Sierra Heavy TMK 6MM Testing

[philcox]

Does it come up to the base of the shoulder? IIRC (probably don’t), that’s where it usually is for me

Yep, looks about there.

 

[schmidty3]

You guys suck (yet again). 6mm dies, 18" 1-7" Pbb .750 fluted barrel, and 116s when they drop are (or will be) ordered.

 

[Hurley88]

Yep, looks about there.

Yeah, then it’s not low enough case fill to be concerned about IMO. I’ve never had issue with angled shooting or erratic velocities or anything. But then again I don’t seat the bullet up the case neck, I want the whole neck grabbing the bullet.

I say rock on, I’ve gone through at least three jugs of H4350 in 243/6CM in the 41-41.5 range.

 

[nphunter]

Pretty pleased with the 107’s. Went and checked my ballistics and my drop chart is right on using sierras BC with my actual velocity.

Shot a 3”ish seven shot group at 500 and then backed up to 730 and shot three shots right at 2” holding 3/4 mil for wind, last two were 3/4” apart.

Final load:
41.5gr H4350
Peterson Brass
CCI BR2
Coal 2.918”
.022 off lands
2760fps

1:8, Tikka 16” barrel

 

[ID_Matt]

Pretty pleased with the 107’s. Went and checked my ballistics and my drop chart is right on using sierras BC with my actual velocity.

Shot a 3”ish seven shot group at 500 and then backed up to 730 and shot three shots right at 2” holding 3/4 mil for wind, last two were 3/4” apart.

Final load:
41.5gr H4350
Peterson Brass
CCI BR2
Coal 2.918”
.022 off lands
2760fps

1:8, Tikka 16” barrel

View attachment 1036600

View attachment 1036661

At 2.918” those gotta be barely in the case don’t they? I have some loaded for tomorrow. 2.785” was right about where the boat tail hits the neck/shoulder junction.

 

[nphunter]

At 2.918” those gotta be barely in the case don’t they? I have some loaded for tomorrow. 2.785” was right about where the boat tail hits the neck/shoulder junction.

I’m using M+ (6.5cm mags) they wouldn’t fit in the factory .243 M mag, the 108ELDM was right at mag length and it’s a shorter bullet.

 

[5MilesBack]

At 2.918” those gotta be barely in the case don’t they? I have some loaded for tomorrow. 2.785” was right about where the boat tail hits the neck/shoulder junction.

This one is loaded to 2.880" for a Tikka 243. You can see that the boat tail starts really close to that junction. At 2.918" his are just over 1/32" further out.....not much.

 

[ID_Matt]

I’m using M+ (6.5cm mags) they wouldn’t fit in the factory .243 M mag, the 108ELDM was right at mag length and it’s a shorter bullet.

Ahhh. I thought this was 6 creed. Ignore me!

 

[ID_Matt]

Not sure if this belongs in the other TMK thread or this one, but i got to shoot the 107’s today.

Tikka action
18” benchmark barrel spun by soldier mountain arms
Tbac Magnus suppressor
Xlr chassis

Hopefully the notes in the picture make sense. Ran a ladder with H4350 and N560 to see if I’d hit pressure and to check velocity. Never loaded 560 in this case before so wanted to try it. Decent speed but accuracy was not near as good as H4350 so i won’t pursue it any more.

It’s obvious these bullets want to shoot. Even jumping 150 thou in my chamber. 0.7” for the 7 shot ladder across 3 grains of powder and then a 3 shot group with 1 charge that was sub 0.3”. Never hit obvious pressure but i imagine it was close at 42.0.

Saved 10 at 40.5 to shoot at distance. Plate was 600 yards and wind was gusting 15-30 MPH so ignore the horizontal. About 4” of vertical roughly. BC from Sierra website just below water line.

 

[ztc92]

Similar to others, I found the new 107 TMK to shoot well with multiple loads/powders. Way better results compared to the 95TMK with the same powders. I still haven’t found a great load for the 95TMK yet…

I’m going to hold off on sharing charge weights as I had a few blown primers (which was a big surprise and a new issue for me). For the record, all of these powder charges were below book max if there was book data available. If there wasn’t book data, then I used slightly lower charges than others have reported with comparable bullets (107 SMK, 108 ELDM). I’ll be loading some more up with lower charges and then hope to work my way back up.

All 107’s were loaded to 2.860” in an M+ mag as I couldn’t chamber them at 2.880”. I do wonder if I should load shorter next time, as I’m thinking a lack of jump on a few rounds that ended up slightly longer than planned could have been the reason for the occasional blown primers that happened with multiple powders at safe charge weights.

Tikka 243, cut to 16.5”
Once fired norma brass
CCI 200 LR primers

Powders tried:
H4350
H1000
IMR4831
WIN760

 

[Fireflyfishing]

All 107’s were loaded to 2.860” in an M+ mag as I couldn’t chamber them at 2.880”. I do wonder if I should load shorter next time, as I’m thinking a lack of jump on a few rounds that ended up slightly longer than planned could have been the reason for the occasional blown primers that happened with multiple powders at safe charge weights.

So you don’t know the COAL measurement where the bullet touches the lands? I would start by finding that measurement and/or the ogive measurement with a comparator…and then start load development.

 

[ztc92]

So you don’t know the COAL measurement where the bullet touches the lands? I would start by finding that measurement and/or the ogive measurement with a comparator…and then start load development.

Thank you, I thought I had that figured out by making some dummy rounds and doing some test fitting yesterday before actually loading ammo but that’s one variable I need to sure up.

I plan to do a more precise measurement today as you’ve suggested and then work my way up in charges once I know the bullet is nowhere near the lands to rule that out. I’ll report back when I know more.

Edit: I should add I thought I was safe since others are loading this to a bit longer in their own tikka 243’s but perhaps my chamber/throat is a bit shorter. That’s what I get for being in a hurry to go try the new bullets…

 

[Fireflyfishing]

I plan to do a more precise measurement today as you’ve suggested and then work my way up in charges once I know the bullet is nowhere near the lands to rule that out. I’ll report back when I know more.

Edit: I should add I thought I was safe since others are loading this to a bit longer in their own tikka 243’s but perhaps my chamber/throat is a bit shorter. That’s what I get for being in a hurry to go try the new bullets…

Cool, I hope that helps.

Like any reloading recipe, I always ensure the case measurements are taken on my particular rifles…as they’re all different, right? The only time I’m more lax on finding lands measurements is on my auto loaders when I know I’m loading to mag length. But, I still use headspace and bullet comparators to setup my dies for those auto loading cartridges.

There are a number of ways to find the lands measurements for your rifle. I think the easiest is using the Hornady OAL gauge and modified case.

Good luck!

 

[ztc92]

Cool, I hope that helps.

Like any reloading recipe, I always ensure the case measurements are taken on my particular rifles…as they’re all different, right? The only time I’m more lax on finding lands measurements is on my auto loaders when I know I’m loading to mag length. But, I still use headspace and bullet comparators to setup my dies for those auto loading cartridges.

There are a number of ways to find the lands measurements for your rifle. I think the easiest is using the Hornady OAL gauge and modified case.

Good luck!

As an update for you and anyone else with a factory Tikka 243…

I used the very technical “cleaning rod and masking tape” method to find that with a bullet touching the lands, my COAL was about 2.845” using the 107 TMK.

When shooting yesterday I was loading them to 2.850” so I likely had a spike in pressure with a few rounds that ended up a smidge longer and were actually into the lands.

I’ll be trying to load up again with a COAL of about 2.820 with an estimated jump of about 0.025” and see how they shoot with a ladder of H4350 since that seems to be the easy button and has given good speed for others.

I’ll report back when I get to try again, hopefully next week sometime.

 

[huntsd]

As an update for you and anyone else with a factory Tikka 243…

I used the very technical “cleaning rod and masking tape” method to find that with a bullet touching the lands, my COAL was about 2.845” using the 107 TMK.

When shooting yesterday I was loading them to 2.850” so I likely had a spike in pressure with a few rounds that ended up a smidge longer and were actually into the lands.

I’ll be trying to load up again with a COAL of about 2.820 with an estimated jump of about 0.025” and see how they shoot with a ladder of H4350 since that seems to be the easy button and has given good speed for others.

I’ll report back when I get to try again, hopefully next week sometime.

Doesn’t mag length, m or m+, limit you from getting near the lands?

 

[Libtard McSocalist]

Looking forward to seeing how the 107s treat at a 2 day this weekend. 6GT 2940 MV.

 

[ztc92]

Doesn’t mag length, m or m+, limit you from getting near the lands?

I was using M+ mags so no issue there, they allow up to about 2.975 for COAL.

The standard M mag seems to allow about 2.840 based on my rough measurement but that would be touching both ends and likely wouldn’t function very well.

I assume most who are using a 243 with the 107’s will end up with M+ mags, otherwise you’d have to load around 2.80” and give up some potential velocity to do so.

 

[mtnbound]

Did some more testing with the 107 TMKs. I will have to redo 4831SC as I forgot to turn on my chronograph. My old barrel liked H4350 but this one doesn’t seem to like it as much.