RL 17 query

[Hillhunter]

thanks again , i have a lot to learn and read.

 

[Laurie]

I agree 100% with Steve Blair on all points. With an overall length of 1.353-inches as quoted by the bullet's designer Bryan Litz in his Applied Ballistics for Long Range Shooting books, a 1-12" twist rate gives the bullet a Stability Factor (Sg) of 1.36 under 'standard conditions' (59-deg F, 29.92 inches mercury pressure, 0% humidity). Raising air temperature to 80-deg takes the factor to above the usually recommended 1.4 Sg value, but this recommendation contains a fairly large safety factor anyway.

(In addition, Michael Courtney, a forum member, who has carried out extensive research on bullet stability has proved that stability calculators such as the Miller Rule used to calculate the 1.36 value above are overly 'pessimistic' in the case of HPBT match bullets such as the Juggernaut because the jacket and overall bullet length is greater than that of the internal lead core with an airspace in the tip.)

Add in another factor, that Bryan L used this bullet in US Palma and Fullbore sling shooting maybe three, four seasons back in his 1-13" twist Palma rifle and won just about everything in sight. He wasn't alone in this, many sling shooters discovering this bullet before the F/TR and Tactical people, although it was reported that many tried the bullet and subsequently switched to its 175gn little brother, not for ballistic performance issues, rather they found 185gn just above their recoil tolernace shooting off their elbows.

Bryan doesn't recommend 13-inch twist barrels for the bullet as stability is getting a bit marginal for all the year round use at this rate. Assuming he was knocking it out of a 30-inch barrel at ~2,800 fps, the Miller calculated Sg value is 1.20 at 59-deg F. This is decidedly marginal for long-range shooting as Michael Courtney in other published work showed that where the Sg value falls below 1.26, the effective BC of the bullet also takes a big hit - ie for some reason or other, the bullet incurs extra drag in flight.

So far as Re17 goes, I also agree with Steve. I found it inconsistent with the 185 in .308W even at 2,800 to 2,850 fps MV levels. It produced high MVs but was deficient in other areas. I reckon it really needs 210gn bullets and heavy loads to work properly in the cartridge, and even then our (GB) F/TR top league shooters who concentrate on 210-230gn bullets much prefer Viht N550 as they've found Re17 a bit unreliable in the cartridge.

 

[Hillhunter]

I agree 100% with Steve Blair on all points. With an overall length of 1.353-inches as quoted by the bullet's designer Bryan Litz in his Applied Ballistics for Long Range Shooting books, a 1-12" twist rate gives the bullet a Stability Factor (Sg) of 1.36 under 'standard conditions' (59-deg F, 29.92 inches mercury pressure, 0% humidity). Raising air temperature to 80-deg takes the factor to above the usually recommended 1.4 Sg value, but this recommendation contains a fairly large safety factor anyway.

(In addition, Michael Courtney, a forum member, who has carried out extensive research on bullet stability has proved that stability calculators such as the Miller Rule used to calculate the 1.36 value above are overly 'pessimistic' in the case of HPBT match bullets such as the Juggernaut because the jacket and overall bullet length is greater than that of the internal lead core with an airspace in the tip.)

Add in another factor, that Bryan L used this bullet in US Palma and Fullbore sling shooting maybe three, four seasons back in his 1-13" twist Palma rifle and won just about everything in sight. He wasn't alone in this, many sling shooters discovering this bullet before the F/TR and Tactical people, although it was reported that many tried the bullet and subsequently switched to its 175gn little brother, not for ballistic performance issues, rather they found 185gn just above their recoil tolernace shooting off their elbows.

Bryan doesn't recommend 13-inch twist barrels for the bullet as stability is getting a bit marginal for all the year round use at this rate. Assuming he was knocking it out of a 30-inch barrel at ~2,800 fps, the Miller calculated Sg value is 1.20 at 59-deg F. This is decidedly marginal for long-range shooting as Michael Courtney in other published work showed that where the Sg value falls below 1.26, the effective BC of the bullet also takes a big hit - ie for some reason or other, the bullet incurs extra drag in flight.

So far as Re17 goes, I also agree with Steve. I found it inconsistent with the 185 in .308W even at 2,800 to 2,850 fps MV levels. It produced high MVs but was deficient in other areas. I reckon it really needs 210gn bullets and heavy loads to work properly in the cartridge, and even then our (GB) F/TR top league shooters who concentrate on 210-230gn bullets much prefer Viht N550 as they've found Re17 a bit unreliable in the cartridge.

Thanks Laurie, i will try to develop with the N 140 and scrap the RL