Sierra Heavy TMK 6MM Testing

[Q_Sertorius]

Winchester or White River primers? If White River, it has been suggested to try something else if you have grouping issues.

Winchester

 

[Bluumoon]

Winchester

I'm with you, I'd try a different powder.

 

[Q_Sertorius]

The book coal is just a starting spot for entry level reloaders, find lands then load between .040-.060” deeper than lands.

I don’t think we are on the same page. I’m not anywhere close to the lands as far as I can tell (sharpie method). I can’t load any longer or the ammunition won’t fit in the magazine.

 

[blacktailcentral]

I don’t think we are on the same page. I’m not anywhere close to the lands as far as I can tell (sharpie method). I can’t load any longer or the ammunition won’t fit in the magazine.

Then you need a different magazine if you can’t be in the ballpark of the lands then thats likely the problem. Some bullets like alot of jump but most do not from my experience

 

[Q_Sertorius]

I'm with you, I'd try a different powder.

I think so. The other possibility is the nut behind the rifle. The three best 10-shot groups I have shot with this rifle are all around 1.6” (two with 107s, one with factory 100-grain). While I have shot some nice groups in my time, I am probably the largest source of error.

 

[cq0302]

I think so. The other possibility is the nut behind the rifle. The three best 10-shot groups I have shot with this rifle are all around 1.6” (two with 107s, one with factory 100-grain). While I have shot some nice groups in my time, I am probably the largest source of error.

What is the rifle capable of with other bullets? Have you tried n560? Do your own pressure test, but 44.5-46gr n560 is what I would likely try next. If that doesn’t work, different bullet.


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[Q_Sertorius]

What is the rifle capable of with other bullets? Have you tried n560?


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The rifle has exactly 130 rounds down the tube. The (60) 100-grain factory loads did around 1.6-1.7” for 10-shot groups, but most were used to shoot the 8” steel at 300.

The 116s were truly deplorable (and not the good kind). This is the first two loads I tried. First one is marked with purple, second is unmarked.

I shot (50) of the 116s with H4350 and never got better than a 2” group.

I don’t have N560, but I will consider it if the H4831sc doesn’t work.

 

[Jordan Smith]

I’m using quality components
Lapua
It’s virgin so not annealed or trimmed
I would think since it’s Lapua neck thickness shouldn’t vary too much?
Gm 205 lrp

I’ll never shoot this gun past 700. you guys don’t think that es spread will show up at that distance?

Lapua is some of the best brass there is, but it’s not immune to the odd poor lot. I would measure neck thickness variation on that lot. I also agree with the others that said your consistency should improve on the second firing, as long as your brass processing method is consistent. I would also consider a hotter primer to ensure good ignition with ball powders (probably not the issue, but worth trying).

An ES of over 100 fps is enough to cause misses at distance.

For reference, I chrono’d two loads yesterday, a 20-round group with an ES of 45 fps and an SD of 13, and an 8-shot group with an ES of 37 and SD of 12. Both were with thrown powder charges, this first with Superformance and the second with H4350.

In general, I wouldn’t put too much faith in any statistical analysis your chrono provides of groups less than 10 shots, and 20 is much better, while 30 shots starts to inspire some statistical confidence.

 

[eoperator]

The rifle has exactly 130 rounds down the tube. The (60) 100-grain factory loads did around 1.6-1.7” for 10-shot groups, but most were used to shoot the 8” steel at 300.

The 116s were truly deplorable (and not the good kind). This is the first two loads I tried. First one is marked with purple, second is unmarked.

I shot (50) of the 116s with H4350 and never got better than a 2” group.

I don’t have N560, but I will consider it if the H4831sc doesn’t work.

Is this 12ga or 20ga? #4 buckshot?

 

[bonepoint]

The rifle has exactly 130 rounds down the tube. The (60) 100-grain factory loads did around 1.6-1.7” for 10-shot groups, but most were used to shoot the 8” steel at 300.

The 116s were truly deplorable (and not the good kind). This is the first two loads I tried. First one is marked with purple, second is unmarked.

I shot (50) of the 116s with H4350 and never got better than a 2” group.

I don’t have N560, but I will consider it if the H4831sc doesn’t work.

I thought I was the only one who didn't have good luck with H4350 (when loading the 103X and 109M). I got better velocity and better groups with RL16.

Currently trying RL16, H4831sc, 6.5 Staball, and N560 with the 116s. Had some loaded up to try this weekend, but it rained all weekend.

 

[bonepoint]

What is the rifle capable of with other bullets? Have you tried n560? Do your own pressure test, but 44.5-46gr n560 is what I would likely try next. If that doesn’t work, different bullet.


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I was actually just getting ready to load up some of the 116s with N560. I haven't seen it mentioned much, but seems like it would be a good fit for these heavies. Not a lot of data out there, but was going to start with 44g. Have you taken it up to 46 without pressure? How did it shoot for you?