Terminal performance: 69tmk vs 77tmk?

[SDHNTR]

I've killed deer with both, and have noticed little difference honestly. I suppose I'd prefer a 77 all things considered, but I certainly wouldn't re-barrel an accurate .22 chambering if it shot the 69s well.

Dave

This was my original point, better said here.

 

[dieselchessy]

Interesting theory that I’ve never heard before. Have you seen this tested or discussed somewhere? I’d like to look into this more

Here is a link to a video with similar(?) size bullets and a more extreme RPM difference that demonstrates little to no difference. Small sample size of course.
May well be a non factor.

 

[sierracharlie338]

Need to watch that when I’m not at work and my attention isn’t divided but at first glance, too many apples to oranges for a scientific explanation IMO. But I’ll watch it again for reference and see what kind of reading I can find on the topic.

 

[Pharmseller]

The only real difference is 69gr TMK penetrates about 20-30% less than the 77gr TMK.

I’d pay attention to this guy.

Why not buy a new 1-8” or 1-7” rifle? Sounds like you have good reason.

As if you need a reason…




P

 

[sierracharlie338]

I’d pay attention to this guy.

Why not buy a new 1-8” or 1-7” rifle? Sounds like you have good reason.

As if you need a reason…




P

I consider his opinion higher than most here. Just mainly looking for terminal performance data at this point though I’m leaning heavily to what you alluded to.

 

[Forestryguy]

Go look in the firearms forum at the .223/5.56 thread that has all of this already answered.

 

[sierracharlie338]

Go look in the firearms forum at the .223/5.56 thread that has all of this already answered.

Lol nice effort.

 

[xsn10s]

Is there a legit difference in construction? Like a thicker jacket to the 77?

For example, there is a genuine construction difference in the 168gr .308 TTSX and the 180gr TTSX that is far more meaningful than 12 grains.

Petey308 did the cross section on my LRH thread. In short the jacket thickness was the same. https://www.longrangehunting.com/th...-69-gr-tmk-on-game.344704/page-3#post-2953653

 

[BAC]

Is there a substantial POA/POI difference within the mean point blank range between the 69 & 77gr TMK's?

 

[sierracharlie338]

Is there a substantial POA/POI difference within the mean point blank range between the 69 & 77gr TMK's?

I have not started testing either yet due to a slow twist rate for the 77s but when I go that route I will update but I’m sure some others may be able to say.

 

[TN deer hunter]

Whichever works/shoots best in your rifle. Deer won't know the difference...dead is dead!

 

[doty_soty]

You’ll be trading fragmentation for penetration by going heavy, or vice versa. The impact velocity matters here. You don’t want it going too fast or it’ll splat, and too slow (<1900ish) and it won’t frag well.

 

[Chris_in_Idaho]

You’ll be trading fragmentation for penetration by going heavy, or vice versa. The impact velocity matters here. You don’t want it going too fast or it’ll splat, and too slow (<1900ish) and it won’t frag well.

Assuming an impact velocity of at least 1800fps, wouldn't the heavier one both fragment better and penetrate better?

 

[Der Schwabe]

My personal experience is with the 69 TMK.
3250 fps muzzle velocity - 22-250
297 yards impact in neck
No exit. Both of us could hear the impact. Bullet remnant weighed 17 grains, base was intact.
Deer weighed 200+ lbs.

 

[Der Schwabe]

My rifle has a 1-10" twist and shoots the 69 TMK like crazy. Nevertheless, I will be stepping up to a 1-8" twist barrel and shooting the 77 TMK. The 69gr did not have the penetration I would like. I say re-barrel to a 1-8", or even 1-7" so you can also shoot the 88 ELD-M. It's only money!

 

[sierracharlie338]

Good info, thanks for sharing.

 

[Thegman]

Another thing to consider is that twist rate (rotational RPM) also plays a role in penetration.
Your losing weight of the projectile as well as RPM’s.

RPM is dependent on twist and muzzle velocity. The higher velocity of the 69gr may make that a moot point despite a slower twist barrel. Need both numbers to calculate RPMs.

 

[FCCDerek]

I've seen a lot of deer shot with various 223 bullets. Every one of them resulted in a dead deer. Is the 69TMK ideal? No, but if your rifle shoots them well and you place that bullet where it needs to go every time I wouldn't change anything until your barrel is shot out.

 

[Kimber7man]

My personal experience is with the 69 TMK.
3250 fps muzzle velocity - 22-250
297 yards impact in neck
No exit. Both of us could hear the impact. Bullet remnant weighed 17 grains, base was intact.
Deer weighed 200+ lbs.

View attachment 686186View attachment 686187

Great buck!