PDA

View Full Version : Question concerning bullet rifling engagement.



model14
07-06-2009, 03:04 PM
I am the new BR HV shooter with the seemingly very accurate stock 700 VLS (except for bedding, and now a better trigger). I have been seating my bullets (as a starting point), about .010" into the rifling lands. I am going to starting backing this out in .005" increments to see if I can improve my group aggs (get into the 2's). I got to thinking about this and I realized I don't understand how backing away from the rifling can/will improve accuracy/consistency. It seems to me that having the fire formed brass shoulder against the chamber and the bullet ogive against the rifling as anchor points, would give the best chance of consistent bullet entry into the rifling. I have read many times that each rifle (and revolver) can be/is effected differently by seating depth. Perhaps one of you with experience would enlighten me. Thanks.

abintx
07-06-2009, 06:03 PM
I don't understand how backing away from the rifling can/will improve accuracy/consistency.

The barrel holds the mystery. Your job is to find out what it likes. Sometimes it likes to be snuggled into the lands and other times it likes to sit just on or a little off the lands. Try using .003" increments and see what happens. You've got to unravel what it likes! Each barrel is different. If you don't have it, get a copy of Mike Ratigan's book Extreme Rifle Accuracy and make sure use read chapters 12 and 13. :)

model14
07-06-2009, 06:06 PM
Thanks, my next order from Sinclair will include that book. I know what you say is true, I just am not sure why. I am cursed with wanting to know how things work.

jackie schmidt
07-06-2009, 10:38 PM
Since you asked this on the Bencrest Centerfire Forum, I will give you an answer that is brutally honest.

Your statement "improve my group aggs, (get it into the twos)", is totally unrealistic. I feel safe in saying that there is no Factory Barreled Remington 700 on the planet that would poccess that level of precision. Sure, you might accidentally shoot a "two", but agging that is an entirelty different thing.

You did not say what chambering you have. But that has a lot to do with the overall accuracy capability of a Factory set-up.

If it is a 223 or a 308, I would say that you could realisically look at achieving .400 accuracy on a regular basis.

That takes a lot of load development, the best in bullets, the best in bench equipment, plus a good set of wind flags.

Of course, any Rifle will shoot better when you do find what that ideal seating depth is. Your theory that the bullet and shoulder will hold the round true holds water untill you realize that Factory chambers are in no way "true" when speaking in terms of precision barrel work.

Most Benchrest set-ups shoot at their best when the bullets are touching the lands, or into the lands some. Most Factory Remington Chambers won't even allow a shooter to get there because of the long free bores. That is, unless you are using rather long bullets for the caliber.

The best thing to do is take your loading equipment to the range, set up a good set of flags, and start going in or out with the depth untill something shows promise. Then, shoot at least three 5-shot groups with that setting.

Remember, to achieve the kind of accuracy that you are looking for, you are wasting your time unless you are using wind flags.

To give you an idea how 'agging in the twos' looks, at the recent World Benchrest Championships, the vast majority of the shooters were no where near 'agging in the twos'. In fact, when looking at both Grand Aggregates, only seven shooters stayed under .300.

Sobering, huh.......jackie