Bullet into lands= velocity deviation?

[RangerBrad]

Loading bergers into lands(not intintional, just working up load) Can this cause large velocity diffrences? Bullets all loaded the same with H4831 can show as much as 30 to 60fps diffrence depending on grains of powder used with the heavier powder loads providing the larger diffrences. Could the bullet being jamed into the lands cause this? Thank's, Brad

 

[liltank]

Not necessarily. I would think it would have more to do with powder volume and primer. Not to mention if you are using virgin brass. I know that with virgin brass I get higher ES's than if I have just neck sized brass already formed to my chamber. Your seating depth will also adjust your ES. But the trade off is finding good accuracy.

Tank

 

[RangerBrad]

I am using all Winchester brass fired from my rifle, am very particular about measured amount of powder and Remmington 9 1/2 primers. Not doing anything special just resize, trim, deburr, clean primer hole, reprime, measure and add powder and seat 115gr Berger bullet. I am extremely new to reloading but, can't figure out what I must be doing wrong. Measurments are from a Competition Electronics Prochrono Chronograph. Have gone to the range several diffrent days and used several diffrent loads but always with the same problem. Any ideas? Thank's, Brad

 

[WildRose]

Loading bergers into lands(not intintional, just working up load) Can this cause large velocity diffrences? Bullets all loaded the same with H4831 can show as much as 30 to 60fps diffrence depending on grains of powder used with the heavier powder loads providing the larger diffrences. Could the bullet being jamed into the lands cause this? Thank's, Brad

Yep. Jamming it into the lans increases chamber pressure because less gas escapes around and then ahead of the bullet the bullet during ignition.

 

[backwoods83]

Seating bullets in the lands doesn't hurt a thing, I bet your not sorting the bergers by ogive length and your not using a comperator to check the seating depth, if you have one .010" in the lands, another .015" in and another .007" in then yes it will effect ES and SD. Try your combo with 115 noslers by jumping them and see if it brings the spread down if so that's probably your issue, bergers can be easy and they can be a pain in the ***!

 

[WildRose]

Loading bergers into lands(not intintional, just working up load) Can this cause large velocity diffrences? Bullets all loaded the same with H4831 can show as much as 30 to 60fps diffrence depending on grains of powder used with the heavier powder loads providing the larger diffrences. Could the bullet being jamed into the lands cause this? Thank's, Brad

Are you getting the greater variation with the heavier charge?

If so try backing off a bit.

Are you seeing any pressure signs on your brass?

 

[Topshot]

Depends on powder.
With Retumbo (AR2225) I get great results by jaming the 300gn Berger 0.015" into the lands to reduce ES and long range vertical.
Jaming assists uniform ignition with this slow powder.

 

[RangerBrad]

I am using H4831, I am seeing the greater descrepancies in the heavier charge of 54gr ( which is the recommended max for this caliber and bullet)and it is not shoing any pressure signs on the brass I am not using a compenator and cannot get true oal right now due to a faulty hornady gage. We pushed it back to fit in the magazine with a oal(not measured from the ogive at 3.341 which is well into the lands but not sticking 5the bolt to bad. Brad

 

[WildRose]

I am using H4831, I am seeing the greater descrepancies in the heavier charge of 54gr ( which is the recommended max for this caliber and bullet)and it is not shoing any pressure signs on the brass I am not using a compenator and cannot get true oal right now due to a faulty hornady gage. We pushed it back to fit in the magazine with a oal(not measured from the ogive at 3.341 which is well into the lands but not sticking 5the bolt to bad. Brad

I would say try backing off 1/4 or 1/2 grain at a time. That should solve your ES issue (not that it's terrible now) and tighten up your groups.

Normally as you reach max loads the ES opens up and so do the groups; at least that's what I've seen over the years.