maximum seating depth for 257WBY MAG

[jdl420]

So the bad news is some mild throat erosion the good news is I don't have to retire it quite yet, the gunsmith suggested seating the bullet out as far as the magazine will allow. In the past my oal was 3.285 for my 120gn speers and was the same for the 110gn accubonds. The most I can get out of the Mark V magazine is 3.400 so I have set these rounds at 3.395". Anyone else ever have OAL approaching 3.395

 

[GB300wm]

I do the same with my Mk V. I have my 115 bergers at 3.36" because that's where it shoots really well with H1000. :grin: :grin:

 

[Kodiak]

Nope, most of my .257 loads are @ 3.250". My powders are H-1000 and RL-22 with the 110 AB and the 100 gr. BT. I've probaly got about 300 shots down the stainless barrel .

How many rounds have you got down the barrel at this time?

Best of luck seatin' 'em out :lol: .

Jim

 

[jdl420]

Somewhere between 900 and a 1000 rounds over the last 30years

 

[Powerstroke]

Most of my guns I use as a single shot most of the time anyway. My .257 Bee I have seated well beyond magazine max length.

What twist barrel do you have? I surprised to hear you're able to shoot the heavier bullets, as most of the older .257's didn't have a fast enough twist to stabalize them..........

 

[jdl420]

My 257 is a japanize made mark v and has a 1-10'' twist

 

[jdl420]

My mistake it's a 1-9''twist

 

[hardpan]

I am using 3.349. But, 900 to 1000 rounds is a lot of rounds for a Bee!
Hardpan

 

[jdl420]

So when you are looking for the right seating depth how many thousandths do you vary between groups i.e. I've started with 3.395'' then went to 3.390'' then 3.385 etc etc... or would it be better to go by 1-3 thousandths?????

 

[hardpan]

I go by 5 thousandths... no engineering reason.