Free bore and COAL

[Splat]

I've been trying different bullets and it doesn't look like I will be able to load any of the bullets that I've measured very close to the lands in my AIAT 308 due to free bore. The mag length is 2.98" so I COULD load the 168gr SMKs to the lands but it leaves very little of the bullet in the case neck (.13-.15"). I've measured Berger 185gr Hybrid Target, 168gr SMK, 178gr AMAX and 168gr TTSX BT so far. To load within .005 from lands only puts .13-15" of the bullets rested inside of the neck with with tension. . The pic is a Berger 185gr hybrid target measured to the lands.
I've only been reloading for a couple of years so I'm somewhat new to it and my question is... Is it safe to have so little of the bullet with tension or will it just be a matter of runout? Anyone else measured the same bullets in their AIAT with a comparator?


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[dauntedfuture]

That's what you will usually get with a factory throat. The Brits are concerned about possible excessive pressures with their rifles to the extent that when you take a rifle there to shoot in some of the INTL matches they will check the throat and chamber dimentions and if its too tight they will ream it out right there or tell not let you shoot that rifle. Long throats yield less pressure. All this said the 168g bullet is NOT pickey about jump so there is no real reason to get it .001 off the lands. The 175 sierra and most other non VLD bullets are fine with some freebore. You might have less luck with the berger 185 but I don't know all that much about it. Try seating them well into the case so there is at least .30 of bullet full diameter in the case and go and shoot. I loaded some .155's very very long to the point that there was about .20 in the case in a factory varmit gun and they shot well but are more prone to damage.

 

[morganlamprecht]

Amax's and SMKs dont care much...i load all mine to 2.810" overall and have no problems finding consistent loads in all my guns

 

[Splat]

Thanks fella's. I just loaded some Berger Hybrid 185's to 2.82" I will see how they shoot tomorrow. I guess I will load up some of the AMAX's with Varget and test those out also. I'm wondering if I can get a 260 barrel with a little tighter chamber for it.

 

[Woj8541]

Most tangent ogive bullets actually shoot better when jumped, and even when significantly jumped. Load that stuff to .080 under mag length, find your node then work back and forth about .040 increments longer (until mag length) and shorter. You'll find it pretty quick. Also, pull out the spacers in your AICS mags if you need extra room. Just drill them out on a press.

 

[KYpatriot]

Most tangent ogive bullets actually shoot better when jumped, and even when significantly jumped. Load that stuff to .080 under mag length, find your node then work back and forth about .040 increments longer (until mag length) and shorter. You'll find it pretty quick. Also, pull out the spacers in your AICS mags if you need extra room. Just drill them out on a press.

This post is exactly right. I have a stock factory remington 5r that has lots of groups in the .2s and .3s with 175smks, and it is jumping well over a quarter of an inch! Dont worry about it, it will shoot. Berger hybrids will jump just fine as well.