77gr Sierra Tipped MKs

[freedom]

Anyone have any load data specific to the polymer tipped match kings? The B.C. is .420 at velocities greater than 2400fps. The regular MK BC is only .360 in comparison. I'm having trouble finding data that's not the normal bullet.

All I have powder-wise right now is Varget and benchmark.

 

[qodeBebop]

I just started with the same charge you would for the SMK when I tried the 175 .30cals

 

[DarthVader]

There's a good thread on M4Carbine.net about the new tipped SMK.

 

[freedom]

I was planning on starting on the low end of the regular SMKs and working up, but the bullet length is a bit longer, definately longer than the 75grs I have.

I saw a thread on arfcom and the sniper forums, but nothing other than a few individual recipes.

There was some worry about overpressure when seating to magazine feeding depth.

@qodeBebop when working up a load, how many grains do you increase at a time? The loading for this is between 22 and 24. I normally just go up a 1/2 at a time, but that was for plinking loads. I'm still learning and have never done more than rudimentary load development.

 

[DarthVader]

http://www.m4carbine.net/showthread.php?t=163635

 

[freedom]

http://www.m4carbine.net/showthread.php?t=163635

Thanks. That's better than other threads I was finding. I might have to join M4carbine

 

[DarthVader]

Keep an eye on Markm's posts. He's a solid resource for reloading info.

 

[qodeBebop]

For .308 sized cases I do .3 and .223 i do .2.

Look up Dan Newberry's OCW method. Basically load three at each charge weight and shoot them round robin at their own target and look for the nodes where different charge weights have the same point of impact.

I'm not the most expierenced reloader but I've had good success. Last time I switched bullets for my .308 my load development was 20 rounds at 100 yards and won a competion the following week with distances out to 1000 yards. It works. I also do all of my load development over a chronograph. You may pull a shot and ruin the group but if the velocity numbers are tight you'll know it has potential.

 

[freedom]

For .308 sized cases I do .3 and .223 i do .2.

Look up Dan Newberry's OCW method. Basically load three at each charge weight and shoot them round robin at their own target and look for the nodes where different charge weights have the same point of impact.

I'm not the most expierenced reloader but I've had good success. Last time I switched bullets for my .308 my load development was 20 rounds at 100 yards and won a competion the following week with distances out to 1000 yards. It works. I also do all of my load development over a chronograph. You may pull a shot and ruin the group but if the velocity numbers are tight you'll know it has potential.

Hopefully I can hook up with someone with a chrono when I go to the range. Looks like I'm going to need to get one eventually.

 

[freedom]

@handloader and any other more experienced guys...

I just loaded up 50 test loads, starting at 23grs and increasing .2 to 24.8 grs. The manual on 77gr smks goes between 22.5 and 25.

There is a slight ring deformity on every bullet now, just under the polymer tip. From my understanding the tip of the bullet is basically hollow to balance the bullet towards the rear middle to increase the B.C..

It's this a problem? Sorry for the potato phone pic.

 

[qodeBebop]

Hard to tell from the pic but is it an actual indention like you can catch it with a finger nail or just enough there to be visible? How hard were the bullets to seat?

 

[freedom]

Hard to tell from the pic but is it an actual indention like you can catch it with a finger nail or just enough there to be visible? How hard were the bullets to seat?

On the lighter loads, it's a faint impression. On the 24.8, probably a compressed load, you can see the indentation. The line of bullets on the left is the heaviest loading.

They all felt about the same when pulling the handle down.

 

[qodeBebop]

Could be the bullet profile not jiving with the seating stem in the die and the compressed loads would obviously amplify the effects due to the increased effort to seat the bullet. I remember the 175 tmks seated to the same length to the ogive as my SMKs gave me a really long COAL. Faint marks aren't anything to worry about tho.

 

[becausefu]

Could be the bullet profile not jiving with the seating stem in the die and the compressed loads would obviously amplify the effects due to the increased effort to seat the bullet. I remember the 175 tmks seated to the same length to the ogive as my SMKs gave me a really long COAL. Faint marks aren't anything to worry about tho.

I bet this mother fucker knows what he's talking about with a seating stem

 

[EugenFJR]

On the lighter loads, it's a faint impression. On the 24.8, probably a compressed load, you can see the indentation. The line of bullets on the left is the heaviest loading.

They all felt about the same when pulling the handle down.

I dont reload, but if you want, I have some 77 grain Black hills ammo from the AMU, if you want to try them out, and I know a person who has the load data for the AMU black hills ammo, if they work for you... Just LMK, if you want some.

 

[freedom]

I should be shooting tomorrow, I guess if the compressed load turns out to be the most accurate, then it doesn't matter. We will see.

 

[DarthVader]

I dont reload, but if you want, I have some 77 grain Black hills ammo from the AMU, if you want to try them out, and I know a person who has the load data for the AMU black hills ammo, if they work for you... Just LMK, if you want some.

Is the AMU load equivalent to Mk262?

I should be shooting tomorrow, I guess if the compressed load turns out to be the most accurate, then it doesn't matter. We will see.

In for results.

 

[freedom]

This is my first semi-scientific approach to reloading. I've made a few before, but I was more doing it to teach myself.

The load is 77gr Sierra TMK, CCI 400 small rifle primers, and Varget powder. The OAL is as long as I could make it and have it load in a magazine, 2.27".
My test batch went from 23grs of Varget to 24.8. I stepped up .2 at a time based on the method @qodeBebop mentioned earlier. I was hoping to meet up with a friend with a chronograph, but he couldn't make it.

Comparison between a 55gr fmjbt, and the 77gr TMK


Not to make excuses, but I can't find my bipod. Instead of prone with the bipod, I shot with a bag off a bench. I shot at 100 yards, and removed the iron sights to mount a scope for testing. I used 8x throughout. I shot a group of PMC bronze as a control, the group was bigger than what I've gotten before. I measured the groups with calipers and either measured outside edge to inside edge, if they were spread out, or outside to outside and subtracted .22.

 

[freedom]

Didn't look like a good way to start.

Pmc bronze control- 1.63
23gr- .94, in the middle
23.2- 1.15
23.4- 1.67
23.6- 1.47

I was not very impressed at this point. I feel like I was a bit off, based on the test group, but I was hoping for better.

 

[freedom]

The next target is much better.





One may be a flyer or my fault, I wish I knew.