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Topic: SMK 150 Grain 6.5 CM (Read 434 times) previous topic - next topic

SMK 150 Grain 6.5 CM

Has anyone been reloading with the new SMK 150's? I was out the other day with my first attempts with them, and had decent SD's and velocities starting at 42 grains of superformance with .5 grain increments up to 44 Grains which got me to 2790FPS with an SD of 11. I plan on going up to 45 grains, but my groups were awful at 100. It could have been me, the wind, and the fact that my battery on my magneto was about to die. I was rushing.
Thoughts/Help will be well received.
Thanks.

Re: SMK 150 Grain 6.5 CM

Reply #1 –
IMO you are trying to push it too hard in the Creedmoor case.  Try to find a load that will get you in the 2690-2720 fps range with them seated at 0.010" off of just touching the lands.  I've only shot the 150 SMK's in a case with about 9-10gr more capacity than the Creedmoor case and although I could get stellar groups up to 300yds, at 600 and 1000yds I was getting some 'out of group' shots that cost me in competition.  However, I need definite .5MOA precision over 20+ shots for my needs and I strive for .3MOA over 5-8 shots in testing loads at 300yds.  The 150 SMK's could not consistently give me that. 

Re: SMK 150 Grain 6.5 CM

Reply #2 –
Exbonesny......What's your twist rate ??  I would guess the
pill is not fully stabilized at 100, at those speeds, and with
an 8 twist barrel.

I'm gearing up to work with this bullet. As a matter of fact,
Fedex is due today to deliver my 500 lot. I'll try to post a pic
of the length differences between the 140 RDF's, 142 SMKs
and the 150 SMKs.....Sierra does say for the Creedmoor load
data, you need a 7.5 twist or faster. I have a 29" , 7.5 twist
barrel coming from Brux. As Rardoin mentioned about capacity,
my plan is to load out long, in a single shot action, and start
the work with R-23.....Right now, I'm just a squirrel gathering
nuts. May not see any real data till April.
Keeping my bad Kharma intact since 1952

Re: SMK 150 Grain 6.5 CM

Reply #3 –
I tried from 44.3 to 47 Superformance on those pills, in my SAV 10 24" 8:1,  and got 2670 to 2860 fps.
Best groups were at 44.3, but it seemed to be on the ragged edge of stability and those groups were unacceptable (+1.5 MOA).
Stopped working with the 150 SMK cause apparently my  8:1 twist is not fast enough. 
... rule #9 ...

Re: SMK 150 Grain 6.5 CM

Reply #4 –
That bullet is fully stabilized, with his info.
2790 fps, 8 twist, (60 degs temp.) (500 feet elv.)
used low #'s just a guess   =1.59
You need 1.5 to be fully stabilized. A change to 2690fps
only changes it to 1.57
Twist is the biggest factor in stabilization, not speed.
You can have a difference of 100 fps and only change the
#'s by tenth's.
With the new sleek design (elongated ogive) you need
to really be careful of seating depth and concentricity
of those bullets. Just because it's the highest B.C. bulletin the
.264 class, doesn't mean you rifle will shoot it well.
You could try the Hornady 147 ELD-M it's at .697 very close
and might be easier to find the sweet spot, if the Sierra doesn't
work out.

Re: SMK 150 Grain 6.5 CM

Reply #5 –
The hardest thing to calculate is the point at which the bullet
goes to sleep. Maybe just a few yards past the muzzle, or out
beyond a hundred or so. Some groups suck at 100, but at 200 and
beyond, they find there life. And why most of my personal work
is at 300.

Fedex made it to my door just a bit ago. Here's the 150 SMK (1.480")
against the 142 SMK (1.377")   The 140 RDF falls right in between
them in length.
Keeping my bad Kharma intact since 1952

Re: SMK 150 Grain 6.5 CM

Reply #6 –
This is my setup. 1:7.5 twist 26" Hawk Hill Bighorn TL3, and specifically throated for these longer bullets. They are seated at .020 off the lands. I am going to possibly seat them out a bit...maybe to .010 but at .020 I had no pressure signs on the highest 44 gr superformance that got me to 2790

Re: SMK 150 Grain 6.5 CM

Reply #7 –
My barrel was an 8tw running at low 2900fps to mid 2900's.  I would say fully stabilized at that velocity but even so sometimes a bullet will perform better at a faster twist rate even though 'stable' at a slower rate,  I have not tried them in my 7.5tw barrel and, since I am having a .284 built to serve the purpose I was testing the 150's for I may not end up trying.  Your 7.5 twist is definitely spinning them fast enough for long range stability.  In both of the barrels I shot them in (8 and 8.5tw) they shot best at 0.008-0.010" off light touch and groups opened up further off out to 0.030"...where I stopped testing seating depth as I wanted to keep the bearing surface completely in the neck.  Now, when I mentioned them not grouping to my satisfaction that means consistent 5" of vertical with maybe some getting to 6" max over 20 shots in calm conditions (or at least not head/tail winds) at 1000yds and under 4" at 600yds.  I wish they fit my bill because I would not be building a .284 if they did ;) .

Re: SMK 150 Grain 6.5 CM

Reply #8 –
I would start at your .020 off and work towards .005
Hopefully you find a sweet spot. They seem to not like a lot of jump.
That's a really nice setup you have. 

Re: SMK 150 Grain 6.5 CM

Reply #9 –
fuj mentioned the 150 with re 23 the other day in a thread... so I did a semi ladder test with them and re 23 in my stealth... seated them out long and using half gr jumps got them in the 2850 range before I seen any pressure signs and even then they were minimal... in that little test it looked like they was a wide flat spot around 2850 with them … I didn't pursue it any farther... just wanted to see how they acted with that powder... when I get a new pipe for the stealth I may see what they can really do with re23... I think it will do great... so xbonesny you might give them a good shake down with re23 in your stick... I feel it would do well for ya...
Grant

Re: SMK 150 Grain 6.5 CM

Reply #10 –
This is all making my cabin fever worse....LOL

Alright, after a huge stack of French toast this morning,
I'm going to start sorting bullets. The points on this 500
lot of 150's is excellent. Overall lengths are all over the map.
I'll sort OAL first to establish lots, then do the base to ogive
measurement......I posted an overall of 1.480" for the first
bullet I pulled from the package.  A further look last night,
I found one at 1.486", and one at 1.477".  That was just from
sampling 20 pills. During that sampling, I did not run across
another 1.480".....Maybe dig out a few of the"Rush" albums
for the process !!
Keeping my bad Kharma intact since 1952

Re: SMK 150 Grain 6.5 CM

Reply #11 –
Did a chamber check in my Criterion to see where this 150 SMK
will hit the rifling. First off;  My port on the Savage precision
action that will let a loaded case eject cleanly is, 3.040". Doing
5 passes, I'm getting, 2.962"  I have a good .220" in the case neck.
So if I test a few in FrankenCreed, I have some jump room before
getting too far into the boiler room. I hope Mike still has my
chamber cast and not melted down for something else. I'd like
to replicate the chamber into the incoming Brux barrel.

I am having a problem with checking base to ogive. The taper is
so sharp, it's jambing in the tool with even a light touch. I started
to notice this with the RDF's but the 150's are worse. I'll  be turning
up a new gage just for this pill, and see what shakes.
Keeping my bad Kharma intact since 1952

Re: SMK 150 Grain 6.5 CM

Reply #12 –
You might copy the Sinclair .260 insert with the tapered wall.
 

Re: SMK 150 Grain 6.5 CM

Reply #13 –
Quote from: jvw2008 on
You might copy the Sinclair .260 insert with the tapered wall.

Found a quick and dirty work around. The Lee floating nose,
seater plug, I honed to fit the RDF's, works. Just need to drill
the nose deeper to clear the tip.
Keeping my bad Kharma intact since 1952

Re: SMK 150 Grain 6.5 CM

Reply #14 –
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