28 Nosler...

[Deleted member 46119]

Hey Fred, any updates to report on those LRXs? Hopefully things all worked out for you in regards to loading and shooting these new rounds.
Thanks for all your work and willingness to share your findings with us!

Been busy. Work and a little play fixing an old rolling block for a friend.

The bullets are on the bench waiting for me.

 

[Deleted member 46119]

Ok, got the testing done. Too late to type in all the data but...

The "Tubb's Final Finish" did speed up my barrel.

Speeds are now inline with QL predictions. However pressures are high. Go figure.

I'll get the data typed in tomorrow.

 

[bb204]

What length test barrel are you using ? What velocities do you think could be expected from a 24" barrel ?
Thanks,

 

[Deleted member 46119]

What length test barrel are you using ? What velocities do you think could be expected from a 24" barrel ?
Thanks,

Mine is 24"

 

[bb204]

Would a 28 Nosler reamer clean up a 7mm Rem Mag chamber ?

 

[Edd]

If the 7mm chamber is a SAAMI spec chamber and if you use a 28 Nosler SAAMI spec reamer, yes it will.

 

[Wachsmann]

So how does the 28 Nosler compare to the 7mm-300Win? I looked around and what I could find both cases have the same H2O capacity. Is the 28 better in design at using the powder, more burn efficiency, pressure curve, does it have a longer neck to hold the bullet, etc, etc, etc. Are both cartridge able to produce the same velocities with the best of powders for case design? Example might be if the 7-300 uses retumbo to produce the highest velocity and the 28 Nosler uses H1000 for its highest velocities. Would the two be very close to equal like within 25 to 50fps? Thanks.

 

[meatyrem]

What it is I don't understand is how a case made off from another case (7mm Rum) with base and shoulder diameters around the same if not exactly the same within a couple thousandths and with the case being shorter by approximately 1/4 of an inch and a case capacity roughly 15 grains less. How is it the 28 nosler can come out way ahead that the 7mm Rum? Some times fairly even and other times way out in front by over 100fps sometimes. This is where I get confused. Same barrel length and from the nosler manual too. Are they being real optimistic with this performance?

 

[Edd]

So how does the 28 Nosler compare to the 7mm-300Win? I looked around and what I could find both cases have the same H2O capacity. Is the 28 better in design at using the powder, more burn efficiency, pressure curve, does it have a longer neck to hold the bullet, etc, etc, etc. Are both cartridge able to produce the same velocities with the best of powders for case design? Example might be if the 7-300 uses retumbo to produce the highest velocity and the 28 Nosler uses H1000 for its highest velocities. Would the two be very close to equal like within 25 to 50fps? Thanks.

A 28 Nosler is going to have about the same case capacity as a 7mm STW. A 7mm-300 Winchester is going to be smaller.

A 28 Nosler has a slightly longer neck than a 7mm-300 Winchester but I still consider it short.

 

[Deleted member 46119]

Would a 28 Nosler reamer clean up a 7mm Rem Mag chamber ?

Yes it will.

 

[Deleted member 46119]

So how does the 28 Nosler compare to the 7mm-300Win? I looked around and what I could find both cases have the same H2O capacity. Is the 28 better in design at using the powder, more burn efficiency, pressure curve, does it have a longer neck to hold the bullet, etc, etc, etc. Are both cartridge able to produce the same velocities with the best of powders for case design? Example might be if the 7-300 uses retumbo to produce the highest velocity and the 28 Nosler uses H1000 for its highest velocities. Would the two be very close to equal like within 25 to 50fps? Thanks.

It's more like 10 grains difference and 100fps.

 

[Deleted member 46119]

What it is I don't understand is how a case made off from another case (7mm Rum) with base and shoulder diameters around the same if not exactly the same within a couple thousandths and with the case being shorter by approximately 1/4 of an inch and a case capacity roughly 15 grains less. How is it the 28 nosler can come out way ahead that the 7mm Rum? Some times fairly even and other times way out in front by over 100fps sometimes. This is where I get confused. Same barrel length and from the nosler manual too. Are they being real optimistic with this performance?

I'm sure if ballisticsians could could answer that question really well we'd have fewer chamber designs.

It does seem to be true.

Not so true with the 300RUM vs 308/26-Nosler or 338s.

 

[wilkup]

Ok, got the testing done. Too late to type in all the data but...

The "Tubb's Final Finish" did speed up my barrel.

Speeds are now inline with QL predictions. However pressures are high. Go figure.

I'll get the data typed in tomorrow.

So...
What were the numbers after its all said and done?

 

[Deleted member 46119]

24" test barrel. This barrel is "slow" but faster since doing a "Tubbs" treatment. A higher quality barrel should be faster by 50 to 100fps.

Load data
Bullet: Barnes LRX 145
COAL: 3.460
Powder: IMR 7828
76 grains, 90% case capacity, 3221fps, psi
77 grains, 92% case capacity, 3280fps, psi
78 grains, 93% case capacity, 3300fps, psi
79 grains, 94% case capacity, 3320fps, psi
80 grains, 95% case capacity, 3335fps, 58705psi
81 grains, 96% case capacity, 3387fps, 59494psi
82 grains, 97% case capacity, 3417fps, 62992psi