Hammer Bullets and twist recommendations

HARPERC

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For most of my hunting/shooting life I assumed the barrels I ordered were as designated. Mostly cup and core din't challenge this assumption.

Entering the world of mono's I've seen many twist not as advertised, and default to choosing a faster option.

From a hunting standpoint I've yet to see a mono over spun, or driven too fast.
 

ButterBean

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For most of my hunting/shooting life I assumed the barrels I ordered were as designated. Mostly cup and core din't challenge this assumption.

Entering the world of mono's I've seen many twist not as advertised, and default to choosing a faster option.

From a hunting standpoint I've yet to see a mono over spun, or driven too fast.
X-2
 

Wedgy

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So a little more information about stability/instability as I understand it. The distance between the Center of Pressure (CP) and the Center of Gravity (CG) in a given bullet is what creates the overturning moment arm that induces instability. The center of pressure is the sum of the aerodynamic forces (drag), air pressure or vacuum, created by the bullet when passing through the air. The exterior shape of the bullet directly affects the CP and it's location on the bullet centerline axis. Ideally, one would want to get the CP aft of the CG for max stability; for all commercially available bullets I'm aware of, it's not. If CP was aft of CG, Barrel twist rates could be reduced (i.e. 1 in 20") to decrease drag in the barrel and achieve higher velocities. The conflicting requirement is how too create enough drag at the back of the bullet but not impact BC too much.

Please don't assume my knowledge of guns, shooting or hunting is greater than anyone else's. I just try to keep learning whenever I can and share when I think it might be appreciated.
Yes, that's what an arrow does with fletchings, more drag at the back and a slight rotation as well, but no barrel resistance is involved.
I was an RSO at a 2 mile range that was testing guided bullets for Raytheon, like the fins on guided missiles, but they couldn't overcome the ~300K RPM bullet spin to make the guide fins work. Not sure whatever happened to the project.
 

GLTaylor

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Since most of us aren't rocket scientists, the only guidelines we have are stability factor.
Calculate your SF using JBM or Berger's stability apps. 1.5 is the old standard for stability IN FLIGHT through air. We are learning that this may be minimum for monos (Hammers). A SF of 2.0 or more is better! This is especially true when it comes to stability at impact and the need for straight line penetration!
 

ButterBean

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Since most of us aren't rocket scientists, the only guidelines we have are stability factor.
Calculate your SF using JBM or Berger's stability apps. 1.5 is the old standard for stability IN FLIGHT through air. We are learning that this may be minimum for monos (Hammers). A SF of 2.0 or more is better! This is especially true when it comes to stability at impact and the need for straight line penetration!
I concur
 

FEENIX

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While a bullet will stabilize in the air, marginally, when that bullet hits game the stability really erodes and will tumble or have erratic performance.
A faster twist delivers a terminal stability inside the game. So in short do not discount the recommended twists
LOL, I do not think I could have made it any simpler and straight to the point as #2.
 

12gaugeman

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I could be wrong - I usually am - but I believe it’s the length of the bullet’s bearing surface, not the overall length of the bullet, that commands a minimum twist rate?
 

Zorack

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After hearing and seeing so many successes with the hammer hunters I thought I might get a couple boxes for a couple of my rifles. As I was perusing their products I was noticing that they recommend a very aggressive twist for bullets that aren't even at the heaviest side of the spectrum. Particularly for the hammer hunters. Any reason for this? Can anybody share their experience with working up loads? I've ran 20-30 gr heavier bullets with the twists they're recommending for their lighter ones. I've looked across all of my reloading manuals and none of them are recommending barrel twists quite this aggressive. I tend to always prefer the heavier bullets and the weights I typically love to run are showing a twist that none of my rifles have...at least according to Hammers recommended twist.
If I'm correct, a lot of it has to do with the length of the bearing surface of the bullet. Since solids tend to be on the longer side.
 
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