Anyone have any input for a new bbl for shooting at 100.
#of groves that handle the wind the best? 3,4,6etc..
Twist?
For 100yd BR but the guys over there only shoot at 50 and
thought some prone shooters would have some input.
Thanks
?'s 100yd shooters
Moderators: pilkguns, Marcus, m1963, David Levene, Spencer
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westerngriz
the "standard"twist is 1-16. but the other twists used are 1-16.5, 1-17, 1-17.5. Most people think that the slower the twist the more accurate the rifle. but at lower temps (65) the bullets out of the slower twists will not stablize. Essentialy the slow twists work great till it gets cool. then you might as well use a shotgun.
matt
matt
I have a Benchmark 2 groove 17 3/4 twist barrel on a 40 action I shoot benchrest with. I had the same concern as you until I got to talk to the gunbuilder that built it. He said to use round nose bullets. So I did and well..... I've won more matches half the matches I shot it. And that's one almost every week. Even in the winter with temps in the 30's. Using Wolf ME when everyone else was using Eley EPS.
I have to say in temps below about 60 degrees the EPS ammo will keyhole.
To be honest I have not shot it much at 100yds because as you say...our benchrest matches are at 50yds. The few times I have was solely to tune the rifle for the particular batch of ammo I was using. So I wasn't trying to shoot the X ring out. But I dont' think I'd be afraid of it. I'd love to find a good prone stock for it and give it a try. I know it would be a winner.
I have to say in temps below about 60 degrees the EPS ammo will keyhole.
To be honest I have not shot it much at 100yds because as you say...our benchrest matches are at 50yds. The few times I have was solely to tune the rifle for the particular batch of ammo I was using. So I wasn't trying to shoot the X ring out. But I dont' think I'd be afraid of it. I'd love to find a good prone stock for it and give it a try. I know it would be a winner.
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westerngriz
Slow twist..
Its hard to say that its more accurate. But it does offer some advantages.
Since I got it two fellow competitors have since bought one.
What I do think.... is it does better in the wind. The 2 groves has less drag, thus is less affected by the wind and requires less hold off to compensate.
When I got this rifle it was already 5yrs old and in the Benchrest game is on the old side as most don't keep barrels that long. It has had a fair amount of rounds shot through it and shows know signs of getting any worse. At least for me. Man how good was it when new??? I've put at least 3k rounds through it this year. I'm guessing it has close to 20k rounds through it. Gene Davis says they are good for at least 40K
I won another match with it today with a 249X7 in winds that were some of the most challenging I have ever shot in. Again with Wolf ME. If I remember correctly are rated at 1030 fps.
If and when it comes time to rebarrel. I'm going to buy another Benchmark Reverse Taper 2-groove 17 3/4 twist. I like it. When I find a good 40X prone stock I'm going to give it a try in prone. I know it will do well.
Since I got it two fellow competitors have since bought one.
What I do think.... is it does better in the wind. The 2 groves has less drag, thus is less affected by the wind and requires less hold off to compensate.
When I got this rifle it was already 5yrs old and in the Benchrest game is on the old side as most don't keep barrels that long. It has had a fair amount of rounds shot through it and shows know signs of getting any worse. At least for me. Man how good was it when new??? I've put at least 3k rounds through it this year. I'm guessing it has close to 20k rounds through it. Gene Davis says they are good for at least 40K
I won another match with it today with a 249X7 in winds that were some of the most challenging I have ever shot in. Again with Wolf ME. If I remember correctly are rated at 1030 fps.
If and when it comes time to rebarrel. I'm going to buy another Benchmark Reverse Taper 2-groove 17 3/4 twist. I like it. When I find a good 40X prone stock I'm going to give it a try in prone. I know it will do well.
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westerngriz
well good job. I won the sharpshooter class at perry. the rifle i used was an old Anschutz 2013 with i think the 26 inch barrel. While at perry I bought a 2013 barreled action with a 500mm barrel. just a few weeks ago i won the Regional metric prone match with that rifle. it seems to be shooting well.
My team mate got high woman and intermediate junior at perry and her barrel has well over 100,000 rounds through it. so i havent decided yet. I may play with different barrels till i find one that shoots the best in certain temps.
BTW do you experience dropped shots with the Wolf Match Extra? It seems to be the fatal flaw with SK Standard Plus. But I have never have had one because I weigh my ammo. I like the holes EPS makes though but IDK if it shoots better.
matt
My team mate got high woman and intermediate junior at perry and her barrel has well over 100,000 rounds through it. so i havent decided yet. I may play with different barrels till i find one that shoots the best in certain temps.
BTW do you experience dropped shots with the Wolf Match Extra? It seems to be the fatal flaw with SK Standard Plus. But I have never have had one because I weigh my ammo. I like the holes EPS makes though but IDK if it shoots better.
matt
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Guest
It seems to me that a lot of rimfire shooters regard ballistics and physics in general as some sort of unpredictable magical element in reality. They happen to be sciences that can explain a number of phenomenon - to include a couple of things you ask about...
For starters, the number of grooves will have a negligible effect on drag. Different numbers of grooves doesn't significantly effect drag because the ratio of land to groove area is preserved no matter how many grooves. The result is that there is negligible change in cross sectional area and thus, negligible change in drag.
Twist rate is an aspect that can net you a performance gain, albeit not a big one. As a bullet spins, any flaws in the center of gravity and symmetric cross section will cause dispersion. This is one of the big reasons you might get 7mm test groups at 50m, but 14mm groups at 100 yards would be impossible. By using a slower twist the effect of any imperfections are minimized. However, the difference between a 16 twist and a 17 (or 17.75) isn't anything to lose sleep over, especially considering the low muzzle velocity of .22s. As a side note, I'd like to point out that in button rifled barrels, which most smallbore barrels are, the twist rate of the finished barrel is notoriously unpredictable. I've seen barrels advertised as 16tw measure out anywhere between 15 and 17tw...
A huge factor, which I'm surprised no one has brought up, is ammo velocity. Once supersonic, aerodynamic drag is reduced with velocity, so its obvious that higher velocity is advantageous. However, our rimfire bullets are subsonic (hopefully). As a body approaches the sound barrier, it is subject to greatly increased drag. The practical implication is that you want to find ammo that shoots as slowly as possible (to a point).
A quick simulation in a ballistics program indicates that a .22 bullet traveling at 1080 FPS (muzzle velocity) has APPROXIMATELY 10% more wind drift at 100 yards than the same bullet at 1040 FPS.
In conclusion, if you have a barrel that shoots well, find a good SLOW lot of ammo that shoots lights out and go practice in the wind...
-Mark
For starters, the number of grooves will have a negligible effect on drag. Different numbers of grooves doesn't significantly effect drag because the ratio of land to groove area is preserved no matter how many grooves. The result is that there is negligible change in cross sectional area and thus, negligible change in drag.
Twist rate is an aspect that can net you a performance gain, albeit not a big one. As a bullet spins, any flaws in the center of gravity and symmetric cross section will cause dispersion. This is one of the big reasons you might get 7mm test groups at 50m, but 14mm groups at 100 yards would be impossible. By using a slower twist the effect of any imperfections are minimized. However, the difference between a 16 twist and a 17 (or 17.75) isn't anything to lose sleep over, especially considering the low muzzle velocity of .22s. As a side note, I'd like to point out that in button rifled barrels, which most smallbore barrels are, the twist rate of the finished barrel is notoriously unpredictable. I've seen barrels advertised as 16tw measure out anywhere between 15 and 17tw...
A huge factor, which I'm surprised no one has brought up, is ammo velocity. Once supersonic, aerodynamic drag is reduced with velocity, so its obvious that higher velocity is advantageous. However, our rimfire bullets are subsonic (hopefully). As a body approaches the sound barrier, it is subject to greatly increased drag. The practical implication is that you want to find ammo that shoots as slowly as possible (to a point).
A quick simulation in a ballistics program indicates that a .22 bullet traveling at 1080 FPS (muzzle velocity) has APPROXIMATELY 10% more wind drift at 100 yards than the same bullet at 1040 FPS.
In conclusion, if you have a barrel that shoots well, find a good SLOW lot of ammo that shoots lights out and go practice in the wind...
-Mark
occasional bullet drop???
I do, but for the cost difference for our fun matches every week. I can shoot a whole bunch of wolf for what Eley black or Red cost. As far as dropped shots go in smallbore benchrest. I can't say Eley doesn't drop. But I have seen plenty of other shooters who's Eley has.
I do have the range record too....Using Wolf ME
Too our guest that had the more scientific answers. I thought I covered most of the points you did without being too scientific. Yes it does all have to do with math. In the BR game it all does make a difference. And Yes you are correct about twist rate. It's hard to measrue, but yes it does matter. The BR game is an equipment race and all about splitting hairs. That is fun too if you have the money. That is why I have taken a liking to the prone matches. I get to focus and improve more on myself than the equipment. You can buy almost any factory Anschutz or similar and be competitive. But whichever game we play, we are all trying to squeeze out another point. We all try new and different things and learn with experience.
I do have the range record too....Using Wolf ME
Too our guest that had the more scientific answers. I thought I covered most of the points you did without being too scientific. Yes it does all have to do with math. In the BR game it all does make a difference. And Yes you are correct about twist rate. It's hard to measrue, but yes it does matter. The BR game is an equipment race and all about splitting hairs. That is fun too if you have the money. That is why I have taken a liking to the prone matches. I get to focus and improve more on myself than the equipment. You can buy almost any factory Anschutz or similar and be competitive. But whichever game we play, we are all trying to squeeze out another point. We all try new and different things and learn with experience.