Range Report Twist and 178 hornady bthps

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ARS031

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Dec 19, 2009
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#1
Hey guys,

I picked up a FN SPR A2 24" 1:12 from Mike @ tac coord. I wont be back from playing out east for another month or so, but I want to have some good ammo waiting for me when I get back. (dont feel like hand loading right when I get off the plane)

I peeked around here a bit for guys giving out info on running these rounds down a 1:12 and couldnt find a lot.

Bryans book states that at nominal and worse conditions, the bullet wont stabilize well.

Does anyone have any hard shooting data that would sway me away from buying up 500 of these rounds to put through my SPR?

I will be shooting the gun from 100-1400m and am hoping I can count on the round in my setup.

Thanks guys.
 
#2
Re: Twist and 178 hornady bthps

1400m is going to be quite a challenge for a .308
I shoot a factory bbl FN SPR and have setteled on the 175 SMK's and have some load dev rounds with the 155's loaded up.. which due to the slower twist rate and higher BC may be the way to go?
 
#3
Re: Twist and 178 hornady bthps

I have shot my SPR to 1300 yards (not meters) this summer with decent results, but you can't buy an equivalent load. Out to 1000 you will be okay(not great) with a factory 175gr load like Black Hills, but further out than that and you have to handload.
 
#5
Re: Twist and 178 hornady bthps

Appreciate all the input, looking specifically for anyone who has encountered stability issues/lack thereof with the 178 bthp match hornady's in a 1:12.
 
#6
Re: Twist and 178 hornady bthps

Not sure on the difference in the bullet construction but I run the 178 a-maxs thru my LTR 1/12 twist with a 20" tube they stabilize fine out to 1k but not much father than that. My load is 44.5 gr of RL-15 Hornady Match brass with a BR2 primer. It holds 1moa out to 600y when I do my part correctly.
 
#7
Re: Twist and 178 hornady bthps

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: ARS031</div><div class="ubbcode-body">Appreciate all the input, looking specifically for anyone who has encountered stability issues/lack thereof with the 178 bthp match hornady's in a 1:12. </div></div>

I shoot the 178's out of a 1:12 and have had no stability issues. I haven't shot them past 1000m yet.
 
#9
Re: Twist and 178 hornady bthps

I had great luck with a 1-12 with the 178s. I pushed them kind of slow but they still made it to 1000yds. They would go subsonic at like 950yds. 44gr Varget and 178s going around 2525fps.
 
#10
Re: Twist and 178 hornady bthps

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: ARS031</div><div class="ubbcode-body">Bryans book states that at nominal and worse conditions, the bullet wont stabilize well.</div></div>Given 'bad conditions' no bullet stabilizes well.

Does 'nominal' mean less than the ideal twist-rate, and 'worse conditions' mean negative environmental factors like high pressure and cold weather?

You can't decide on a twist rate for a bullet based only on the bullet. Because the bullet itself and/or the bullet weight alone is not of stand-alone importance with regard to twist rate. The 178 Hornady was not designed with an extremely long bearing surface for its caliber, so based on the parameters of your question the answer is: No. But you need to also take into account velocity, temperature and presure, and whether you intend to shoot it into 90% of its supersonic range.

FYI: I shoot 180VLDs at 2700fps out of a 24" bbl with a 12 twist, at sea level, to beyond 1200 yards.
 
#11
Re: Twist and 178 hornady bthps

I've seen the 178 absolutely excel out of a 12 twist 20" barreled Remington LTR, both at short range and out past 1000 yards. It remained stable and predictable transonic and subsonic. The bullet proved to be easy to load for - just a standard load of H4895 in a Winchester case with a CCI primer - no load development at all done to get it down sub-.75 MOA.

If you have poor results with your new stick and this bullet, it won't be the bullet's fault.
 
#12
Re: Twist and 178 hornady bthps

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: _9H_Cracka</div><div class="ubbcode-body">I've seen the 178 absolutely excel out of a 12 twist 20" barreled Remington LTR, both at short range and out past 1000 yards....If you have poor results with your new stick and this bullet, it won't be the bullet's fault. </div></div>Perhaps that is what I should have said.
 
#13
Re: Twist and 178 hornady bthps

In Bryan's book, he defines the different conditions that are associated with the unstable/nominal/stable Sg factors for various twist rates and a given projectile. He is also careful to point out that the values given don't necessarily mean that a given projectile will be totally unstable from a specific twist barrel. The "nominal" Sg value he presents for a given twist rate and projectile is 1.4, which is fairly conservative, and is used as a recommendation rather than to suggest that if you go below an Sg of 1.4 a projectile will be totally unstable.

As another example to _9H_Cracka's using the 178, I had a Sig 556 DMR with a 21" 10-twist barrel. On paper, it should not have stabilized 77 gr SMKs very well at all (predicted Sg of 1.151 at 2750 fps). However, I routinely used it with that round out to 600 yd with no detectable issues at all. I'm not saying it was optimal, but it worked, demonstrating there can be a certain amount of leeway in twist rate numbers with a specific rifle.
 
#14
Re: Twist and 178 hornady bthps

Thats good news for me, appreciate you guys taking the time to share your experiences.

Looks like Ill be buying some of the factory stuff to try out and then if that works out well for me Ill start loading and see what I can come up with.

Thanks to everyone who contributed.
 
#16
Re: Twist and 178 hornady bthps

47.8 alliant 2000 mr 40/1000's off lands with 178 amax out of a sps tactical which has a 1:12 gives me 1/2 moa out to 500 on my worst day. Gotta love the amax
 
#17
Re: Twist and 178 hornady bthps

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Aimsmall55</div><div class="ubbcode-body">47.8 alliant 2000 mr 40/1000's off lands with 178 amax out of a sps tactical which has a 1:12 gives me 1/2 moa out to 500 on my worst day. Gotta love the amax
</div></div>

What's COAL on that?
Any pressure problems?
 
#18
Re: Twist and 178 hornady bthps

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: GlockandRoll</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Aimsmall55</div><div class="ubbcode-body">47.8 alliant 2000 mr 40/1000's off lands with 178 amax out of a sps tactical which has a 1:12 gives me 1/2 moa out to 500 on my worst day. Gotta love the amax
</div></div>

What's COAL on that?
Any pressure problems?
</div></div>

I don't have my data book with me but I believe it's 2.895" if my memory serves me correct. No pressure signs at all. I shoot the 185 vlds with 47.0 grains out of a Gap Crusader at 2.830" with no pressure signs either. Is truly an awesome powder for bigger bullets. Gap has a 22" barrel and I'm at 2710 fps with the 185's.
 
#19
Re: Twist and 178 hornady bthps

Thanks, I'll be interested in checking that out.. are you compressing the powder at all?
I'm trying to figure out where the best place to start with 155 scenars would be for my 24" 12" twist bbl.
 
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