140 smk vs 142 smk

blackbeard

blackbeard

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I searched this forum and could not find the info i would like.

I found a smokin load for my 6.5x55 with 140 smk, but i ran out of them.
I have 142 smk left. Where can I find the bullet dimensions for each? I know the 142 are longer and have the measurement for them and the 140. I dont have the tools to measure the bullets proper.Is the ogive measurement the same between the two, meaning if i dont change my seating die(140gr coal) and seat a 142gr, will my jump be the same? Hope my question makes sense.
 
My Tikka T-3 in 6.5x55, loves the 142. Due to the long boattail, I can't seat them anywhere close to the lands, but it does' seem to matter.
 
i cant seat close to lands either, the bullet falls out! Mine is chambered in the t3 sporter. 3/4" at 200 yds with 140 smk. really impressed considering that was fireforming new brass as well.
 
Your dies seater stem should be using place on the bullet that measures .263 or so, so jump should be the same. Now, if your bullet seater is making contact at the nose of the bullet, all bets are off! Hope my answer makes sense.
 
that is more or less the answer i was looking for. the overall difference in bullet length is about the same as the overall difference in COAL.I will try a bunch in the spring and see how they shoot.Now just waiting for my muzzle brake to come in!
 
I believe the nose profiles are a bit different between the two but am not 100% about that at this time - I'll let you know if I can find where I read that. Otherwise, why don't you give Sierra's tech line a call? One other thing since your throat is so long, load some up at Sierra's recommended OAL and have at 'er! Sounds like the 140's weren't that picky, maybe the 142's will act the same.

Rooster
 
i left my die at the 140 measurement i use and loaded up a dummy 142 and smoked the bullet, closed the action and no markings in the smoke.the nose profile is slightly different (visually). Was more curious if the start of the bearing surface was the same distance from the base on both bullets. If these dont work you mite get them back rooster!!
 
I just verified the COL that I am using for the 142 at 3.10". We are using the same COL for these bullets in my T-3 Varmint, a friends T-3 Super Varmint, and another friends T-3 Sporter. All three rifles are shooting sub 1/2" with the 142 ahead of R-22.
 
I seat at 3.10" for the 140gr and the seating die i did not adjust and seated the 142 gr at 3.14". .04" is the approx. difference in bullet length.Thanks for the info guys. If it does not like that length, I will shorten the 142 gr down to 3.10
 
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