Warning

 

Close

Confirm Action

Are you sure you wish to do this?

Confirm Cancel
Member Login
Site Notices
10/20/2017 1:01:18 AM
9/22/2017 12:11:25 AM
Posted: 9/6/2005 5:28:24 PM EDT
I have a new upper with a 16" barrel and 1/8 twist designated for home defense. I am sold on Black Hills ammo for Self Defense but am not sure which round offers the best terminal performance, 75 or the 77 grain Sierra MatchKing.

Also I see Midway offers rounds with or without moly coating - what is the value of the moly coating?
Link Posted: 9/6/2005 6:57:31 PM EDT
75 yaws faster and therefore has the superior terminal ballistics even though the 77 has a greater % fragmentation IMO. 75 is also less expensive. Moly reduces friction which reduces velocity. This allows you to load to higher velocity with more powder with less pressure or get better velocity with the same pressure. Its not needed at all and I suggest skipping it to keep cost down unless you just gotta have a black bullet because it looks cool.
Link Posted: 9/6/2005 7:28:22 PM EDT

Originally Posted By DevL:
75 yaws faster and therefore has the superior terminal ballistics even though the 77 has a greater % fragmentation IMO. 75 is also less expensive. Moly reduces friction which reduces velocity. This allows you to load to higher velocity with more powder with less pressure or get better velocity with the same pressure. Its not needed at all and I suggest skipping it to keep cost down unless you just gotta have a black bullet because it looks cool.



I think DevL meant that "moly reduces friction, which INCREASES velocity."

Tack
Link Posted: 9/6/2005 8:15:27 PM EDT
Hi, long time reader, first post, exactly how long is the yaw length for the 77gr smk?
Link Posted: 9/6/2005 10:21:25 PM EDT
why don't you go with a "hunting " bullet?

One that will expand and plow through.

Link Posted: 9/7/2005 4:16:19 AM EDT

Originally Posted By Tack:

Originally Posted By DevL:
75 yaws faster and therefore has the superior terminal ballistics even though the 77 has a greater % fragmentation IMO. 75 is also less expensive. Moly reduces friction which reduces velocity. This allows you to load to higher velocity with more powder with less pressure or get better velocity with the same pressure. Its not needed at all and I suggest skipping it to keep cost down unless you just gotta have a black bullet because it looks cool.



I think DevL meant that "moly reduces friction, which INCREASES velocity."

Tack



No I did not. It REDUCES velocity. Take two loads one with moly one without that are identical and the moly has lowered pressured and LOWER VELOCITY. Common sense is non-sense.
Link Posted: 9/7/2005 4:16:56 AM EDT

Originally Posted By Blammer:
why don't you go with a "hunting " bullet?

One that will expand and plow through.




Because he wants superior terminal ballistics to what you are describing.
Link Posted: 9/7/2005 4:29:49 AM EDT

Originally Posted By 223plinker:
Hi, long time reader, first post, exactly how long is the yaw length for the 77gr smk?



www.ammo-oracle.com, you'll find this information as well as plenty of other information in this thread which is tacked to the top of the Ammunition Forum.

BTW, IIRC your looking at about a 7" neck or so for the Sierra Matchkings, much less for the Nosler 77 grn. OTM.

Mike

ps - always review the "tacked" threads in the forums, as there is alot of excellent info most of these threads, highly beneficial to s..........
Link Posted: 9/7/2005 10:26:46 AM EDT
alright let me try rephrasing my question...with a 7" yaw on a 77gr smk, is it still viable for self defense? It would seem that the bullet would through most of the body before yawing on a head on shot, and does the addition of a cannelure on the mk262mod1 bullet change the yaw rate at all?
Link Posted: 9/7/2005 1:31:58 PM EDT
To my knowledge cannelures have zero effect on yaw.
Link Posted: 9/7/2005 7:12:48 PM EDT
Thanks DeVL and others for your responses. I will test a few hundred rounds of the 75 gn to make sure it functions then load up.
Link Posted: 9/8/2005 2:01:09 AM EDT
[Last Edit: 9/8/2005 2:05:24 AM EDT by mr_wilson]
Testing SHTF ammo in YOUR rifle is a good idea, as the main reason I use the BH (bluebox) 77grn. SMK as my SHTF ammo is two fold.

1. It is the same bullet now used in latest version of the MK262 by the military.

2. It shoots much tighter groups out to 400 yards through my 1/7 twist M4s than the Hornady 75grn. BTHP used by Black Hills.

Here's a typical 100 yard group (77grn. SMK) through my LMT 14.5" KAC RAS II, Aimpoint M2 optic equipped:



POA was center of large square as M2 dot covers 4" at 100 yards.

YMMV in your rifle.

Mike

ps - neck length/yaw depth is inconsequential to me as a CNS hit or head shot as mentioned will not change the fact that target is eliminated.
Link Posted: 9/8/2005 12:43:47 PM EDT

Originally Posted By DevL:
No I did not. It REDUCES velocity. Take two loads one with moly one without that are identical and the moly has lowered pressured and LOWER VELOCITY. Common sense is non-sense.


To expand on this, less friction means the pressure curve builds slower. The effect is similar to a severely eroded throat (ie, way too much freebore).
Link Posted: 9/8/2005 6:44:51 PM EDT
ok, another question, if one was to choose between the xm193 and the 77gr smk round for self defense within, one's house, which one would be preferable? The smk fragments more and more consistently, but the xm193 has a much shorter yaw length. Each one seems to have its pros and cons.
Link Posted: 9/8/2005 6:55:29 PM EDT
Why not just use the 75gr Hornady bullet, as loaded in Hornady TAP 75 or Black Hills 75gr?
Link Posted: 9/9/2005 6:53:43 AM EDT
tag
Link Posted: 9/9/2005 7:34:10 AM EDT
Does the Black Hills load have a cannelure?
Link Posted: 9/9/2005 8:29:45 AM EDT
For 75 grain? Yes both Blue and Red box. For 77? Used to not have one. Have not seen one recently though.
Link Posted: 9/9/2005 3:11:39 PM EDT

Originally Posted By Zak-Smith:
Why not just use the 75gr Hornady bullet, as loaded in Hornady TAP 75 or Black Hills 75gr?



You can't go wrong with either. For a self-defense application the 75gr in a 1:7 or 1:8 it is hard to beat. All my 5.56MM RECCE's shoot the Hornaday 75gr TAP more acuratley and consistently than most 77gr SMK loadings, the only exception to date has been the MK262 Mod1, which is close enough.
Top Top