Lands and Grooves, Crimps and ...?

[cipher]

I've been using Berger bullets with good success.  Very accurate and very consistant.  One of the things I've tried to do is load the bullets close to the rifling.  With my Handi Rifles, it was relatively easy to get a sense of where the rifling began and thus the seating depth. 

Recently, I bought a Rem 700 SPS Varmint in 243 and was surprised at how accurate it was out of the box.  I was using some of the rounds I had loaded for my 243 Handi.  These were not crimped and when I decided to use them in the Remington, so I reseated them somewhat deeper so that they would fit in the magazine.  This led me to wonder how to measure the distance to the start of the rifling on the Remington.

I also load for a 223 Handi and have been crimping those for some time since there isn't a lot of bullet in the case with some of the Berger VLDs (they seem like they might already BE halfway down the barrel when they're loaded) and because they would be less likely to shift in the case when I'm banging around on my 4 wheeler.  I've also found that 36 gr Hornadys - a short, squat little bullet - are extremely accurate out of the 223  ; they are crimped but they're quite a ways from the lands.  Hmmm...

OK.  I wasn't entirely sure why loading closer to the lands was better  , but it seemed to be the common practice, so I did it.  I just bought a Lee crimp die for the 243 and actually read the directions.  It seems that crimping is supposed to make for a uniform start pressure and a more accurate load. 

So, maybe this explains why the 36gr Hornadys were so accurate.  Maybe I don't need to seat the bullets close to the lands if I'm crimping and thus the crimp die solves my problem.

Anyone have any thoughts on this?  Do you crimp?

Thanks,
Paul

[Lone Star]

Experimenting with different seating depths is just one part of tuning a load for accuracy.   A lot of handloaders like to set their bullets close to or touching the lands because that is what benchrest shooters do to get their tiny groups.  The reality is, some barrel/bullet/cartridge combinations will shoot best with the bullet touching the lands, some with the bullet close to the lands, and some with the bullet a ways away from the lands.

Take Weatherby rifles for example, they have 3/8" of freebore and it is almost impossible to seat the bullets to the lands.  But, many of them shoot very well - sub-moa - with a long jump to the lands.  I have an M700VLS in .260 Rem that shoots better with the bullet 0.08" off the lands than it does with the bullets almost touching.  My advice - worry more about the bullet falling out of the case when transporting the ammo than trying to get short bullets close to the lands.  You may find that accuracy is as good or better with a little morre bullet left in the case.

IME crimping almost always reduces accuracy in bottlenecked cases.  Lee's instructions are there to help sell more factory crimp dies.  Lee and Speer even got into a big argument in their advertisements on this very topic a few decades ago....


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