Bullet Seating Depth Concern

[jonas111]

I have a Sako IV in 270 caliber and I was using a friends bullet seating depth tool and I found out that if I back the Barnes TTSX off the lands .050" the bullet barely fits in the clip.

If the bullet is more the .100" off the lands does this cause any damage to the gun? Will it still shoot fairly accurate being .100" off the lands.

Factory amo is about .220" off the lands.

 

[ben hunchak]

There is no safety problem, if everything else is right, seating the bullet just off the lands is where alot of folks find they get best accuracy. I'd load 'em to the length that they will fit in the mag. and if you're not happy with accuracy, try a diff. bullet.

 

[Silverback]

Most people want their bullets just off the lands for greater accuracy, it usually helps but not always. In a hunting rifle the problem with magazine length is quite common, your 0.050" off the lands loads are probably over maximum length for the 270. It won't hurt the gun at all if you load them 0.100" off the lands, just make sure that they will reliably load from the magazine before hunting with them.

 

[lthunt]

lee factory crimp

i have found that in some rifles if i use a lee factory crimp die my accuracy is as good when i jump the bullets as it is when i load close to the lands.My rem 700 in 270 win has a long throat but i load to proper length because some of my buddies also shoot 270 and if i load long to fit my chamber it will not function in there rifles or feed in most mags.Reliability Is the most important part of reloading hunting ammo

 

[flick]

^ Interesting observation. I've got a collet-type neck sizing die that gives me less than .001" of neck tension, and I had wondered how a lee factory crimp die might affect accuracy. I'll try it before I turn down the mandrel in the sizing die at least.

 

[fatrack]

Those Barnes triple shocks are one of the exceptions to the rule of "better accuracy closer to the lands"- they need more seating depth to get accuracy. If you have a hard time getting them to shoot, seat them deeper.

 

[Cinch]

It's been my experience and many others that the TTSX like to jump, I have always started my load development at 0.050" off the lands.

 

[rookie wildcat]

i have found that in some rifles if i use a lee factory crimp die my accuracy is as good when i jump the bullets as it is when i load close to the lands.My rem 700 in 270 win has a long throat but i load to proper length because some of my buddies also shoot 270 and if i load long to fit my chamber it will not function in there rifles or feed in most mags.Reliability Is the most important part of reloading hunting ammo

Here is the reason, as I understand it. I am no bulletsmith, just some guy who has been doing this awhile. Better accuracy comes from a constant, predictable pressure build curve within the cartridge. This is achieved by seating the bullet just off the lands so that when pressure starts to build and the bullet starts to jump a little, the lands stop it and hold it there allowing the pressure to build until it is high enough to overcome that friction. This allows for more consistent round let-off and less bullet jump (which affects accuracy).
Since factory ammo cannot be built so that it is just off the lands of everyone's rifle, since every rifle is different, they have to do something similar to control that pressure curve and consistently provide similar pressures shot after shot. To accomplish that, they crimp the cartridge neck around the bullet, usually in the cannelure.
We can now do the same with the Lee Factory Crimp Die. It allows us to produce consistent ammo in our firearms when we are using different bullets or bullets that won't fit in our magazines, etc. I use it all the time since I am constantly playing with bullet weights.
Load a 110gr V-Max into your .30-06 at .050" off the lands and see how much bullet is still in the neck. Or load it to MOAL and crimp it. Better ammo that way.

 

[blargon]

Load them so they will cycle through your magazine. Don't worry about distance to the lands. If they don't shoot, seat them deeper, but not below the minimum OAL.

 

[jonas111]

Too Long

Here is the reason, as I understand it. I am no bulletsmith, just some guy who has been doing this awhile. Better accuracy comes from a constant, predictable pressure build curve within the cartridge. This is achieved by seating the bullet just off the lands so that when pressure starts to build and the bullet starts to jump a little, the lands stop it and hold it there allowing the pressure to build until it is high enough to overcome that friction. This allows for more consistent round let-off and less bullet jump (which affects accuracy).
Since factory ammo cannot be built so that it is just off the lands of everyone's rifle, since every rifle is different, they have to do something similar to control that pressure curve and consistently provide similar pressures shot after shot. To accomplish that, they crimp the cartridge neck around the bullet, usually in the cannelure.
We can now do the same with the Lee Factory Crimp Die. It allows us to produce consistent ammo in our firearms when we are using different bullets or bullets that won't fit in our magazines, etc. I use it all the time since I am constantly playing with bullet weights.
Load a 110gr V-Max into your .30-06 at .050" off the lands and see how much bullet is still in the neck. Or load it to MOAL and crimp it. Better ammo that way.

That is great information and exactly what I was looking for.

With the bullet seating tool the bullet COAL would be 3.352". The bullet would then not fit into the magazine. I adjusted them to 3.270" and they fit and chamber fine with a little room.

I went to the range yesterday with these bullets and they are shooting 2" groups at 200yds. I might try the crimping die to improve on this in the future.

Thanks again.