Me too. Haven't heard a thing about them.
Okay, except this article:
http://bulletin.accurateshooter.com/...k-from-sierra/
A tipped and pointed meplat from the factory. Requires a "twist rate of 1:7.5″ or faster to stabilize.”
They show up in the New Products page at Sierra:
https://www.sierrabullets.com/products/new.cfm
Okay, except this article:
http://bulletin.accurateshooter.com/...k-from-sierra/
A tipped and pointed meplat from the factory. Requires a "twist rate of 1:7.5″ or faster to stabilize.”
They show up in the New Products page at Sierra:
https://www.sierrabullets.com/products/new.cfm
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Just saw the Instagram post on them, very interested in loading them in 6.5cm.
(Note: my velocities for the SMK are just conservative guestimations based on other factory loadings. I’d imagine they’ll be able to be pushed a bit faster than 2600, but I prefer to under estimate than over estimate.)
Playing around in Ballistic AE comparing it to the factory hornady 143gr ELD-X load @2700fps with the 150gr SMK at 2600 the new 150gr SMK still has .2mils less drop and .2 less mils of drift with a 10mph constant 90* wind at 1000. The SMK also has a predicted 150 yards further of supersonic range, but I’d prefer the g7 numbers before I trust anything past 1000.
overall it seems like a nice little bump compared to the heavy hornadys, assuming they’ll work at mag length and keep competitive velocities. I like the way an all metal bullet looks compared to the ballistic tip stuff too. My only concern is how they’ll handle transonic.
(Note: my velocities for the SMK are just conservative guestimations based on other factory loadings. I’d imagine they’ll be able to be pushed a bit faster than 2600, but I prefer to under estimate than over estimate.)
Playing around in Ballistic AE comparing it to the factory hornady 143gr ELD-X load @2700fps with the 150gr SMK at 2600 the new 150gr SMK still has .2mils less drop and .2 less mils of drift with a 10mph constant 90* wind at 1000. The SMK also has a predicted 150 yards further of supersonic range, but I’d prefer the g7 numbers before I trust anything past 1000.
overall it seems like a nice little bump compared to the heavy hornadys, assuming they’ll work at mag length and keep competitive velocities. I like the way an all metal bullet looks compared to the ballistic tip stuff too. My only concern is how they’ll handle transonic.
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Bender
Compare it to the 147 ELD-M. The 143 ELD-X has a much lower BC.
I run the 147 at 2820fps from my 27" Creedmoor so guessing the 150 will be close to that.
ETA: Just ran the average of the three velocity bands of the 147 ELD and the new 150 SMK and the 147 comes out at .665 and the 150 SMK at .673
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I've been shooting the 147 eld m exclusively and will be watching closely for the data to roll in for the 150 smk. Would like to shoot these in both 6.5cm and 6.5 SAUM. Both barrels are 8 twist so stability is my main concern. Team Area 419 had a post on their FB page with some pretty good info. 260 with 8.75 twist if I remember correctly.
I have some on the way should be testing by next week in my saum (8 twist).
I was disappointed with the 147 eld . After developing a good load and getting zeros for them,Hybrids and RDFs , I tested them from 500 all the way to a mile, at 1400 yards the Hybrids and RDFs were impacting with Exactly the same drop.
The 147s were about 2' low or roughly .5 mils low.
using their stated BC they should have been .75 High
I stuck with the Hybrids,maybe these SMKs will change my mind.
I was disappointed with the 147 eld . After developing a good load and getting zeros for them,Hybrids and RDFs , I tested them from 500 all the way to a mile, at 1400 yards the Hybrids and RDFs were impacting with Exactly the same drop.
The 147s were about 2' low or roughly .5 mils low.
using their stated BC they should have been .75 High
I stuck with the Hybrids,maybe these SMKs will change my mind.
I decided not to try the 147's in my 6.5Saum/8.5 twist because I think the "full BC" potential isn't there until a faster 7.25 twist is used. The rule will still apply to the Berger 155 and the Sierra 150 IMO. In other words those heavier bullets will be driven slower and the BC not maximized with the 8 twist.
What could be happening is there might be a 50-75 fps loss in velocity and the BC of the 147 is more like .65???
What could be happening is there might be a 50-75 fps loss in velocity and the BC of the 147 is more like .65???
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Rob,
I went to Hornady and used the 140gr/ .646BC vs the 147gr/.696BC in the 4 dof calculator with 2820fps and there was a .3 mil difference at 1020Y. .2 mil is a 7.2 inch group which isn't easy to lay down at 1000Y. I'm not doubting your dope was correct but there are other factors to consider that could cause more than a clicks difference, like which side the wind was blowing from - affecting the vertical, what temp it was that day/ammo temp(adjusting to 2800fps fps changed the calc .15 mils), and if your zero was perfect, heck even scope tracking could be off a tenth???
I tried googling the article that I read which was about twist rates affecting BC's and couldn't find it. I thought it was a Hornady article??? Maybe someone else knows where it is. I was trying to figure out what possibilities there could be for why Sean's 147's landed short. I did see that the 225 ELDM 30 cal has a .777 BC with a 10 twist and a .798 BC with a 7 twist.
I do fully admit I'm definitely no ballistic expert. The same factors I mentioned could have affected Sean's dope as well???
I went to Hornady and used the 140gr/ .646BC vs the 147gr/.696BC in the 4 dof calculator with 2820fps and there was a .3 mil difference at 1020Y. .2 mil is a 7.2 inch group which isn't easy to lay down at 1000Y. I'm not doubting your dope was correct but there are other factors to consider that could cause more than a clicks difference, like which side the wind was blowing from - affecting the vertical, what temp it was that day/ammo temp(adjusting to 2800fps fps changed the calc .15 mils), and if your zero was perfect, heck even scope tracking could be off a tenth???
I tried googling the article that I read which was about twist rates affecting BC's and couldn't find it. I thought it was a Hornady article??? Maybe someone else knows where it is. I was trying to figure out what possibilities there could be for why Sean's 147's landed short. I did see that the 225 ELDM 30 cal has a .777 BC with a 10 twist and a .798 BC with a 7 twist.
I do fully admit I'm definitely no ballistic expert. The same factors I mentioned could have affected Sean's dope as well???
I double checked what my velocities were the Hybrids were doing 3198 avg and the 147s were at 3185 I also had these speeds input to my calculator I'm not sure it would have been so obvious at shorter ranges such as 1000 but it really showed at 1400.
According to bergers twist calc. 4000 ft elevation at that speed and at around 90 degrees my 8 twist should easily achieve max BC
According to bergers twist calc. 4000 ft elevation at that speed and at around 90 degrees my 8 twist should easily achieve max BC
I was able to run some of these Today in my 8twist 26" saum
using Retumbo in Rem Brass.
ran a ladder @ 400 and kept them in about 1.5"
maxed out at around 62 grains and 3135
nice flat node around 61 grains at 3100
ill report back when I have a chance to shoot them at distance
to see if I'm loosing BC from the 8 twist.
using Retumbo in Rem Brass.
ran a ladder @ 400 and kept them in about 1.5"
maxed out at around 62 grains and 3135
nice flat node around 61 grains at 3100
ill report back when I have a chance to shoot them at distance
to see if I'm loosing BC from the 8 twist.
I think that you will be fine. Unless you are shooting a bullet with a really thin jacket, the extra twist should not affect your results with the 140s and could help stabilize things. There was a study I read about that dealt with extra twist vs. results and found that extra twist did not negatively affect accuracy unless the bullets used were thin jacketed varmint bullets. I do not know exactly where that test info is or would post it for you.
AB/Litz would be your source for the info on fast twist rates. I will have to run through my material once I get home, and post where you can find it.
If you run the Berger Twist Rate Stability Calculator, you can see what is going on in terms of stability and potential BC loss if things are not optimal. [h=2]http://www.bergerbullets.com/twist-rate-calculator/[/h] I have been trying to get more of the barrel manufacturers to put more fast twist 6mm & 6.5mm barrels on the shelf, and none of them have been real receptive at doing it. With the115 grain 6mm and 150 grain 6.5mm bullets, the older slower twist rates are not cutting it!
If you run the Berger Twist Rate Stability Calculator, you can see what is going on in terms of stability and potential BC loss if things are not optimal. [h=2]http://www.bergerbullets.com/twist-rate-calculator/[/h] I have been trying to get more of the barrel manufacturers to put more fast twist 6mm & 6.5mm barrels on the shelf, and none of them have been real receptive at doing it. With the115 grain 6mm and 150 grain 6.5mm bullets, the older slower twist rates are not cutting it!
thanks mate, my 6.5x47l has a .250 freebore would be ideal for these I single load, running the numbers through JBM even at 2720 velocity that you got they have a significant advantage over the 139 scenars I'm currently using if they group well. The berger twist calculator for 8 twist at sea level however is in the 1.4 range not looking so good....
We discussed going to a tighter twist on 6.5 barrels with Frank at Bartlein awhile back. He said at 2600 fps, his numbers showed the 150s would need a 1:7.52" at minimum and that Hornady is also recommending a 1:7.5" minimum for the 147s. If 1:7.5 is the minimum, we figured it made sense to play it safe and go a little tighter. He confirmed that going with the 7 twist was fine and mentioned that all the 6.5mm barrels they've been doing for Spec Ops and the AMU have been straight 1:7" twist as well. In regards to results with the 7 twist on bullets lighter than the 147-150 range, he had a Scout Sniper instructor from Camp Pendleton send him photos of his results with 139 Lapua Scenars and it apparently hammered.
Looking back the last year or two, it seems there's an upward trend in heavier, high BC projectiles and a corresponding need for barrels with faster twist rates. As bullet manufacturers continue to push the BC envelope, it'll be interesting to see what comes next.
Looking back the last year or two, it seems there's an upward trend in heavier, high BC projectiles and a corresponding need for barrels with faster twist rates. As bullet manufacturers continue to push the BC envelope, it'll be interesting to see what comes next.
IMHO, Sierra has a tendency to state that faster twists are required, but I think the more customary twists may still be adequate at the higher velocities available from the longer barrels.
If I am correct, Sierra's tendency is likely based on their inability to control/predict what length barrel and/or which chambering is going to be in use by the customer. After all, this bullet will fit a range of chamberings including the 6.5 Grendel as well as the 6.5-284, and even the 6.5 SAUM.
So capabilities vary broadly, and I think something like my own 28" 1:8" .260 Rem just may be effective with the 150SMK.
Anyhoo, I'll be watching the preliminary efforts; and then, I'll probably try a box's worth for pressure and stability testing at various charge levels. It may even turn out that I'll be quite able to avoid max/near max charges.
In fact, I suspect that this bullet will highlight the performance of H-4831 in the .260, thus reducing the insane demand on H-4350.
Greg
If I am correct, Sierra's tendency is likely based on their inability to control/predict what length barrel and/or which chambering is going to be in use by the customer. After all, this bullet will fit a range of chamberings including the 6.5 Grendel as well as the 6.5-284, and even the 6.5 SAUM.
So capabilities vary broadly, and I think something like my own 28" 1:8" .260 Rem just may be effective with the 150SMK.
Anyhoo, I'll be watching the preliminary efforts; and then, I'll probably try a box's worth for pressure and stability testing at various charge levels. It may even turn out that I'll be quite able to avoid max/near max charges.
In fact, I suspect that this bullet will highlight the performance of H-4831 in the .260, thus reducing the insane demand on H-4350.
Greg
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Stpilot12
My 6.5 is the x47, not the Creedmoor, but with H4350 and the 147gr ELDs, I haven’t found powder compression to be excessive, and my 8” twist Criterion barrel really likes them. Here’s 5 shots at 100 yards.
John
John
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BallisticPrimate and XLR308