Bullet length. 168 SMK vs 175 SMK

[little_scrapper]

Can someone tell me the difference in length between 175 and 168 SMK base to tip. I dont have any 168's and was wondering how long they are.

Yes I know tips are not all equal. Give me a rough difference. ie .030"

Thank you

 

[straightshooter1]

Can someone tell me the difference in length between 175 and 168 SMK base to tip. I dont have any 168's and was wondering how long they are.

Yes I know tips are not all equal. Give me a rough difference. ie .030"

Thank you

~ .051

 

[little_scrapper]

Wow more than I thought. I have 168 tipped match kings and they are actually longer than the 175 gr SMK's.

So the point to my question. I am trying to figure out how/where that difference effects the seating depth and over-all-length.

I assumed the extra length would be more in the body portion that engages the lands vs the tip. Therefore, I assumed there would be very little OAL difference as I figured the ogive to tip would be similar on both rounds.

 

[918v]

It depends on the lot. 168’s I’ve played with we’re about 1.200”, while 175’s were 1.225-1.255”.

 

[straightshooter1]

Wow more than I thought. I have 168 tipped match kings and they are actually longer than the 175 gr SMK's.

The tipped SMK's are a whole different ballistic design to where they have a higher BC. But if you compare a 175 SMK with with a tipped 175 SMK, you'll find that the distance to the ogive for both is pretty close to the same . . . though the length is quite a bit longer for the tip configuration.

So the point to my question. I am trying to figure out how/where that difference effects the seating depth and over-all-length.

The overall length really has little to do with seating depth. It's the base to ogive that is key. More precisely, it's actually the distance from base to where the seating pin makes contact with the bullet, which is somewhere a little above the ogive and just exactly where depend on who's seating die pin you're using.

I assumed the extra length would be more in the body portion that engages the lands vs the tip. Therefore, I assumed there would be very little OAL difference as I figured the ogive to tip would be similar on both rounds.

The difference from ogive to tip is probably where one sees the most difference depending on the particular ballistic design. You'll also see differences in bearing surface length. When you add of the differences in the various segments of the bullet, that where you see the difference in OAL.

Note that there's about .030 difference between the 175 SMK and the 168SMK, but I figure you already know that since you mentioned that number as an example.

 

[little_scrapper]

Note that there's about .030 difference between the 175 SMK and the 168SMK, but I figure you already know that since you mentioned that number as an example.

I have a couple charge weights that seemed promising. For example 41.6 gr of Hodgdon 4895 shot just under 1MOA with the 175 SMKs. So now I intend to run a small ladder from 41.4 to 41.8 to not only prove 41.6 wasnt just a fluke but also see if a bit higher or lower is better. Also, I plan to run several of these series varying the "jump" in say .005" increments.

However, right now max mag length is already giving me a .020" jump. I need to double check my numbers though.

 

[straightshooter1]

I have a couple charge weights that seemed promising. For example 41.6 gr of Hodgdon 4895 shot just under 1MOA with the 175 SMKs. So now I intend to run a small ladder from 41.4 to 41.8 to not only prove 41.6 wasnt just a fluke but also see if a bit higher or lower is better. Also, I plan to run several of these series varying the "jump" in say .005" increments.

However, right now max mag length is already giving me a .020" jump. I need to double check my numbers though.

.020 jumps works pretty much as well as .010 does for me with H-4895 with the 175 SMK's. For my gun, 41.0 grs (a mild load) worked very well for me for my shorter range shooting. And 42.5 grs worked well for my 168 SMK's.