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77GR TMK's for Varminting?


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Considering a custom barrel in 1:8 twist for longer range varminting.

 

I think the only bullet that would be suitable would be the 77gr TMK. The appeal, for me, is the high BC. Problem is, they aren't technically a varmint bullet. I'm led to believe they do break up well on impact, but how frangible are they?

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Considering a custom barrel in 1:8 twist for longer range varminting.

I think the only bullet that would be suitable would be the 77gr TMK. The appeal, for me, is the high BC. Problem is, they aren't technically a varmint bullet. I'm led to believe they do break up well on impact, but how frangible are they?

Very. Check out my YouTube vid using them to cull rabbits. Just type in '77gr TMK vermin'.

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That's great news. I ordered some last week. Postie should be here today along with new Lapua brass brass.

I have a 1-8 twist 26in medium profile barrel in .223 Wylde. I did purchase them mainly for longer range target shooting but after watch the YouTube video longer range pest control is definitely on the cards.

What sort of velocity are you getting from your rifle? Cracking video and some really good footage.

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From the start grains to the max there is 17 possibilities for load development going up in .2 gr.

20.8 start - 24.2 max

If done in 5 shot groups it soon mounts up. Then once found the accuracy node there Bullets seating. So it could hit 70 rounds before the load is developed.

Do you guys shoot 5 shots in the group?

Is 3 the way to go?

Start in the middle?

Start below min?

Which way do you start?

One YouTube video shows load developing in 10 shots. (6.5 guys)

Albeit it's fun load developing but would rather be shooting a developed load.

Anyone trying or tried this 10 shot load development?

 

I have N140 powder just to add to the post.

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I've been using the 69's for longer range vermin control for a year or more and they've been reliable, accurate and effective. Wouldn't use anything else. For load dev, I have found them very barrel fussy though and as well as load, I've had to play with seating depth. Far harder to tune a load in my rifle with them than with smks.

 

I like to start somewhere like 10 thou off the lands, about half-way down the recommended load range and work up in .3 intervals until I start getting pressure signs (or work up to max recommended), then back off by about a grain or slightly less to allow for some powder sensitivity depending on conditions, to work out development range to start with. I then load in 0.3 intervals between those limits and shoot groups of 3, marking each and noting their relative positions to POA, and select those loads which group in a similar vertical spread, rejecting the few that group either side of that. I then load 5 of each remaining load and shoot carefully aimed groups of each load, selecting the three tightest, and repeat at least 3 times until I find the one which seems the tightest.

 

Once I have this, I vary seating depth by 30 thou back out to 130 thou, or until I get to a compressed load. I've always then found at least one or two nodes at one or two different seating depths where the groups appreciably tighten and you soon see very clearly with these bullets IME an opening up of the groups as you come off the node. I guess that you could just stick to one seating depth and vary the load but I found that just didn't work for my barrel and the 69 TMKs.

 

Yet to try the 77's but I mean to.

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Very. Check out my YouTube vid using them to cull rabbits. Just type in '77gr TMK vermin'.

 

Si

 

what propellant are you using in the .223 with those? I have been using N140 but switching to SR RS50 to see if I can get a little better velocity. (my 69s shoot at about 2800).

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Good help there.

It's the seating depth that has my concern due to longer bullet. So the 2.260 that my 55gr sit at won't work with the 77gr without compressing the load.

So maybe working back off the Lands is the way to go. Although I was criticised to a fashion in the past by pissing around trying to find the lands at the start of the development.

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It always pays to find where the lands are as you need to ensure with longer bullets, especially if single fed, to check that you aren't jamming the rounds which can raise pressures. It's easy enough to do without any special tools, just using an old case with a split cut into the neck. TMKs can be very finicky to jump compared with smks, hence it got me thinking about barrel time. Sometimes, you just can't tune a load properly without playing with seating, and with TMKs in my barrel, I found that the 69s at any rate needed about 10 thou or 100 thou. In between, the groups opened up considerably so that by 60 thou out, they were all over the place, tightening up again by 100 thou which seemed to produce the best results at quarter moa.

 

You can vary the charge to allow you to play with seating and chances are you'll find a node that way even if the group isn't there at close to lands. My loads are lightly compressed at 100 thou as the seating is at 2.6 OAL with the 69 bullet (I use 23.6gr N140). In your case, you can load back out towards the lands once you've checked but you may then find that you have to single feed as much beyond 2.6 OAL you'll be past magazine length.

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Elloit, what about the new 75 Amax or the 80 grain Amax, the new ELD range. Check out the BC's on them bad boys. They expand at rabbits etc even at 800 yards, i know this.

 

What are your thoughts?

 

Steve

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