COAL confusion with my LTR 308

[SigScirocco]

Back again to ask the experts

From everything I've read, COAL is important in obtaining accurancy in any rifle. I've purchased the Hornady OAL gauge and determined the COAL for my Remington LTR with A-Max 168gr to be 2.950 taking into account the 20 thou gap between the bullet and the lands of the barrel. This set up was very accurate......as long as you only used one cartridge at a time. The LTR will only allow a maximum COAL of 2.840 due to the hinged floor plate internal dimensions (lenght). Would a magazine allow for longer COAL, like with the Tikka Tactical? Is it true that a COAL shorter than 20 thou off the lands will be less accurate? Is there a way to increase the internal lenght of the LTR to allow longer COAL? Am I being to picky and should I just follow the books by reloading to a max COAL of 2.810?
Thanks for your input.
Shawn

 

[warrenb]

With regard to your mag length, make them fit and adjust your charge to get the best accuracy. It may work out as good as 20 thou off the lands, it may not. So far as I can tell, the only way to know where a particular bullet really likes to be seated, in a particular gun, with a particular powder/charge is to use up barrel life trying every combination out.

 

[rnbra-shooter]

You can find out by testing some ammo loaded to 2.840" whether or not you get accuracy as good as you get at 2.950". If you do, then problem solved. If not, there are a few things you might try to get good enough accuracy with magazine length ammo:
- as warrenb suggests, charge weight tuning might help (I wouldn't fiddle around with minute tuning. Try half grain or even full grain steps. Be ready to abandon this route before wasting too much time on it, either it will show promising results early or it is likely not going to be too terribly helpful)
- try a different bullet that is "known" to be fairly tolerant of large amounts of jump (for example I've found the Berger 155.5s to be pretty good in this department)
- try a bullet that has its shank farther forward, so that you are closer to the lands even when you are restricted to 2.840" or less. The problem here is that you might be taking some otherwise really good match bullets out of consideration. (sorry I can't think of any good bullet recommendations off the top of my head)