Berger 105 hybrids in a 8 twist?

[savagedasher]

To say a 1-8 twist 6mm barrel is fast enough twist for the 105gr Hybrid is like saying that all the new findings from Brian Litz book is wrong and the new long hybrid style bullets can't benefit from a stability factor greater than 1.5...

I can say my 7-5 barrels shoot better at 1000 in our normal winds. Paper tare hole is better also . Larry

 

[Dusty Stevens]

This time next year itll be common to use a 7 or 7.25tw now that everybody will be looking at those huge holes in their target and remembering this topic

 

[dreever]

The 105 hybrids work fine in both my .243s to 1k. Kreiger in one, Bartlein in the other, both 1 in 8 twist barrels. Elevation changes match QuickTarget predictions, so they work for me. MV is at 3kf/s with both rifles, range elevation is around 350 feet. I found the last batch of 1500 to be shorter than nominal, and meplat trimming average out into two length groups, 1.322" and 1.332".

HTH,
DocB

I tried them in my 8 twist 26 inch Kreiger but went back to the 105 VLD Hunting which were more consistent grouping. My reamer cuts a pretty short throat so I think that may have been a factor.

 

[dkhunt14]

I tried them in my 8 twist 26 inch Kreiger but went back to the 105 VLD Hunting which were more consistent grouping. My reamer cuts a pretty short throat so I think that may have been a factor.

This is what I saw also. My throat is .155 so I don't believe your throat was the problem. Matt

 

[dragman]

Like Matt said I have seen MANY shoot out at 1000 and have a LOT of success (as long as it wasn't too windy). On another side I have seen some guns just not be able to get the 100 yard groups in the zero's and 1's with the hybrids while they could with the VLD's.

 

[CubCouper]

A stability calculator is a rough estimate at best. Look at the numbers it produces for a 6PPC and you'd think they would lucky to shoot a 2" group. The formulas in those calculators go back to the 1930's and were derived to help the military spec designs for wartime weapons. There have been a few enhancements of the original formula, but the root is still the same. Manufacturers would tend to prefer over-stabilized bullets because it is less risky for them, but it doesn't mean that a faster twist is better.

In all actuality, your reamer design, throat wear, and control of seating depth probably has more to do with whether it will shoot or not than the barrel twist. If you compare three bullets: the Berger VLD and Hybrid, and the Sierra 107 you see three completely different profiles. The VLD is has secant ogive, a Hybrid starts as tangent ogive at the body but transitions to a secant ogive (hence 'hybrid'), and the Sierra is a pure tangent ogive design. A secant ogive shape implies a slightly sharper change in profile than a tangential design, so these factors make a difference in how the bullet contacts the rifling. The variations are extremely tiny and probably change with barrel wear. I've had 8tw barrels cut on the same reamer that show definite preferences in all three designs. Do a little load development with each design at couple seating depths and you'll find a sweet spot if it is in the rifle.

Rod

 

[Judd]

My last 3 barrels have been 8.5 twist and shooting the hybrids competitively...if I miss it isn't the barrel, it's me. Also, I don't have anywhere that we shoot over 500m competitively. That's approx. 400 foot above sea level and pushing them 3020-3100fps.

 

[dkhunt14]

I wonder what accuracy requirements are being considered. I am needing to shoot 5 or 10 shots in the 3 to 4 inch range on a good day to win in 1000 yard BR. I also wonder how many checked their twists to see if they actually were an 8. Matt

 

[dragman]

I wonder what accuracy requirements are being considered. I am needing to shoot 5 or 10 shots in the 3 to 4 inch range on a good day to win in 1000 yard BR. I also wonder how many checked their twists to see if they actually were an 8. Matt

I also wonder this, people me included some times spend thousands and thousands and sometimes over look checking the simplest things because we just assume they are what they are supposed to be.

 

[Judd]

I've not checked them...I haven't had a need to but I get what your saying.

As for the accuracy, we shoot 7/8" poker chips @ 200y to mini clays at 400y...I'd say that is the two toughest I shoot. I'll also say that a 2" group at 500m does me no good if I don't know where it will shoot it all day (meaning if it moves around a bunch, I won't be competitive).