noveske 220 Ammo buy Nosler
http://shop.nosler.com/nosler-ammunitio ... count.html

I can probably test those anywhere from 50-175,000 rpm in this cartridge. 1/5@1250 fps=180,000 SG 6.65. 1/10@750 fps=54,000 SG 1.539. An SG of 1.6 is considered optimum, 1.2 is very marginal.

Going by bullet length and weight, which is what most stabilization calculators do, That bullet should have stability at 900 fps in a 1/10 twist. I have shot plenty of longer bullets past 200 yards in a 1/10 and they are fine. Bullet shape does make a difference and this one is as about as aerodynamic as a loaf of bread.

Looking at the bullet, it will need to be loaded pretty short to stay out of the lands. That means compressing powder is a possibility. It also has a nose shape that may not be friendly to a normal .308 seating stem. That's why I wonder if it's not a loading error causing bullet deformation or alignment issues.

It might be a fun bullet to play with just to see what it does at 200 yards in a /10, but I owe a few people some testing that I did not get done this winter, so for me it will have to wait.

[Klem]

A lot of people have had trouble with them. First thing I would do is physically check twist rate of the barrel. Then start at 10 yards to check stability, then you will know if it's ever stable.

viewtopic.php?f=141&t=101041

Thanks dellet, this is what I am looking for. Also probably why the guy at Nosler asked for my data when I queried them about it. I gave it to him but he is yet to respond.

The Miller stability formula has them way over-stabilised in typical fast Blackout twist rates. Much better stability from slower 308 twist rates. I would not be surprised if Nosler publishes a cautionary caveat on the spin RPM. Just like LeHigh did with its 78gn CQB bullet (but not before it damaged my suppressor).

I have loaded some more and will test them shortly.

[ozleux]

I've been thinking of giving these another try once the weather warms a bit. Not in front of my notes, but I do remember they were more stable at the shorter lengths.

[dellet]

A lot of people have had trouble with them. First thing I would do is physically check twist rate of the barrel. Then start at 10 yards to check stability, then you will know if it's ever stable.

viewtopic.php?f=141&t=101041

Thanks dellet, this is what I am looking for. Also probably why the guy at Nosler asked for my data when I queried them about it. I gave it to him but he is yet to respond.

The Miller stability formula has them way over-stabilised in typical fast Blackout twist rates. Much better stability from slower 308 twist rates. I would not be surprised if Nosler publishes a cautionary caveat on the spin RPM. Just like LeHigh did with its 78gn CQB bullet (but not before it damaged my suppressor).

I have loaded some more and will test them shortly.

What is you data?

Can you check run out/concentricity ?

Over stabilization, at least in this cartridge is a bit of a myth, at least with jacketed bullets. I used a 24" 1/6 barrel for a year on a Remington 700. I could not push any bullet fast enough to get it to show a wobble on paper. the best I could do was to see a 3/4 MOA group at 100 open up to 1.5 MOA. Balance MIGHT have been the issue opening them up. Tuning a load was more difficult. For the most part we're talking spin rates in excess of 260,000 rpm. bullets in the 150-175 range. 300,00 for 125's and 325,000 for 110's.

Powder choice can make a difference with some bullets. I had that 78 CQB bullet coming apart in a 1/9 at 210,000 rpm but staying together in a 1/5 at 340,000 rpm. If pressure builds too high too fast, it came apart before it made it all the way into the bore. The bullet is just too fragile and angle of the leade into the bore could also be a problem.

Nosler probably used a thinner jacket on this bullet to get the low expansion threshold. If that's getting damaged, it would explain a lot of the problems.

[dellet]

I've been thinking of giving these another try once the weather warms a bit. Not in front of my notes, but I do remember they were more stable at the shorter lengths.

Nosler has data on their site now. Suggested COL is 2.100". not really any compressed loads shown.

Knowing what length this bullet jams would be good information.

https://load-data.nosler.com/nosler-loa ... -220gr.pdf

[ozleux]

I've been thinking of giving these another try once the weather warms a bit. Not in front of my notes, but I do remember they were more stable at the shorter lengths.

Nosler has data on their site now. Suggested COL is 2.100". not really any compressed loads shown.

Knowing what length this bullet jams would be good information.

https://load-data.nosler.com/nosler-loa ... -220gr.pdf

I'll check when I get to the house, and let you guys know.

[ozleux]

2.125 in an AR
2.380 in McGowen 700 barrel

[bearcatrp]

Are these bullets rated for the 300BO? Box states 308. Glad I decided on the Hornady 190 sub. Works very well with no key holing.

They are a .308” 30 calber bullet designed for subsonic use. Doesn’t really matter what brass is behind them.

It would be good to see your 100 yard targets with the Hornady bullet. If it has less stability issues it would be great.

I zero'd mine at 50 yards. No key holing. Hope to get to the range this weekend. Will shoot a few @100 yards to see how they do. I try not to shoot to many as these are not cheap. When I talked to hornady last month about this bullet, I asked when they will sell just the bullet. Was told at least 2 years. Am hoping he is wrong. From all the tests I see online, the 190 sub is doing very well as advertised.

[dellet]

2.125 in an AR
2.380 in McGowen 700 barrel

I believe that's a problem, 1/4" difference in throat, The AR measurement is more what I would expect with that bullet.

Can you measure base to ogive on the bullet?

If not, if you have a 220 or 240 SMK see how long you can seat them. Should be around 2.270"