6BR seating depth on shorties

[jefats]

I have read/heard that you should seat bullets such as to have the neck making contact for at least a full caliber length along the shank, i.e. .243" for 6MM bullets. This includes boattail bullets as well as flatbase designs.

I have always had the best luck/accuracy seating bullets as close to the lands as possible but in doing so, there is precious little shank being gripped on a lot of bullets.

I'd be interested in hearing opinions and experiences of forum members on this subject.

Thanks

 

[NorCalMikie]

One of the bad things about factory barrels is most have a pretty long frebore.
That's why,when I order a barrel I get it chambered to my dummy round. I want my bullets stuffed all the way down to the shoulder/neck junction. As the throat wears, it will only get longer. Seat your bullets deep and you can pull them out of the case a bit to reach the lands.
I've never seen a chamber throat get shorter.
I prefer as much bullet in the neck as I can get.
Start off with 50s, go to 60s, then go to 70s. Start off with 100s and you're just about of barrel.

 

[RJinTexas]

Jim, the bullet dia seating depth rule of thumb applies reasonably well for hunting rounds. I've never had a problem with as little as one half of the bullet dia being seated when single loading for shooting competition. But with that being said NorCalMikie's idea of sending a dummy round to have a reamer made that will allow you to seat the bullet you've chosen to shoot as deep as possible without having any of the bullets bearing surface below the neck shoulder junction and throated where the bullet just touches the lands will provide you longer use of the barrel without rechambering because you can chase the throat errosion.

RJ

 

[Forum Boss]

I like to have at least .180 of bearing surface in the neck on a 6mm bullet. But we have shot some pretty amazing groups with Berger 95 VLDs with only about .120 of bearing surface in the neck and .0015 neck tension in a no-turn 6BR case. So... who knows. It's worth experimenting.

 

[Steve Blair]

I feel the same as our Forum Boss, Mike and RJ about neck engagement. But, if it is a single shot rifle and you handle the rounds somewhat carefully, it should not be a problem. If feeding from a magazine, I prefer to have as much engagement as possible, consistent with accuracy goals, and a little more tension to hold the bullet securely.

 

[NorCalMikie]

Even with the bullet just about falling out of the case neck on one of my first "long throat" 6BR barrels, the accuracy was unbelievable. 8)
What it boils down to is plan ahead before you spec you chamber.
And if you don't use a dummy round, my guess is that most of the barrel makers have a real good idea what freebore to cut for the bullets you plan to use.
The dummy round just happened to work best for me.

 

[jefats]

Thanks all for the thoughtful replies.

Let me pose another question: On single shot (Target type) rifles with long throats, is there any downside to seating the shorties out as far as possible, maintaining just enough shank engagement to hold the bullet firmly while still not touching the lands?

 

[hogpatrol]

In a 1-14 twist 6BR using Precision Ballistics 68gr flat bottom, .005 ITL leaves me .170 inch in the case neck. Just started shooting this gun so haven't had time to experiment with jump loads but first session at the range, the groups were less than 1/2 inch @ 100 yds. using N135, CCI450s & new Norma brass. Chamber was done with the bluebox .270 .093FB reamer.

 

[NorCalMikie]

All my rigs are set up as single shots. Either ss actions, ss followers added to the mag or ss sleds. All of them are short throat chambers. I still like as much bullet in the neck as I can get. Gone from 40s, to 50s and now up to 60s as the throat wears.