Stan de Man, like your name!
Welcome!
You have a couple of issues you need to be aware of, if you are not already.
1. magazine length vs OAL with the bullet touching the lands. I am sure you are aware that
bullets have their own mind in how they like to be seated for best accuracy. You will not
be able to chase the lands, and you are pretty much stuck with an OAL. Many people find
that their barrels are shot out when they can not get close to the lands. It is possible to
tune a load with the bullets jumping, but more often than not, it will require you to make
a compromise in accuracy. For instance, you may wish that your rifle shot 3/8" and you may
have to settle on 3/4" due to bullet design vs mag length.
2. concerning the 53g V max, it likes to be seated close to the lands. You have a good bc on
this bullet, but it is finicky in terms of how it is seated in relation to bullet jump.
3. Barnes bullets like to jump, often a lot. Start off with a .050 bullet jump, this maybe your
best bet.
Stan, you are at a cross roads in decisions. Bullet jump vs oal is a serious issue. You should not use your gunsmith's options. Find your own barrel, and it sounds like you want a 1-8 twist. The 75g A max and eld are great bullets in the 223 AI, and you would be in hog heaven if you could chase the lands with this bullet. 69g tipped MK is great also, but again what kind of accuracy are you wanting.
You ask for advise, and these considerations on OAL, Mag length, and twist rate with particular bullets is where I would solve the problem first. This may require the purchase of another action or rifle, but work toward achieving your accuracy goals, and I think that you should be hard headed in staying focused on shooting the 75 and 69g tmk in an 8 twist. The fact that you can get thousands of very accurate rounds IF you have the ability to chase the lands as the leade grows is of paramount importance. If you do not take into consideration the OAL vs magazine length in your build, you maybe in for some great disappointments in as far as accuracy with various vld type bullet choices.
I am a 223 Ai freek and shoot the 50 & 53g at 3850 and the 55's at 3750 in 12 twist barrels.
If you can take your time on the project, you may want to consider actions with longer OAL's for magazine use....this is where I would start, which would require you to push the reset button on your project.
I have no idea what your use for your gun would be.
Spending the money on a custom barrel is expensive, and I have learned some hard, expensive lessons. One of these lessons is that long range shooting over a period of barrel wear requires long magazine boxes. Many barrels will shoot well when they are new, and owners tend to think of how their barrel shot when it was new, being in total denial as to how the accuracy degrades 1500 rounds later. To not have a long magazine box requires a "barrel set back" and depending on the taper you use, your gunsmith may not be able to do a set back which would demand a new barrel....all due to poor planning which hurts.
Accuracy is a relative thing, people think differently and a persons wants and wishes can change over time. I think in terms of shooting an inch at 300 yards, which is nothing special for a custom barrel if done properly.
Below is a target shot out of a 23" Hart 14T shooting the Nosler 55g at velocities between 3700-3750 with various loads, The barrel is on it's 2nd chamber and I am working up test loads
for the new chamber. The barrel had around 4000 rounds on it prior to the barrel set back, where 2" were cut off the barrel. The barrel shot the 55g Nosler varmagedon a tad better, but I did not save the target.
On the target, you can see how the wind is shifting the group impact around, the sight settings were NOT adjusted. I had out a wind flag and was doing my best to shoot as I picked a direction.
[/URL]
Here is the group shot with the 50g speer tnt and the 50g nosler BT shoots just as good, 300 yards. This is meant to illustrate how COAL in relation to the lands has a dramatic impact
on accuracy. These groups are TYPICAL for custom 223AI's and should not be considered exception by any means. The action is a non trued remington 700.
[/URL]
50 and 55g Nosler Ballistic tips are fantastic coyote killers.
In a 12T that I have, the 53g Vmax is doing 3800 with 28g of H338, long barrel life is guaranteed!
Also, I shoot a 60g Nosler partition at 3400, and it makes a mess out of a deer. The last 100 lb doe I shot through the shoulders, I had to throw away the entire front end of the deer...looked like it had been shot with a 150g out of a 300 Winchester Mag.
My friend shoots the 75g A max at 3150 out of his 223 AI with a 23" 8T Krieger barrel. Accuracy is astounding to say the least, but I don't think that his load kills coyotes as good as the 55's at 3750.
Stan, it is a lot of fun building and planning a rifle build, worst mistake you can do is to be in a hurry. Take your time, do it the way you want it, and making compromises will be a focus of regret as time goes on.
Good luck and best wishes, again welcome to this site one of the best on the net.
