Seating depth question for 6.5x55

[mtang45]

I just started loading for a Cooper M22 in 6.5x55 and discovered that to load a Sierra 120 gr MK and set it up to be .010" off the lands that the bullet would only be seated about .06". Is this deep enough? And why so deep a throat? Are Cooper barrels freebored?

[Jamie6.5]

I've always lived by the rule that the minimum seating depth should be no less than 2/3rds of caliber.
(.264/3)*2=.176
I have the same problem with Sierra's 135gr MK in my .270. I can only get to ~.040 off the lands.
YMMV, good luck.

[mtang45]

Originally Posted by Jamie6.5

I've always lived by the rule that the minimum seating depth should be no less than 2/3rds of caliber.
(.264/3)*2=.176
I have the same problem with Sierra's 135gr MK in my .270. I can only get to ~.040 off the lands.
YMMV, good luck.

Jamie6.5 thats an excellent standard that I think I will adopt. I just didn't feel comfortable with the bullet barely seated in the brass. I assume your measurement does not include the boattail section of the bullet, and is just straight wall that actually has contact with the case neck.

I sure didn't know that Cooper freebored their barrels (like Weatherby) and it makes me wonder just how important bullet distance from the lands really is.

[swift]

Originally Posted by mtang45

I just started loading for a Cooper M22 in 6.5x55 and discovered that to load a Sierra 120 gr MK and set it up to be .010" off the lands that the bullet would only be seated about .06". Is this deep enough? And why so deep a throat? Are Cooper barrels freebored?

As this is a Scandinavian cartridge,this was originally loaded with long round nose 140+ Gr bullets,this bullets requires a long(6mm+ common) freebore area.This cartridge is in use by the Norwegian ''NRA'' shooters and is mostly loaded with long low drag bullets,and this bullets also require a long freebore otherwise it'll occupy to much of the case capacity(COL of 79-80mm is common)

[RT2506]

The 6.5X55 Swedes are throated so you can load the looooooog 160 gr RN bullets. I have 4 of the Swede military Mauser rifles , one sported with a scope that I hunt with some, and they all have the long throat. I have found that loading 120 to 140 gr bullets to an OAL of 3.050 which is as long as will work through my magazines well works great. One other thing that I have used in other rifles that have long throats that has greatly imporved the accuracy is to use a Lee Factory Crimp Die on the loads. This die makes it's own crimp groove so you can use it on any bullet. The principle behind it is to hold the bullet for that mill-a-second in the case just like the bullet hitting the lands will do in rounds loaded just off the lands so the pressure builds up good before the bullet leaves the case. I don't know if this is the reason or not but I do know that when I use this type crimp on long throat cambered rifles it shoots more accurate than loads not crimped. The only caliber that I could not tell the difference in is my Swedes. They both shot the same which is pretty good.

46 grs Accurate Arms 4350 with a 120 Nosler ballistic tip or 45 grs Accurate Arms 4350 with a Sierra or Hornady 140 gr bullet really shoots and scoots in my Swedes.

[mtang45]

Thanks for all the great replies! I picked this rifle up used and have seen pictures of one ragged hole groups that it has made, so I know its capable of some superb accuracy. Now I just need to get over my preconceived thinking on the bullet jump before the ogive hits the lands.

[Armed in Utah]

2.980" OAL using a 140 Sierra GK in my Tikka 6.5x55..........likes the jump !