98 220 swift
New member
Just bought a 24" upper with a Wilson 1-8" twist barrel. Wondering what bullet weights to try. My 1-9" liked 52gr the best. Figure the 1-8 will like 60-68??. Any good loads to try?
1-8" twist 223 ar barrel
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JeepHammer
Moderator
1/8" has traditionally 'Liked' 55 grain and up.
That's a fast twist rate and traditionally you need a longer bearing surface (the part of the bullet that contacts the rifling = Bearing Surface)
To hold the rifling with a twist rate that fast.
My 1/8" barrels REALLY like Hornady 60 grain V-Max bullets for some reason,
While the 1/9" 'Likes' the 55 grain V-max better.
You wouldn't think a single inch would make much of a difference, but it seems to in my rifles (Plural, more than one with each barrel).
I just built a couple 1/8" and they really came in when I switched to 60 grain bullets.
I'm sure everyone will have different experences depending on all the other variables, just personal experence I'm writing about.
That's a fast twist rate and traditionally you need a longer bearing surface (the part of the bullet that contacts the rifling = Bearing Surface)
To hold the rifling with a twist rate that fast.
My 1/8" barrels REALLY like Hornady 60 grain V-Max bullets for some reason,
While the 1/9" 'Likes' the 55 grain V-max better.
You wouldn't think a single inch would make much of a difference, but it seems to in my rifles (Plural, more than one with each barrel).
I just built a couple 1/8" and they really came in when I switched to 60 grain bullets.
I'm sure everyone will have different experences depending on all the other variables, just personal experence I'm writing about.
98 220 swift
New member
Good thing I bought a box of these a few weeks ago. Care to share load data?
4runnerman
New member
I just got mine about2 months ago, but it's a 1-7 twist 22 inch Target bull barrel. Right now it loves 60 gn Hornady V max, Just picked up a few hundred 69 Serria BTHP. Been very windy and raining every weekend since then, so no input yet.
LC Brass, CCI 41, COAL 2.260" small bass sizing die, no crimp, neck button reduced a bit to get a tighter grip without the crimp.
55gr V-Max, 24.9gr H335 (25.3gr also showed promise).
H335 did not perform well with heavier 69/77gr bullets.
69gr SMK 25.2-25.4gr Varget
77gr SMK 23.3-23.5gr Varget
it's gotta be me, but almost without exception the 55 and 69gr loads above have repeatidly produced 4 of 5 under 1/2", but I always seem to have one outlyer.
55gr V-Max, 24.9gr H335 (25.3gr also showed promise).
H335 did not perform well with heavier 69/77gr bullets.
69gr SMK 25.2-25.4gr Varget
77gr SMK 23.3-23.5gr Varget
it's gotta be me, but almost without exception the 55 and 69gr loads above have repeatidly produced 4 of 5 under 1/2", but I always seem to have one outlyer.
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JeepHammer
Moderator
I find the lighter weight 'Boat Tail' won't do as good a job as the same weight flat base, in general terms.
My *Opinion* is the boat tail reduces bearing (contact surface) with the rifling when you try to push them really hard (around 3,100 to 3,300 FPS) and there simply isn't enough load bearing surface to hold the rifling.
Recovered bullets show 'Stripping', look more like they were fired through a smooth bore, with the exception they are undersized, or missing the jacket entirely.
Don't know why, I suspect its the bullet manufacturing process,
But Hornady & Sierra Match Kings seem to do the best job,
With Hornady being my personal favorite since the do such a great job on 'Varmints'.
Get up to that 60 or 62 grain mark, the boat tail doesn't seem to make as big a difference as it does with 50 to 55 grain bullets in fast twist barrels.
What do I know, I still have .223 rifles with 1/14 & 1/12 barrels that seem to shoot fine with 45 to 55 grain varmint bullets...
No one would be caught dead these days with such a slow twist rate!
My *Opinion* is the boat tail reduces bearing (contact surface) with the rifling when you try to push them really hard (around 3,100 to 3,300 FPS) and there simply isn't enough load bearing surface to hold the rifling.
Recovered bullets show 'Stripping', look more like they were fired through a smooth bore, with the exception they are undersized, or missing the jacket entirely.
Don't know why, I suspect its the bullet manufacturing process,
But Hornady & Sierra Match Kings seem to do the best job,
With Hornady being my personal favorite since the do such a great job on 'Varmints'.
Get up to that 60 or 62 grain mark, the boat tail doesn't seem to make as big a difference as it does with 50 to 55 grain bullets in fast twist barrels.
What do I know, I still have .223 rifles with 1/14 & 1/12 barrels that seem to shoot fine with 45 to 55 grain varmint bullets...
No one would be caught dead these days with such a slow twist rate!
My 1:8 twist Les Baer Super Varmint .223 with an 18 inch barrel shoots 52 grain SMKs, 69 TMKs, 77 TMKs and 77 Berger Match bullets under 0.4 inches on average at 100 yards for 5 round groups. I don't think that your 1:8 will be all that sensitive to bullet weight but it may have preferences for bullet shape. The 6 inch barrel length difference should give your rifle a higher muzzle velocity for a given powder load so my best loads won't be of much value to you. However, the powder preferences might.
The 69 grain TMKs have the best overall average at 0.283 with N140 powder for all the loads fired with that powder/bullet combination with a best load with a particular velocity and seating depth averaging 0.249.
The 69 TMKs have an overall average is 0.315 with Reloader 15 powder.
The 69 TMKs have an overall average 0.363 with CFE223 powder with a best load averaging 0.227.
52 grain SMKs overall average is 0.352 with N140 powder.
77 TMKs overall average is 0.360 with CFE233 with a best load averaging 0.202.
77 TMKs overall average is 0.363 with Reloader 15 with a best load averaging 0.331.
The best 69 SMKs overall average is 0.460 with N140 with a best load averaging 0.360
The best 77 SMKs overall average is 0.418 with Reloader 15 with a best load averaging 0.341.
As you can see, the higher BC bullets in 69 and 77 grains seem to shoot more accurately in the Les Baer even at 100 yards.
I haven't shot too many combinations with the lighter 52 grain SMK bullets but the accuracy is slightly better than the best loads of the 69 and 77 grain SMK bullets. The sample size is not large enough for statistical comparisons.
I've also tried 70, 73 and 75 grain Berger bullets with N140 powder and they averaged under 0.45 inches at 100 yards for the few loads I tried. The best loads for each were under 0.35 but the sample sizes were also too small for statistical comparisons.
The 69 grain TMKs have the best overall average at 0.283 with N140 powder for all the loads fired with that powder/bullet combination with a best load with a particular velocity and seating depth averaging 0.249.
The 69 TMKs have an overall average is 0.315 with Reloader 15 powder.
The 69 TMKs have an overall average 0.363 with CFE223 powder with a best load averaging 0.227.
52 grain SMKs overall average is 0.352 with N140 powder.
77 TMKs overall average is 0.360 with CFE233 with a best load averaging 0.202.
77 TMKs overall average is 0.363 with Reloader 15 with a best load averaging 0.331.
The best 69 SMKs overall average is 0.460 with N140 with a best load averaging 0.360
The best 77 SMKs overall average is 0.418 with Reloader 15 with a best load averaging 0.341.
As you can see, the higher BC bullets in 69 and 77 grains seem to shoot more accurately in the Les Baer even at 100 yards.
I haven't shot too many combinations with the lighter 52 grain SMK bullets but the accuracy is slightly better than the best loads of the 69 and 77 grain SMK bullets. The sample size is not large enough for statistical comparisons.
I've also tried 70, 73 and 75 grain Berger bullets with N140 powder and they averaged under 0.45 inches at 100 yards for the few loads I tried. The best loads for each were under 0.35 but the sample sizes were also too small for statistical comparisons.
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JeepHammer said:
Bryan Litz pointed out in his book that boattails are harder to manufacture with symmetry as perfect as a square base. Since they dwell in the muzzle blast briefly between the time the bearing surface clears the muzzle and the heel of the boattail clears the muzzle, that high speed gas blast has that extra time to deflect unevenly and introduce drift to the bullet trajectory. For the same reason, even the smallest asymmetry in the crown will also have its adverse influence exaggerated by a boattail. Another issue is that the shorter bearing surface allows the bullet to tilt in the bore more. That moves the CG further off the bore axis introducing drift at exit tangent to the point on the muzzle the CG was closest to and in the direction of rotation. So it becomes more important to load ammunition without runout when you use boattails. Their only advantage is higher BC and less wind drift. Otherwise we'd all shoot square base bullets like the short range benchrest shooters do.
If you get stripping, though, that's running the bullet too hard for the twist rate. I assume it is something light that would prefer a 12" twist or so. You might be able to shoot something like the 77's at 2800-2900 fps without introducing that issue, but you've already had a problem with those. Could also be the gun's barrel doesn't like their barrel time or some such thing, though. Try the 64 grain Berger flat base and see how those do.
98 220 swift,
Bullet length actually has more influence on stability than weight. You could, for example have both a jacketed lead bullet and a copper solid the same weight, but because copper is less dense than lead, the solid will be longer and can be unstable when the jacketed lead bullet was stable. A flat base bullet of a given weight is generally shorter than a boattail the same weight and therefore is more stable for a given twist. This is another reason flat base bullets are sometimes better shooters. In my 222 Remington (14" twist) a flat base Hornady 50 grain soft point bullet always grouped significantly more tightly than the 52 grain Sierra match boattail. It was length and tilt, both, in that instance.
Fifty or sixty years ago bullets were all constructed about the same way, jacket and core and tangent ogive Spitzer noses, and other than the difference between boattail and flat base, you could count on them being similar enough that using weight as the sole stability criterion was close enough. Today, with different materials and longer high BC secant ogive shapes and so on, weight is not a great stability criterion by itself.
JeepHammer
Moderator
Uncle Nick,
Didn't read the article you refer to, but I've run into the muzzle crown issue before several times...
I call it 'Gas Jetting' when there is a gouge in the crown.
On high speed film you can Clearly see the damaged crown throw a concentrated gas jet off one spot as the bullet exits,
and it takes a remarkably small gouge to allow the gas jet to happen.
I kind of wonder if that's the reason for the 11* crown that became so popular a few years back, giving the exit gas free room to expand away from the bullet base...
Long range rifles do much better with that 11* crown (which is harder to damage than some other crowns) and heavy boat tails, I believe its the heavy bullets have more bearing surface (internal ballistics) combined with the 11* crown dissapating exit gasses allows for proper exteror ballistics to happen.
I could be wrong, but I've not found a good argument against my theroy/observations.
The first thing I tell people trying to shoot long range or hyper accurately to do is throw away the sectional cleaning rod!
Nothing quite like a steel sectional cleaning rod, stuffed into the muzzle, to put lenier gouges into the crown!
Bore snake or clean from the chamber with a ONE PIECE rod, adapters/tools made from something that CAN NOT gouge or scratch the bore/crown...
Nothing quite like seeing a guy spend $500 getting his rifle shooting one hole 10 shot groups,
Then watching him stick a military surplus sectional cleaning rod down the muzzle and hearing that 'Chink, Chink, Chink' as the rod sections gouge the crown!
Didn't read the article you refer to, but I've run into the muzzle crown issue before several times...
I call it 'Gas Jetting' when there is a gouge in the crown.
On high speed film you can Clearly see the damaged crown throw a concentrated gas jet off one spot as the bullet exits,
and it takes a remarkably small gouge to allow the gas jet to happen.
I kind of wonder if that's the reason for the 11* crown that became so popular a few years back, giving the exit gas free room to expand away from the bullet base...
Long range rifles do much better with that 11* crown (which is harder to damage than some other crowns) and heavy boat tails, I believe its the heavy bullets have more bearing surface (internal ballistics) combined with the 11* crown dissapating exit gasses allows for proper exteror ballistics to happen.
I could be wrong, but I've not found a good argument against my theroy/observations.
The first thing I tell people trying to shoot long range or hyper accurately to do is throw away the sectional cleaning rod!
Nothing quite like a steel sectional cleaning rod, stuffed into the muzzle, to put lenier gouges into the crown!
Bore snake or clean from the chamber with a ONE PIECE rod, adapters/tools made from something that CAN NOT gouge or scratch the bore/crown...
Nothing quite like seeing a guy spend $500 getting his rifle shooting one hole 10 shot groups,
Then watching him stick a military surplus sectional cleaning rod down the muzzle and hearing that 'Chink, Chink, Chink' as the rod sections gouge the crown!
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typo fix
Yeah, it's a good idea to put a slight radius on the edges of the segments of one of those rods if you just have to use it. Some fellows at the CMP forum reported a lengthy test on Garand barrels running these rods into them and claimed there was no damage. But I bought a Columbian surplus Mauser 98 back in the 80's that had a muzzle heavily worn on only the bottom side, where the rod would bear when the person cleaning the gun rested it on the toe of its butt stock. And the rod that came with it was solid! Dirt and grit? Softer steel? Something was happening.
I've seen muzzle crowns simply off-perpendicular to the bore. Someone wrote an article about the Manson crowning tool in which they described getting some of the cost of it back by charging $15 to recrown club member's rifles, and doing a number of them and about half grouping tighter as a result. Was that correcting wear due to poor handling or correcting factory imprecision? I don't know, but suspect the latter.
Litz's comments on boattails came from his book, Applied Ballistics for Long Range Shooting.
Harold Vaughn did some extensive experimenting with muzzle crowns. He concluded the angle made absolutely no difference, but the crown did have to be perfectly symmetrical around the bore axis. He suggested the source of that 11° angle number was a misunderstanding of aerodynamics due to someone having been told it was the angle that produced the least drag on an automobile. Vaughn had been Head Aeroballistician at Sandia National Labs, so he was tuned to those things.
I can tell you that a perfectly square crown is easiest to get right because a square cut taken on a lathe has no way to be asymmetric. As soon as you put an angle on it, though, the point of the cone it cuts has to be perfectly centered in the bore axis. But for a square cut the bore can be turning eccentrically in the lathe and the result will still be symmetrical. Adding a slight bevel offers some ding protection. It also makes the edge of the crown stronger and more resistant to muzzle blast wear. But you can cut a square recessed crown for the ding protection and muzzle blast will tend to erode it evenly.
I usually cut a square crown and angle its edge with a ball lap to recess it for protection. It only takes about 10 minutes to lap it, and a ball self-centers in the square cut crown. The outside gets a chamfer, of course.
Yeah, it's a good idea to put a slight radius on the edges of the segments of one of those rods if you just have to use it. Some fellows at the CMP forum reported a lengthy test on Garand barrels running these rods into them and claimed there was no damage. But I bought a Columbian surplus Mauser 98 back in the 80's that had a muzzle heavily worn on only the bottom side, where the rod would bear when the person cleaning the gun rested it on the toe of its butt stock. And the rod that came with it was solid! Dirt and grit? Softer steel? Something was happening.
I've seen muzzle crowns simply off-perpendicular to the bore. Someone wrote an article about the Manson crowning tool in which they described getting some of the cost of it back by charging $15 to recrown club member's rifles, and doing a number of them and about half grouping tighter as a result. Was that correcting wear due to poor handling or correcting factory imprecision? I don't know, but suspect the latter.
Litz's comments on boattails came from his book, Applied Ballistics for Long Range Shooting.
Harold Vaughn did some extensive experimenting with muzzle crowns. He concluded the angle made absolutely no difference, but the crown did have to be perfectly symmetrical around the bore axis. He suggested the source of that 11° angle number was a misunderstanding of aerodynamics due to someone having been told it was the angle that produced the least drag on an automobile. Vaughn had been Head Aeroballistician at Sandia National Labs, so he was tuned to those things.
I can tell you that a perfectly square crown is easiest to get right because a square cut taken on a lathe has no way to be asymmetric. As soon as you put an angle on it, though, the point of the cone it cuts has to be perfectly centered in the bore axis. But for a square cut the bore can be turning eccentrically in the lathe and the result will still be symmetrical. Adding a slight bevel offers some ding protection. It also makes the edge of the crown stronger and more resistant to muzzle blast wear. But you can cut a square recessed crown for the ding protection and muzzle blast will tend to erode it evenly.
I usually cut a square crown and angle its edge with a ball lap to recess it for protection. It only takes about 10 minutes to lap it, and a ball self-centers in the square cut crown. The outside gets a chamfer, of course.
98 220 swift
New member
Thanks for the replies. I shot the rifle and it liked 52 and 68 gr bullets. the 68s where a little better but not much. It looks like I need to try some other weights as well. I am just used to my other AR with its 1-9" barrel and it only liked 52gr. Everything else was a waste of time. I figured this one would like heavier bullets.