.224 95gr SMKs Old vs New

[InkedIan]

I received a new batch of 95 grain smks this week and out of curiosity I compared to some of the older ones I have and there is a definite difference. Only compared 5 of each but that was enough.

Old: Base to ogive measurement average is .0716
OAL average is 1.303
New: Base to ogive measurement average is .694
OAL average is 1.2782

The old ones are visually darker(may be from oxidation) and seem to be pointed further down the the jacket. I have no accurate way to measure it but with calipers it seemed the pointed area seems to be around .025" longer on the older ones.

There is enough of a difference to change a lot of different factors but I won't know for sure until I shoot them. According to the Berger twist rate stabilization calculator the shorter length adds .08 to their SG measurement in a 7 twist going 3000 fps. On the flip side will there be a b.c. drop? Anyone else notice this change?

 

[Ned Ludd]

I'm still working on my original Lot. However, what you're describing seems like normal, Lot-to-Lot variance to me.

An average OAL difference between Lots of over .020" is getting up there, but not the largest I've ever had. The difference between the two BTO values is obviously much smaller. Although technically the longer bullet should have the higher BC, we're likely talking about the third decimal place - so small a difference as to be meaningless. I'd imagine you might observe a slight difference in velocity; the new Lot will effectively give you just a tick more usable case volume. But I'm guessing a tenth grain or two at most, the difference isn't that large.

 

[InkedIan]

I have seen measurement changes from lot to lot but not this large across 3 different areas of the bullet. Only other bullet I've seen this much change in is the 115gr DTAC RBT but that was a design change. Just seems significant for a lot to lot variance.

 

[garandman]

What gun is this for?

 

[InkedIan]

What gun is this for?

Suppressed 20" 22 Creed is the plan. I'm probably going to try to keep them around 3050ish if they shoot good there.

 

[garandman]

Suppressed 20" 22 Creed is the plan. I'm probably going to try to keep them around 3050ish if they shoot good there.

I looked at 22 creed but got scared off when someone told me it's a barrel burner. I don't know if that's true or not. Your target velocity should help limit that .

 

[InkedIan]

I looked at 22 creed but got scared off when someone told me it's a barrel burner. I don't know if that's true or not. Your target velocity should help limit that .

I'd be happy with 1100-1200 and ok with 1000 competition rounds before replacing. I'm looking to something ballistically similar to my 6 Creed but shorter and less recoil for use with a suppressor. The 22 creeds overall length and weight should be the same as my 26" 6 Creed with a Fat bastard brake because the suppressor I'm using with 22 creed is heavy and long.

 

[garandman]

... because the suppressor I'm using with 22 creed is heavy and long.

Sounds like a plan.

I use an Ops Inc 12th over barrel mounted can for my 6.5 CM and will use it on my 224 V.

Are you shooting PRS where balance over a barricade matters, or is this for benchrest ?

 

[garandman]

Anyway... the differences you measured seem significant to me, especially for seating depth and distance to lands.

 

[InkedIan]

Sounds like a plan.

I use an Ops Inc 12th over barrel mounted can for my 6.5 CM and will use it on my 224 V.

Are you shooting PRS where balance over a barricade matters, or is this for benchrest ?

PRS style one day matches and hunting from a tripod once in a blue moon. I definitely prefer/want it to be front heavy.

 

[XTR]

As to color, there is something to the jacket or the wash that is done to them from Sierra that turns Sierra bullets the color of old pennies with time.

 

[InkedIan]

So here was a .013" difference from base of cartridge to ogive when touching the lands. The new ones seem to shoot pretty decent. I haven't done a load development yet but I loaded this up yesterday to get a general idea. I had a bit of pressure though. It seems slow but it is a 20" barrel

 

[Ned Ludd]

So here was a .013" difference from base of cartridge to ogive when touching the lands. The new ones seem to shoot pretty decent. I haven't done a load development yet but I loaded this up yesterday to get a general idea. I had a bit of pressure though. It seems slow but it is a 20" barrel
View attachment 1122235 View attachment 1122236

Ian - when you mentioned that bullets in the new Lot might be as much as .025" longer than the previous one, I was a little concerned for you. After looking at your preliminary and non-optimized results above, I think everything will be "OK" .