Sierra 142 SMK Load Data (Coming from Berger 140s)

[upsdownsideways]

Going from 140 Berger Hybrids to 142 SMKs.

Any advice on how much to start off at? Bergers I am getting ES of 6, SD of 3 and a mean of 2725 @ 42 GR with Lapua LRP and Fed 210M primers.

 

[BigOldPhatboy]

What cartridge?

 

[Baddog 0302]

What cartridge?

AND what powder ??

 

[FatBoy]

Honestly, it won’t matter. IMO they are basically interchangeable unless you are so far out on the ragged edge your already dangerous. I have swapped between them in 6.5x47L and 6.5x284 for years with no load change. Jump then .015” - .030” and they shoot. Bergers had a little less MV but are flatter to 1k than even the pointed match king. My scores are the same, as is x count.

YMMV, but I pretty much swapped to the SMKs exclusive when they started pointing them.

 

[straightshooter1]

Honestly, it won’t matter. IMO they are basically interchangeable unless you are so far out on the ragged edge your already dangerous. I have swapped between them in 6.5x47L and 6.5x284 for years with no load change. Jump then .015” - .030” and they shoot. Bergers had a little less MV but are flatter to 1k than even the pointed match king. My scores are the same, as is x count.

YMMV, but I pretty much swapped to the SMKs exclusive when they started pointing them.

You say .015-.030: jump is what shoots well for you, but I don't know how that relates to the dimensions of my chamber. So, what's the COAL does that jump represent?

 

[FatBoy]

You haven’t said what you’re shooting yet, but assuming you’re not stuffing the bullet deep into the case, why would it matter?

Edit: looking at the OPs MV I assume 6.5 Creed.

some background. I have burned out 13 6.5x284s over the last 15 or so years. Three different chambers across the early ones and a 142SMK jumped between .015” and .030” has always shot if in the nodes. (2950-3000fps). I currently have 2x 6.5x47, same chamber but one I shoot Varget and the other h4350. Both jump a 142SMK .015” and both shoot sub half MOA rested. 2750-2830 fps.

I have use these same loads with the Berger 140 hybrid, but I jump the 140s .030” and they shoot the same size group as the 142s, though the DOPE is slightly off.

Maybe your expectation of accuracy is much stricter than mine? I wouldn’t be concerned at all to swap from 140s to 142 unless you’re running something like RL26 at a ludicrous velocity. Then, all bets are off.

As always, drop a few grains and work up but I think you’ll be pleasantly surprised.

 

[John Glidewell]

Sierra load data for 6.5 creed and 142 smk. Not hard to find. But you have yet to say what cartridge you are loading for.

 

[upsdownsideways]

For whatever reason I never got notifications to my email of replies. My bad.

Anyway,

Lapua LRP
H4350

 

[John Glidewell]

For whatever reason I never got notifications to my email of replies. My bad.

Anyway,

Lapua LRP
H4350

Creedmoor - PRC - x47 lapua?????

Please clue us in on the actual cartridge....6.5 WHAT!

 

[upsdownsideways]

6.5 creedmoor.

 

[Drbobinmo]

Just hold out for the Bergers. You don’t want the SMK’s .

 

[zeroz]

His jump and COAL doesn't represent anything for your gun. Hopefully you're measuring your current jump based on BTO measurements you have taken for your chamber. Measure the BTO of your current load and start there if you want to keep the same jump. SMK's are typically pretty jump friendly.

 

[upsdownsideways]

Ok, hit the range.. and lets say... I wasn't that impressed and a bit, well, confused.

I hit the range with the 142s and found this;

Shot	41	41.3	41.6	41.9
1	2737	ERROR	2796	2836
2	2734	2696	2786	2861
3	2724	2747	ERROR	2773
MEAN	2732	2722	2791	2823
ES	13	51	10	88
SD	6.81	36.06	7.07	45

The errors were my fault. I haven't used a Magneto chronograph in about a year and I forgot I had to keep adjusting the device or it continues to slide after a few rounds due to the recoil.

After my first shot at 41, I got a sticky bolt. Having gotten up to 2700s with the Bergers I was perplexed. I ejected the round, then every round afterwards never had a sticky reaction after that.

I might have to start lower than 41 and work my way up, what do you think? In comparison, this is what I was getting with the 140 Bergers;

41.2	41.5	41.5	41.8	42	42.5
2596	2618	2691	2695	2728	2769
2589	2618	2686	2699	2724	2772
2608	2619	2687	2671	2722	2776
2598	2618	2688	2688	2725	2772
19	1	5	28	6	7
9.61	0.58	2.65	15	3.06	3.51

I am very meticulous with my rounds. I use a single stage press with an electronic scale and forrestor dies and take my time from the first round to the last.

Suffice to say, I was a bit over the place with the SMKs.

Just so everyone sees what I am working with;

6.5 Creedmoor
Lapua LRP
H4350
Federal 210M

First graph is 142 SMK, second is 140 Berger Hybrids. (Which I am trying to get away from and transition to SMK)

 

[straightshooter1]

His jump and COAL doesn't represent anything for your gun. Hopefully you're measuring your current jump based on BTO measurements you have taken for your chamber. Measure the BTO of your current load and start there if you want to keep the same jump. SMK's are typically pretty jump friendly.

Agree with all that's said. . . good advice.

However, the emphasis on "jump" tends to distract reloaders where it's really not so important as seating depth. If I change bullets and use a current load, I want to start that new bullet with a seating depth that's the same as before regardless of the bullets BTO or bearing surface length (as long as it fits without touching or jamming the lands). I guess it's just become a pet peeve of mine that so many new reloaders are led to focus more on jump than actual seating depth, when seating depth is so much more important than jump.

 

[rmfield]

Agree. Once you get a bit away from the lands, jump doesn't affect pressure much, but increased seating depth reduces case volume and that can have significant affect on pressure and velocity. Its difficult to test jump and velocity nodes at the same time, but ultimately you have to get both right.