240smk's in 1:10 barrel

[abinok]

240smk\'s in 1:10 barrel

I posted a few weeks back in the buy/sell section looking for some 240smk's for my 300WM. I got them a couple of days ago (THANKS LEN!!!) and shot my ladder test yesterday. Even brought the girlfriend along to distract me between shots. I had wondered if these would stabalize... and stabalize they did. My highest node was a 4 shot cluster measuring 1.020 @300 yds. Not too shabby for a hunting rifle Imo. I don't have access to a chrony full time, so ill wait to get the velocity until after ive picked the load. Book says about 2650.The paint is drying on my 8x8 portable target stand... should be interesting to see how many of those smk's find their make at 1400 on thursday. Once again thanks len for the help, and for this wonderful site!!

 

[Brent]

Re: 240smk\'s in 1:10 barrel

2650 from a 300 wm. What length bbl?

The 240 will go subsonic at 1150 yards with a MV of 2650.

In case anyone may wonder, they will not stabilize in a 11 twist at 2900-3000 fps. That was with 85-90 gr Retumbo in the 30.5" bbl 30-338 Lapua Imp.

From memory they printed around a 14" group at 400 yards, and all went through the cardboard sideways.

 

[Guest]

Re: 240smk\'s in 1:10 barrel

abinok
I'll be looking forward to your report about how they did at 1400. I have a 300 RUM w/ 1-10" twist and was hoping they would do good out to 1500yds. I've shot them at an estimated 2800fps at 300yds and for two three shots groups averaged 1.1875" and one at 600yds for a 3.8" group, slightly windy and I rushed the shots as it was getting late. Barrel has 28rds thru it and when time permits will up the charge to try and reach 2900fps.
Thanks in advance for the info,
Wayne

 

[abinok]

Re: 240smk\'s in 1:10 barrel

2650 from a 300 wm. What length bbl?

Im using a 26" barrel. Like I said im basing that velocity on book data since I don't have a crony full time. Im looking at the sierra manual and they list data to 2700 wih h4871sc. I use this same powder for my "fit in the mag load" for my 220smk's the book says 2700 for the load im using. I get 2733. Ive gone faster with h1000, but the h4831 just seems to shoot better if im seating bullets deep.

The 240 will go subsonic at 1150 yards with a MV of 2650.

Running the .711 bc (ive seen that #listed commonly and its what sierra uses for their first velocity level) at 2650 on the sierra infinity program with my locl conditions (im at 1330ft asl) It says subsonic at 1580. Ive also got the horus vision program, and the old "ballistix for windows" and they all agree on that distance within 15yds. Were you using sea level?

From memory they printed around a 14" group at 400 yards, and all went through the cardboard sideways.
Ive only shot these at 300, but they all cut clean holes. I did notice that they have quite a bit more flight noise than the 220's ive been using. Kinda makes me think of artillery /ubbthreads/images/graemlins/grin.gif

 

[Rob01]

Re: 240smk\'s in 1:10 barrel

I've shot the 240s in my 1 in 10" twist also and got excellent results. Nice clean holes and good groups. Velocity was at about 2650fps also but I think that could be bumped up a little as I wasn't using a near max load. With a RUM I think you could add a couple of hundred FPS.

 

[abinok]

Re: 240smk\'s in 1:10 barrel

Thanks for posting rod
I figured id post since I hadn't seen anybody posting about this twist bullet combo. I can only assume that the twist that sierra lists is geared toward those shooting in lower elevations and temps.
It just snowed here, so itill probably be mon or tues before more bullets fly.

 

[Rob01]

Re: 240smk\'s in 1:10 barrel

Just some more info that I forgot and got reminded of in your post, I'm shooting mine at sea level as I live on the coast and the temps were in the 50-60s when I was shootng them.

 

[Brent]

Re: 240smk\'s in 1:10 barrel

Not sure what I had entered but the BC or MV I entered must have been off, looks like 1500 yards would be fine looking at it again.

 

[abinok]

Re: 240smk\'s in 1:10 barrel

Howdy everybody.
Finially had a day here with winds below 35mph(steady at 7, gusting to 15), so early in the am I hurdled some 240's at my 400 yd target. Nothing fancy just load development. Taken on its own, this test was mildly successful. All the groups I shot went into less than .75 moa, but none under .5moa. Considering that this rifle will reguraly shoot between .75" and and inch with my 220 SMK load at this range, I wasn't too excited. Tomorrow morning im going to load some 220's to throw at my new portable target stand. I finished surveying over the weekend for points at 1000, 1200, and 1400. Provided the wind cooperates, in the next few days I should have my first holes in paper past 1000.

 

[abinok]

Re: 240smk\'s in 1:10 barrel...well kinda

Finially, got my computer fixed!!!
My portable target stand has been up "on the hill" for 3 weeks now. I haven't found a good load for the 240s yet, but I figured I might as well give it a try with the 220s. Driving out to shoot the first time at this range was a bit intimidating. ive been shooting various precision rifle sports for quite a while, but ill admit that for a minute there was a bit of aprehension as to whether or not this was even remotely possible. I know a lot of you guys have no problem shooting at this range, but with a good deal more equipment (read $) than I do.
Wind to my back at 10mph, and switching from 5 to 7 oclock I released my first shot. The first shot impacted low ( I shot with a 1200 yd correction... I need to recalibrate my mildots), but perfectly in line with the stand. 11.5 moa and 2 shots later I had a bullet hole within 1" of my poa.
I shot 2 3 shot groups with two loads:
220smk, 68.4gr of h4831sc 75fps of es
220smk, 73.0gr of h1000 15fps of es
the 4831 load is shorter and fits in the mag, the h1000 is a single shot load.
The 4831 load (and my first group) was 19.5", with a 21" following it.
The h1000 load was 15.5" and 31.5" The last shot in the last group was credited to the shifting winds at my back, but the first 2 landed just 6" apart!
There are several things that I could have done to shrink those groups, and ill try as soon as the snow melts.
Anybody else have any experence with groups at these ranges?