At 54, i shot a .413 group and scared myself.
The SAAMI chamber drawing has zero freebore. The 47.52 MOA tapered throat (leade) starts at the chamber mouth at .290 inch diameter then about half an inch to .2755 inch bore diameter. Most bullets seated to a 2.8 inch COAL will jump no more than .010 to .015 inch into the lands.The 284 has a long freebore for a reason.
That reason is the firearms it was chambered for the Model 100, and Model 88.
You will typically find longer freebores in these due to the action being weaker than a modern bolt action.
The long freebore is an old trick to help keep pressures down.
Reread this post then noticed a flaw in the conclusion.You got (one?) sub .5MOA group with a bolt action sporter and that bullet, I'd say its time to STOP there, and enjoy it. Forget the "long throat" clearly its not a problem with that load
Well stated. Thanks.Perhaps I was not clear enough, it happens. What I meant by "stop and enjoy it" was not "stop now, thou hast found the Holy Grail and need never go on" but more of a "stop, pause a while, and get to know this rung of the ladder". See if its it a narrow ledge, or if its somewhat broader...
One teeny group only proves you shot one teeny group, and that's what I meant, stop there, and shoot more with that load to see if that teeny group is a fluke or average performance.