Reply With QuoteNo.... the LWH has a 1:9 twist and cannot stabilize a 77gr bullet
Has anybody tried Sierra MatchKing 77 gr (or similar) bullets in the Savage Lightweight Hunter .223 Rem? If so, did you get the expected accuracy from the 77 gr bullet?
I've read (here, I think) that Savage .223 rifles are optimized for the 69 gr Matchking. I'm wondering if the LWH will stabilize the 77 gr Matchking.
No.... the LWH has a 1:9 twist and cannot stabilize a 77gr bullet
.22LR * 6.5x47 Lapua * .223 Rem * .308 Win * 260 Rem * Large Cojones!
[I]"I can prove anything by statistics except the truth."[/I]
Actualy the 77 gr SMK's do fine in a 1 in 9 twist 223. When I got my 10 PC in 223 Savage tested the rifle with 77SMK's loaded in fed ammo. I thought this was interesting and I did some playing myself. I found that with 4895 I got the best accuracy. You will have a hard time finding load data for this bullet do to Sierra designed this bullet for 1 in 9 twist AR15's, and the load data is for them. When I talked to Rich Macholtz at Sierra, he told me "They never thought anyone would use this bulet in a bolt action," so they never printed any load data for it. I used the AR15 data, but I dont recamend it and if you do you do so on your own. The other problem with the 77's is they come in boxs of 50, and if you figger the price they are quite pricecy.
For the price, the Hornady 75 Match is hard to beat. It's less money, has a higher B.C., and can be bought in packs of 600 if you wish. They shoot right along with my 75 AMAX's at 300 yards. In my BVSS 223 barrel they'll do 1" groups at 300 yards with 24.5 grains of Varget.
Kevin
I'm confused. I thought Sierra specifies 1:8 or faster twist for .224 77 gr Matchking.Originally Posted by 82boy
Are you saying .223 rounds for AR-15s don't work well in bolt actions for some reason? Does this have to do with cartridge overall length? Would a 77 Matchking loaded to a custom length for a bolt action work fine?When I talked to Rich Macholtz at Sierra, he told me "They never thought anyone would use this bulet in a bolt action," so they never printed any load data for it. I used the AR15 data, but I dont recamend it and if you do you do so on your own.
What motivated my original question is I have a lot of Black Hills .223 77 gr Matchking, which is designed for AR-15s. I was wondering if these rounds would work well in a Savage Lightweight Hunter .223, with 1:9 twist.The other problem with the 77's is they come in boxs of 50, and if you figger the price they are quite pricecy.
I know Sierra specifies 1:8 but I've heard anecdotally that 1:9 often works, too. I'm trying to decide if it's worth the risk of getting the Lightweight Hunter in .223, knowing that Sierra says 77 gr Matchking requires 1:8 twist.
Seirra mush have changed the specks on the bullet, I see on the web site it list for a 1 in 7 or 8 twist barrel. Just because a maker puts a RECAMENDED tist rate doesn't mean that it will not work with slower twist, the only way to tell is to try it. Prime example, Savages 243's are a 1 in 9.25 twist, many have had great luck with shooting 107 SMK's wich say a min twist rate of 1 in 8.I'm confused. I thought Sierra specifies 1:8 or faster twist for .224 77 gr Matchking.
It has nothing to do with it not working, the intended design was for it to be used in a ar rifle. The bullet was designed to feed in an autoloader, and function from a magazine. It was also designed in responce to what the AR people wanted. Sierra figgured that since they had the 69gr and the 80gs 22 they have everything covered. They was just suprised to see someone use it in a bolt gun. A bolt gun can withstand higher pressures than a autorifle. Yes the round works in a bolt rifle, if it didn't Savage would have never tested the round in the rifle.
The absolute worst thing you can ever do is pick out a round and buy a rifle to shot it. With that said never buy a rifle to shoot one type of bullet or loaded round, even if it identicaly matchs the specks. Barrel have there own peosonalitys, for example you can take two barrels made right after another by the same person, with the same tooling and they will act entirly different. Let the barrel tell you what it likes, NEVER force feed a barrel a bullet that you like. Even if the barrel was a 1 in 7 twist it may not like the 77gr SMK, and it may shoot a 69 gr SMK better, it is just how it is. When dealing with button rifled barrel the twist can verry from barrel to barrel some will be a bit faster than advertised, and some will be a bit slower, this could also determin if a bullet will work in a barrel, or not. All in all, if you like the gun, (Regardless of if it will shot a certain bullet.) buy it, if you have to have something that will shoot a certain bullet, then buy the gun that the bullet was designed for, a AR15 with a 1 in 7 twist. (And that is no garentee that it will work.)
Sundo,
If you want to try some ,buy a box. Or even better, post a wanted add for some and ask if you can just buy 12 or 15 to test out.
You may have to load them on the hot side to get enough rpms to stabilize them. I personally never tried 77's but 75 berger vld's and a-maxes work fantastic out of my model 12 .223.
Greatest excuse in the world for the household finance manager. " Honey, I have all these bullets just laying around, If I buy a gun to shoot them I won't be spending Sooo much on reloading components" If anyone trys it let me know how it worked. My CFO knew I was full of it from the beginning.
But either can handle rounds loaded to SAAMI pressures. The 77SMK was designed as a compromise bullet, better BC than the 69SMK but conceded BC to the 80SMK in order to have an ogive short enough to fit in an AR magazine. If you aren't limited to the 2.26" magazine of an AR-15, there's really no reason to load the 77SMK over the 80.
The differences in load data between the bolt-action/single shot and the AR-15 data is not the peak pressure necessarily. It is the volume of gas produced by the AR-15 loads is moderated to keep from overgassing the rifle and messing up its reliability. In some cases, this is done with a reduced charge, in others with a faster powder. In either case the reduction in gas does create a reduction in velocity, regardless of the peak pressure.
We have had several competitors try the 80gr MK in their Savage 9 twists at 600 yds shooting F-class. They don't make it! They shoot all over the paper, key holes, some don't even make it to the 600 yd. line. You can not make the 80gr. shoot fast enough to get the required 250,000 rpm to stabilize the bullet. Some times what works out to 300 falls apart out there where things get interesting.
Best regards,
Grit
If the bullet is good at 300 and not at 600 the problem isn't the rate of twist, its the velocity of the bullet and dynamic (not gyroscopic) instability. Essentially the bullet is going transonic and is being upset by the transonic shockwave. A faster rate of twist *can* help with that problem, but the best solution is to send the bullet faster, ensuring that it is above 1500fps or so at the target range.
From what I've learned about External Ballistics, bullets must deal with their Center of Pressure [CP] being in front of their Center of Gravity [CG]. That is what causes destabilization while in flight. In order to stabilize the bullet, it is spun around its longitudinal (leading to trailing) axis. The spinning mass makes the bullets length axis resistant to the destabilizing overturning torque of the CP being in front of the CG. In In the transonic region (~ 880 fps to 1320 fps), the centre of pressure (CP) of most bullets shifts forward as the bullet decelerates. Staying above transonic speeds would reduce the need to "spin" the bullet faster to maintain stabilization. In that respect, I think helotaxi and I agree. Where I would probably diverge would be the "cure". Assuming reasonable target loads on the SMK 77gr with a MV of 2600 fps, we don't hit transonic speeds (1320 fps - the highest of that range) until beyond 650 yards (further out if you conceed a faster MV). So experiences between 300 and 600yards, while differing are more likely due not to transonic destabilization, but to gyrosopic destabilization. My "cure" would be to use a proper twist rate of say 1:8".
There have been several folks who say thier factory Savage rifle barrel (stamped at 1:9" twist) will shoot these 77gr SMKs successfully. Since twist rates are approx. in these factory barrels, I'd suggest that they may find that thier particular barrel is approaching 1:8" twist (if measured). This is certainly within the realm of possibility as production rifle barrels actual twist can vary - particularly those with button cut rifling.
Just my 2 cents...
.22LR * 6.5x47 Lapua * .223 Rem * .308 Win * 260 Rem * Large Cojones!
[I]"I can prove anything by statistics except the truth."[/I]
Not to be a stick in the mud but no such thing as button cut rifling. It is either button or cut. Button displaces the metal and cut removes it.
"And you shall know the truth, and the truth shall make you free.” John 8:32 (New King James Version)
The force acting on the center of pressure is proportional to bullet velocity. As velocity decays that force decreases. As that force decreases, fewer RPM are required to overcome that force. Bullet RPM decays at a much slower rate than velocity and the stability index increases with range. As such if the bullet is stable at 100yds, it will be stable (at least gyroscopically) all the way to the target. FWIW, Ballistic FTE shows the 77gn SMK fired with an MV of 2600fps entering the transonic region right at 600yds. A small variance in MV is all it takes at that point to make things very unpredictable.
From what I've learned about External Ballistics, bullets must deal with their Center of Pressure [CP] being in front of their Center of Gravity [CG]. That is what causes destabilization while in flight. In order to stabilize the bullet, it is spun around its longitudinal (leading to trailing) axis. The spinning mass makes the bullets length axis resistant to the destabilizing overturning torque of the CP being in front of the CG. In In the transonic region (~ 880 fps to 1320 fps), the centre of pressure (CP) of most bullets shifts forward as the bullet decelerates. Staying above transonic speeds would reduce the need to "spin" the bullet faster to maintain stabilization. In that respect, I think helotaxi and I agree. Where I would probably diverge would be the "cure". Assuming reasonable target loads on the SMK 77gr with a MV of 2600 fps, we don't hit transonic speeds (1320 fps - the highest of that range) until beyond 650 yards (further out if you conceed a faster MV). So experiences between 300 and 600yards, while differing are more likely due not to transonic destabilization, but to gyrosopic destabilization. My "cure" would be to use a proper twist rate of say 1:8".
To begin with, I was talking about the 80gr MK not the 77. Regardless a 1:9 twist in a .223/556 is not fast enough to stabilize the 80MK. The case of the 223/556 is to small in capacity to drive the bullet (80gr MK) fast enough to use a slower twist rate. That is why the MFG recommends a 7 twist for the 80MK.
Best regards,
Grit
You're right earl. Sorry to be too "loose" in my using the work "cut" in the wrong context here as it confuses button and cut rifling methods (I was using it in context of how the rifling was cut using the button method as opposed to the cut method of cutting the rifling in a barrel)...Not to be a stick in the mud but no such thing as button cut rifling. It is either button or cut. Button displaces the metal and cut removes it.
My bad (and apologies)
.22LR * 6.5x47 Lapua * .223 Rem * .308 Win * 260 Rem * Large Cojones!
[I]"I can prove anything by statistics except the truth."[/I]
Well... that isn't exactly what I was taught. Maybe you are smarter than the teacher (could be) and texts (I could have read them wrong?). I too used Ballistic (v2.5.6) and the transonic range was just at 650 yards - so I don't know how that could be different (maybe altitude diff?) I had to step the MV down to 2460 to get into transonic at 600 yards (that's a pretty big delta for a BR competitor).The force acting on the center of pressure is proportional to bullet velocity. As velocity decays that force decreases. As that force decreases, fewer RPM are required to overcome that force. Bullet RPM decays at a much slower rate than velocity and the stability index increases with range. As such if the bullet is stable at 100yds, it will be stable (at least gyroscopically) all the way to the target. FWIW, Ballistic FTE shows the 77gn SMK fired with an MV of 2600fps entering the transonic region right at 600yds. A small variance in MV is all it takes at that point to make things very unpredictable.
From what I've learned about External Ballistics, bullets must deal with their Center of Pressure [CP] being in front of their Center of Gravity [CG]. That is what causes destabilization while in flight. In order to stabilize the bullet, it is spun around its longitudinal (leading to trailing) axis. The spinning mass makes the bullets length axis resistant to the destabilizing overturning torque of the CP being in front of the CG. In In the transonic region (~ 880 fps to 1320 fps), the centre of pressure (CP) of most bullets shifts forward as the bullet decelerates. Staying above transonic speeds would reduce the need to "spin" the bullet faster to maintain stabilization. In that respect, I think helotaxi and I agree. Where I would probably diverge would be the "cure". Assuming reasonable target loads on the SMK 77gr with a MV of 2600 fps, we don't hit transonic speeds (1320 fps - the highest of that range) until beyond 650 yards (further out if you conceed a faster MV). So experiences between 300 and 600yards, while differing are more likely due not to transonic destabilization, but to gyrosopic destabilization. My "cure" would be to use a proper twist rate of say 1:8".
.22LR * 6.5x47 Lapua * .223 Rem * .308 Win * 260 Rem * Large Cojones!
[I]"I can prove anything by statistics except the truth."[/I]
My apology Grit.... I was kinda indirectly trying to make that same point (use a faster twist rate).
.22LR * 6.5x47 Lapua * .223 Rem * .308 Win * 260 Rem * Large Cojones!
[I]"I can prove anything by statistics except the truth."[/I]
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