300gn SMK past transonic barrier.

[wadcutter]

Anyone shot the .338 Cal 300 grain SMK bullet through the transonic zone and into sub-sonic velocities?

I shot out to 2285 yards today with mixed results and I would be interested to hear what others have found at extreme range with this bullet.

 

[ARMECA]

Re: 300gn SMK past transonic barrier.

I've shoot them to 1900 yards, but have had some vertical dispersion at this range.
In fact, vertical dispersion begin at 1400 yards with differents loads.

 

[Armorman]

Re: 300gn SMK past transonic barrier.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: ARMECA</div><div class="ubbcode-body">I've shoot them to 1900 yards, but have had some vertical dispersion at this range.
In fact, vertical dispersion begin at 1400 yards with differents loads. </div></div>

Did you run your load through exbal or some other ballistics program? I'm just wondering what your velocity would be at 1400 and 1900 yards?

Thanks,
Chris

 

[rmfield]

Re: 300gn SMK past transonic barrier.

In the summer months at the NRA Whittington Center, I noticed that mine stay supersonic past 2000 yards. DA makes a big difference at these ranges.

 

[wadcutter]

Re: 300gn SMK past transonic barrier.

My load was going sub sonic at about 1750 yards. So had to travel another 500 odd yards.
Two out of three landed close to each other but the others dropped way short. Some by about 10 to 15 yards.

The line of travel seemed to be real good. but some just gave up and hit the dirt low.

 

[wadcutter]

Re: 300gn SMK past transonic barrier.

Went out again this morning and shot at the 2285 yard target, this time with a 2900fps load.
Same result.
1 out of 3 bullets hit the dirt way low.
Back to the drawing board............

 

[wadcutter]

Re: 300gn SMK past transonic barrier.

Well it was back out into the field this morning and this time I tried the 250 grain Hornady BTHP Match bullet at the 2285 yard range.
Well this bullet shoots quite well out to this distance, although I only hit the target once, the impact points in the dirt made a group much much smaller than the 300 grain SMK and there were no bullets that hit the dirt way low.
So from this shoot I would say that this bullet is the one to use if shooting to extreme range past the transonic barrier.

 

[Armorman]

Re: 300gn SMK past transonic barrier.

That sounds great. What is your muzzle velocity with the 250's and the barrel twist?

 

[wadcutter]

Re: 300gn SMK past transonic barrier.

I loaded 99 grains of H1000 and chronographed a couple at 3087 and 3144 fps. My chronograph is not that reliable so I was not too worried about the spread. I used a nominal 3100 fps to work out my initial drop.
The barrel twist is a standard 1 : 10 lilja barrel.

 

[Armorman]

Re: 300gn SMK past transonic barrier.

Are you shooting this out of a 338 Improved version or a standard 338 Lapua chambering?

Chris.

 

[wadcutter]

Re: 300gn SMK past transonic barrier.

Armorman, it is a .338 Edge not a Lapua.
A hot tip when shooting at extreme range is to adjust more for elevation than what appears to be needed fron spotting the bullets hit the ground.
This is due to the steep angle that the bullet is comming down at when it hits the ground.
If POI appears 2 MOA low then it is most likely hitting the ground 10 yards in front of the target. The true point where the bullet would pass directly under the target might be 5 MOA low. I made this mistake, but will not the next time I shoot this distance.

 

[GOING FOR 2000]

Re: 300gn SMK past transonic barrier.

Try lehigh solids higher BC.

 

[Longshotrifles]

Re: 300gn SMK past transonic barrier.

Smokin99 and I have shot a ton of them at 2100 yards with very good results. Haven't played with them much over that as that's where the gong is set up. If temps are in the 40's and air is 26"hg or more they are running about 1070fps and still shoot well. If air drops a few points in pressure to say 25.5" it puts me a hair over 1100 fps and I honestly don't see an improvement.
I'm planning on shooting some data when it warms up a little for the 350 SMK. I've shot it to 2400 yards with very good results but need to add a couple hundred yards to go transonic from there.

 

[wadcutter]

Re: 300gn SMK past transonic barrier.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Trgrman</div><div class="ubbcode-body">Smokin99 and I have shot a ton of them at 2100 yards with very good results. Haven't played with them much over that as that's where the gong is set up. If temps are in the 40's and air is 26"hg or more they are running about 1070fps and still shoot well. If air drops a few points in pressure to say 25.5" it puts me a hair over 1100 fps and I honestly don't see an improvement.
I'm planning on shooting some data when it warms up a little for the 350 SMK. I've shot it to 2400 yards with very good results but need to add a couple hundred yards to go transonic from there. </div></div>
Trgman,
What calibre and what are your rifle specs to be shooting a 350 SMK that is still supersonic past 2400 yards? A 375 chey-tac?

 

[Longshotrifles]

Re: 300gn SMK past transonic barrier.

Yes it is a 375 CT.
What are you at for air pressure to go subsonic a mile? Must be close to sea level.
On the 300 SMK's I shoot the 338 RUM and Smokin was shooting his 338 EDGE with both rifles running the same velocity at 2805 fps.

 

[wadcutter]

Re: 300gn SMK past transonic barrier.

Yes I am close to sea level. Only 200m elevation. About 992mb pressure for the shot.

The .338 Edge is a great cartridge.

My velocity was 2815 fps for the 300 SMK on my first attempt then bumped it up to a hot 2900 fps to see if this helped, it didn't.
Was very impressed with the way the Hornady pills survived transition.

 

[jp67]

Re: 300gn SMK past transonic barrier.

Wadcutter
what barrel life do you expect shooting your 338 Edge?
Thanks

 

[wadcutter]

Re: 300gn SMK past transonic barrier.

About the same as a .338 Lapua I would say.

 

[jp67]

Re: 300gn SMK past transonic barrier.

I heard it is around 3000/4000 rouds? Does that sound correct?

 

[wadcutter]

Re: 300gn SMK past transonic barrier.

I will be happy with 1500