By Mark V. Lonsdale
Premise: What’s more important – the bullet or the barrel twist?
I see more than a few rookie shooters on Facebook asking about the best load for a specific bullet but without knowing their barrel twist. Conversely, several asked about running a particular bullet in a barrel twist that is completely unsuited to that bullet weight.
To simplify this dilemma when getting into precision long range shooting, if you already own the rifle and know the barrel twist, then select a bullet that is best matched to that twist rate, either target or hunting bullet. And if you don’t know the twist, then mark a cleaning rod and measure how many inches it takes to make one full rotation as it is pushed into the bore.
As a practical example, in .308 Winchester most factory rifles are manufactured in 1:12” twist or 1:10” twist. The 1:12” barrels were intended for the 150, 165, and 168 grain bullets, target or hunting. The 1:10” were more suited to the heavier 180, 185, and 190 grain bullets. When the Marines requested a 175 grain SMK, it was thought that a better barrel twist would be 1:11.5” Since I own several rifles in all three barrel twists, and shoot them more than any other caliber, it is safe to state that the 168 SMKs shoot great in all three twist rates, but I have opted to running Bartlein 1:11.5” barrels in my newer .308s. This works great with both 168 and 175 SMKs. The 185 Juggernauts, 190 SMKs, 200 Hybrids, and 215 Berger Hybrids, definitely shoot better in the 1:10” twist that I have in my F-TR rifles and 300 WinMags. As with many long range shooters, I prefer 200 grain Hybrid bullets for 1,000 yard shooting, and 215 Hybrid or 210-220 SMKs out to 1,500 yards, in .30 caliber. After that we are into .338 or .375 country.
Robar .308 Win built on a Rem 700 action, Bartlein 1:11.5″ barrel, and McMillan A3-5 stock.
168 grain Sierra Matchkings from a 1:11.5″ barrel. Handloads on left, factory Federal Gold Medal Match on right
In the lighter calibers such as 6.5 Creedmoor, I’m running medium and heavy Palma 1:8” twist barrels but have found a significant difference in precision accuracy with various bullet weights. After considerable testing with 130, 140, 142, and 147 grain bullets, hands down my rifles prefer the 140 grain bullets. Consistent 0.5” groups don’t lie. So this was a case of barrel first and then find the right bullet.
PRS 6.5 Creedmoor with a 1:8″ Bartlein medium Palma barrel in a McMillan A6 stock, topped with a Leupold Mark 5HD 5-25x scope
Hornady 140 ELD-M (left) 142 SMK (right)
If you are planning on buying or building a custom rifle, you first select the bullet you wish to shoot and then match the barrel twist to that bullet. For example, for ELR shooting, the 400 grain Lazer Cutting Edge bullets in .357 CheyTac and the 550 grain Lazers in .416 Barrett have proven to be winners. For .338 Lapua Magnum, the choice may be the 300 Sierra Matchking or the Cutting Edge 275 Lazer – one jacked and one solid.
Running Cutting Edge 550 Lazers at the 2019 Ko2M
The general rule is that heavier bullets prefer faster twist barrels; and you can run even faster twist barrels with solid bullets as opposed to jacketed bullets. For example, in .338 Lapua, you can run a 1:9” or 1:10” with 300 grain SMKs, but a faster 1:8” with the solid 275 Lazer. The danger of pushing a jacked bullet too fast through a super-fast twist barrel is it may strip the jacket and the bullet may come apart.
This project .338 Lapua Magnum, built on a Stiller’s TAC338 action, will have a Bartlein 1:9″ twist barrel to optimize the Sierra 300 SMKs. But will also run tests with Cutting Edge .275 Lazers for comparison and ELR shooting.
Another reason for fast twist barrels and bullets in ELR shooting is retained RPM at extended ranges. RPM is one of the components of bullet stability so it makes sense that if the bullet starts out at a higher spin rate, it will retain more RPM as it passes from super-sonic into trans-sonic and subsonic. Thus the reason that solid bullets such as Cutting Edge dominate in ELR matches.
The final option, whatever barrel twist you may have on your factory or custom rifle, you can always re-barrel the rifle to the optimum twist for your chosen bullet and application. Serious competitive shooters consider match barrels as consumable, just like tires on your car. Just as you can change tires to best suit the conditions, you can change barrels to best suit your shooting needs. Similarly, when the barrel becomes worn and loses accuracy, just spend the $350 and get a new one. I have blue-printed actions and McMillan stocks that are 30 years old, but all it takes is a new match-grade barrel to have a new match-grade rifle.
.308 Winchester (left) .375 CheyTac (right) running Cutting Edge 352 MTACs and 400 Lazers