Lothar Walther vs. Smooth Twist

[BTDT]

I cannot see how however a truely accurate rifled barrel can be bettered by one, equalled maybe.

I have tested an air rifle fitted with a SmoothTwist barrel. As far as I could tell given the conditions, the accuracy was a match for any rifled barrel I've used, but there were two differences.

The SmoothTwist barrel gave a small but nonetheless welcome improvement in measured ballistic coefficient.

The SmoothTwist barrel achieved excellent accuracy with every quality round head pellet I tried with it. It didn't magically increase the accurate range of hollow point or pointed pellets, but round head JSBs, H&N, RWS, Defiant and 1980s Wasp all performed well, with no barrel cleaning in between changing pellets.

As to whether the barrel could be more accurate than a top lapped rifled barrel, I don't know, but Ben reported tighter groups at 1050 fps than at 12 ft. lbs. (in .177") which Mike Wright believes is due to the twist rate of the barrel we tested. With a slower twist rate, sub-12 ft. lb. accuracy could be even better.

[simmmo]

I have tested an air rifle fitted with a SmoothTwist barrel. As far as I could tell given the conditions, the accuracy was a match for any rifled barrel I've used, but there were two differences.

Please explain given the conditions?

The SmoothTwist barrel gave a small but nonetheless welcome improvement in measured ballistic coefficient.

How was this measured I take it that the pellet left the ST barrel at exactly the same velocity as the standard barrel and both pellets/group of pellets weighed individually exactly the same?

If outdoors there was no change in wind humidity etc. between testing each barrel.

The SmoothTwist barrel achieved excellent accuracy with every quality round head pellet I tried with it. It didn't magically increase the accurate range of hollow point or pointed pellets, but round head JSBs, H&N, RWS, Defiant and 1980s Wasp all performed well, with no barrel cleaning in between changing pellets.

What do you mean by excellent accuracy? Distances shot, group sizes conditions etc.

As to whether the barrel could be more accurate than a top lapped rifled barrel, I don't know, but Ben reported tighter groups at 1050 fps than at 12 ft. lbs. (in .177") which Mike Wright believes is due to the twist rate of the barrel we tested. With a slower twist rate, sub-12 ft. lb. accuracy could be even better.

Can't see why it shouldn't be as accurate just can't see how it can be better if at 25yds indoors you can get 5 shot groups a pellet won't go through because that is tight in any unit of measurement centre to centre.

When groups open it is often more to do with user input and poor gun management in regards to fill pressure etc. If the barrel is up to it.

Andy

[BTDT]

Please explain given the conditions?

I don't have access to an indoor range and live half way up a hill. Wind conditions ranged from a very light crossing headwind (enough to cause smoke to drift but not move leaves) to an estimated force 5-6. I shoot here almost every day of the year and am very familiar with the accuracy I can expect in various wind states.

How was this measured I take it that the pellet left the ST barrel at exactly the same velocity as the standard barrel and both pellets/group of pellets weighed individually exactly the same?

If outdoors there was no change in wind humidity etc. between testing each barrel.

My chrono is not accurate enough for absolute measurements, but OK for comparative, and is in a very sheltered spot. The velocities were close though not exact, I did not weigh the individual pellets and the conditions were constant. The difference was quite sufficient to convince me.

My friend Mike Wright tested the same rifle, with a better chrono and the same results - a slightly higher BC than his Rapid with every pellet he tested.

What do you mean by excellent accuracy? Distances shot, group sizes conditions etc.

The most outstanding group was 4.7mm c-t-c at 35 yards with 1980s Wasp (which was probably a fluke, despite being ten pellets), in light wind, in which other group sizes were Defiant 8.9mm, Bisley Superfield 8.2mm, Accupell 6.8mm. At 50 yards, with a 15-20 mph crossing headwind, RWS Superfield, Air Arms Field, H&N FTT all grouped at sub 0.75".
Mike tested with Mosquitos in a slight tail wind and had 8.4mm groups at 35 yards with the Elan and with his Rapid, 10.2MM with his Whiscombe FB (slow twist polygonal barrel) and 17.8mm from all three at 50 yards.

Can't see why it shouldn't be as accurate just can't see how it can be better if at 25yds indoors you can get 5 shot groups a pellet won't go through because that is tight in any unit of measurement centre to centre.

I agree entirely. A pellet can't go through a hole smaller than itself! If the SmoothTwist could be more accurate, it would only be apparent at longer range.

When groups open it is often more to do with user input and poor gun management in regards to fill pressure etc. If the barrel is up to it.

Andy

Nobody knows better than me that groups usually open up due to pilot error.

[Adam77K]

If these barrels deliver what the people in the know claim, then they will be the holy grail for FT shooters. There's not that much improvement available in pure group size from a good barrel and with good pellets. But if a barrel could deliver that level of accuracy, reduce the need to seek out specific batches of pellets, reduce the need to clean, and all that together with a potential improvement in wind performance from the better BC I can see the tubes (and rifles fitted with them) changing hands for considerable sums.

[BTDT]

If these barrels deliver what the people in the know claim, then they will be the holy grail for FT shooters. There's not that much improvement available in pure group size from a good barrel and with good pellets. But if a barrel could deliver that level of accuracy, reduce the need to seek out specific batches of pellets, reduce the need to clean, and all that together with a potential improvement in wind performance from the better BC I can see the tubes (and rifles fitted with them) changing hands for considerable sums.

To pick up on the barrel cleaning, I forgot to mention in my reply to Simmmo that I shot a total of 14 different pellets through the Elan and did not clean the barrel once.

The potential lessening of susceptibility to wind drift through improved BC did not escape our attention. My first tests were in a following force 5-6 crossing at roughly 30 degrees and veering. At 50 yards: Mosquito 35mmx34mm. Bisley LRG 37mmx34mm. Superdome 36mmx22mm. The Mosquito group was only 8 pellets because it took me nine shots to get on target, the others 17 pellets each. Three very different pellets, three very similar groups in atrocious conditions.

[baz]

In rimfire tests the ST barrel has matched the accuracy of target Anschutz barrels, you really cant get much better than that, to measure any difference would have taken really precise measuring, one (tiny) hole groups are good enough for me

[simmmo]

In rimfire tests the ST barrel has matched the accuracy of target Anschutz barrels, you really cant get much better than that, to measure any difference would have taken really precise measuring, one (tiny) hole groups are good enough for me

True Baz you can't but then again like you said you can't get any better my Match 54 was made in 1968 and still shoots 5 shot single hole groups the bullet will not pass through at 25yds. Maybe this just shows quality control and modern machine methods are no better and possibly worse than they used to be. Oh the 54 is bedded in a Mr Moon stock though.

Andy