Sierra 150 grain 6.5 Matchking
- Thread starter MLC
- Start date
I don't know if an 8 will stabilize. However, in a 6.5 x 284 this bullet with either H1000, RL-26 or Retumbo should easily get to 3000.. Additionally, with those powders you should get 14-1500 rounds of barrel life! This ought to be a real 1000 yard F-Class champ>>>>>IF it shoots!!
According to my numbers at 3000fps. a 1-8.184 would be the min. twist required.
Don't forget about temperatures, elevation, humidity etc....all play a part.
If you have a true 8 twist barrel they should fly for ya.
I'm doing a faster twist for my 6.5 Creedmoor.
Later, Frank
Bartlein Barrels
Don't forget about temperatures, elevation, humidity etc....all play a part.
If you have a true 8 twist barrel they should fly for ya.
I'm doing a faster twist for my 6.5 Creedmoor.
Later, Frank
Bartlein Barrels
Long answer: I think FrankG is probably using the Miller SI rule at 60 F and standard pressure at sea level and assuming a 1.5" bullet, which I saw posted by "Fast14riot" in thread "New Sierra 6.5 mm 150 gr Match King" on the main forum board today. When I do that, I get Miller SI of 1.44 for 1:8 twist, so I think Frank is calculating minimum twist rate for a 1.4 corrected Miller SI. In recent work, Litz said some improved results can be achieved by stabilizing up to a 1.5 Miller SI. My calculations show a 1.53 corrected Miller SI from a 1:7.75 barrel.
After looking at other similarly-low form factor 6.5 mm bullet data especially 140 and 147 ELD Match bullets, I am skeptical that 1.5 is the right bullet OAL. I think the correct OAL for the SMK may be closer to 1.45" instead of 1.5". If the bullet is indeed something closer to 1.45", then Miller SI at 1:8 twist is 1.59, and it is 1.50 with a 1:8.25 twist.
Short answer: At 3000 fps, if bullet is 1.5" long you may want a 7.75 or faster twist. If bullet is 1.45" long, then 8.25 or faster will be good.
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Ran the 147gr ELD at 3220 this summer then backed it down to 3180 ish this fall in a 30" Kreiger 6.5X284. ( R26)
Should be no problem at all
Great to know. Thanks
Close....I use a old graph and math formula for calculating twist rates. It's always been pretty accurate for me and whatever number it gives me I consider it min. required and the number it gives me then I error on the faster side. A little faster twist will not hurt you.
The preproduction bullets I seen measured 1.455" in length. I haven't received any of the production bullets yet.
We made a few accuracy test barrels in different twist rates for Sierra also.
The bullets are very nice looking with a closed tip and for a box match bullet they (Sierra) is doing a very nice job!
Later, Frank
Fast14riot
Gold $$ Contributor
In the test I read, advertised length was 1.5, measured for the lot being tested was 1.498-1.5. Sierra techs confirmed 1.5 as advertised length, verified by another poster later in that same thread. I'll have to see if I can find that FB post again and link the site that did the testing.
Edit: Team Area 419 on Facebook did the testing in a 260.
Edit: Team Area 419 on Facebook did the testing in a 260.
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I’m curious to see which is best between the 6.5x55 or 6.5x284 to launch these bullets...
Or will the 6.5 creed or 260 be enough to get decent velocities?
Or will the 6.5 creed or 260 be enough to get decent velocities?
I load the 147 to 2825 with Re 26 in my .260 and it will safely do a bit more, so the 150 should do about the same I would think. Mine has a 24-inch barrel.
Redoing my numbers.....at a 1.5" long bullet in 6.5mm. At 2800fps. my twist calc. comes out at a 1-7.92 min. At 2600fps. I'm getting 1-7.52 min.
If it was my gun I'd run a 1-7.25 min. twist or a 1-7. I'm throwing a 1-6.75 twist on my gun in 6.5 Creedmoor here in the near futures. I'll see how it shoots!
Later, Frank
If it was my gun I'd run a 1-7.25 min. twist or a 1-7. I'm throwing a 1-6.75 twist on my gun in 6.5 Creedmoor here in the near futures. I'll see how it shoots!
Later, Frank
Sounds like if pushing it around 3000, an 8 twist will stabilize it just fine.
17VLD
Gold $$ Contributor
Nice b.c.of .713.Sierra is really changing the game,when my 6.5WSM needs a barrel(won't be long)I will make sure I get the correct twist for this
bullet.It is encroaching on 7mm country,my Leopard shoots the 142MK at 3300fps and is very flat shooting,can only imagine how nice this bullet should shoot.
Matt
bullet.It is encroaching on 7mm country,my Leopard shoots the 142MK at 3300fps and is very flat shooting,can only imagine how nice this bullet should shoot.
Matt
147g ELD-M, 150g SMK, 155g Cauterucio VLD.
Kentucky Reloader, could you measure lengths on a few of those 150 SMKs and give us the numbers? The 147 ELD is supposed to be 1.435 and the 155 Caut is supposed to be 1.460. Just from looking at the picture that would make the SMK maybe 1.465 or maybe 1.470 at the most. Could even be a little less because that 155 looks like it took a nose-beating. People have been saying 1.50 but that doesn't appear to be correct.
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