Gerard wrote:

"Tumbling bullets will usually be extremely destructive and this is an important reason why heavy monometal bullets should be avoided. A 180gr .30 cal monometal bullet is almost the same length as a 220gr jacketed bullet. It is barely stable in a 1:10" twist and, because it is less likely to shorten as much as a jacketed bullet on impact, will probably tumble on impact and result in substantial damage. The higher the impact speed, the more likely a mono will be to tumble. If, for example a 150 or 160gr mono is used in a fast .30 cal rifle, the damage will be less, despite the higher speed."

Gerard,

Since you know as much (or more) than anyone in the world about FN solids since you were the first to produce and test them in commercial quantities, can you explain somehting to me.

As you may recall, I have tried to recover your .458 FN solid in water buckets and failed to do so they had so much penetration. They perforated 4 buckets straight on, finally turned a bit and exited the side of a 5th plus a bunch of 3/4 inch thick plyboard I used as a back stop.

Why would a large caliber w SD .300 not tumble and a 30 caliber with SD .270 be unstable in a quicker twist?

Is the rate of deceleration to blame? (A high velocity bullet has more drag and therefore velocity loss than a slower bullet?)

There seems to be consensus among most of us who shoot monometals to drop down one conventional bullet weight when shooting these bullets so the overall length is no greater than the haviest bullet normally used in that caliber.

I did not know the smaller caliber very high velocity FN bullets were more prone to "tumbling" than the slower big bores!

Is that a fair statement?

I was certainly happy with your 458 GS and the North Fork FN.

Thanks for your reply.

Andy

Gerard, I have just had the good sense to read some of your prior posts, and realize now that your knowledge of projectiles is far beyond mine. I apologise for my too quick criticism above. Regards.
PS--I have just added your website to my "Favorites"

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I feel the shorter MRX180 will be a good thing for those wishing to load 308win(more powder space). The more open tip should assist better expansion at longer range at the more moderate 308win velocities.
I thinks some guys worry too much, and over analize things.
If offered a free hunt in Africa, where they provided 30/06MRX, I am rather sure, very few of us would be too focused on the hypothetical issues of the MRX.
I know I wouldnt be.Nor would I be if paying.

Returned yesterday evening from field testing and product evaluation in the Camdeboo area. Hard work, but someone has to do it.

Andy, my comment on tumbling was mainly in the context of expanding monos compared to lead core bullets but it holds true for FN and other solids as well, to a lesser extent. Alf is correct in his reply and one must consider that, with larger calibers, twist is less important as most (not all) are actually "over twisted" for the respective bullet lengths. Twist becomes more critical with medium and small calibers where the overturning moment that is generated on impact becomes much higher in relation to the stability factor. A bullet in transition from one medium to another is exposed to forces that do not exist when traversing one medium or another. Bullets with a rearward inclned CG are more prone to tumbling on impact and should start with a higher gyroscopic stability number. The only way to do this is to shorten the bullet or to increase the twist rate.

Steve, no apology is required and no offense is taken. I am sure I can learn from you in more ways than one.

How many hunters on this site have not recoverd a properly hit game animal of any type when using a TSX? I have shot plenty of animals with this bullet from coyotes to deer with not a single lost animal. I am not saying not to try other bullets it is loads of fun to reload and experiment with diffrent componets. I have no special interest in Barnes bullets other than they work well in my rifle. Are we spliting hairs just because we can? Or is there truly a real issue with the TSX bullets. I personaly can't justify doubling the cost for me to shoot and hunt to kill somthing more dead. Just a thought.

458Lottfan,

Perfection is everything, finding the right bullet is facsinating..........I've tried Gerards, which were extremely accurate, to TSX's, Woodleighs and everything in between.

Looking forward to trying Northforks ( hard to import to Australia) and Rhinos.

My last hunt in Namibia showed me that monometals might NOT be the answer.............

Alf and Gerard,

Thankyou both for taking the time to reply.

I have been traveling and just saw your posts.

I was one of the first people to test the 5.45 x 39 and experimental 5.56mm SS109 here in the United States on gelatin and live animals.

The folks I worked with at Aberdeen Proving Grounds and FN Herstal in Belgium both said a longer bullet was more stable than a shorter one if it was adequately stabilized.

These bullet designers specifically sited the moment of inertia as the reason, a longer bullet being more difficult to turn over than a shorter one.

To move the CG of both bullets behind the center of form thje Russian designers built in an air space behind the ogive and in front of the swaged interior that holds the 5.4's 20 grain mild steel core in place (B-50 Rockwell hardness).

the FN designers did similar manipu;laiton of CG by using a ten grain high hardness steel insert ahead of the lead core (C-70 Rockwell).

Despite both bullets high rotatinal velocity they turn over very rapidly.

I have often wondered if a B-50 steel core would not make a good material for an elephant bullet. SG of 7 or so for steel so about like copper. the lead sheath around these bullets core protects the bore. B-50 can still be impact extruded which is why the Russians use it in their steel core ammo.

Thankyou again both for taking time to respond.

Andy