Does the first shot out of an oiled bbl give a higher or lower reading for you ? What does the second shot do ? I shot my .358 a few days ago and the first shot was a low reading, the second was very high But the next five were within 13 fps of each other. Think I might have screwed up somewhere ? Also the choronograph is giving much higher vel readings with my loads in 20" bbl Than the same loads listed in most books with 24"bbls seems strange to me.

Believe your chronograph before you believe manuals.Manuals can be up to a couple of hundred feet per second off due to variances in barrels and components.

Ive had that SAME thing happen 358.
I have an idea but it is a pure guess.The first shot slips down the barrel with little resistance,which would lower your pressure and velocity.The second shot has to run through burnt oil and gunk,raising pressure and velocity at the same time kinda cleaning out the barrel a bit.Then the following bullets have a consistent barrel friction leading to your narrowed numbers.I am speculating, this is not a fact.(my own disclaimer)From now on i run a couple dry patches to get most of the oil out.

Never-Never-Never shoot through a barrel with oil in it. You can ruin the barrel. A know it all buddy now has a nice ring in the barrel of his Rem.700. Never shoot with oil in the chamber either! The cartridge case can't properly expand and will slam the bolt face with much force. Accuracy goes down the tubes in a hurry. Run a few dry patches though the barrel and chamber before firing any firearm.

I TRY TO ALWAYS dry any oil out of a bore and chamber before firing a round. However, that said, it is entirely possibel (LIKELY, EVEN!!) that your first shot from a clean barrel will perform differently than succeeding ones. Col. Townsend Whelen used to talk about what he called "the sniper's zero", by which he meant that a rifle should be zeroed so the first shot from a clean or cold barrel would be the one that hits dead on, because this first shot is not only the most important one, it may be your ONLY one!! Where I have been hunting recently, in the Adirondacks, this idea certainly applies!!

Thanks, what you guys say makes a lot of sense. Appreciate the imput.

As mentioned above, If you clean your gun before a hunt, it would be a good idea to know where that first shot from a clean barrle hits. Having said that I must say that although I have many times noticed that the first shot will often read out diffeerent than following shots, I have never seen much difference in the point of impact on a string of shots up to about 5 or 6.

Before I go into the field (hunting) with a clean barrel I always take a couple of fouling shots to season the barrel to insure accuracy.