30br-30ppc.....30ppc-30br

[Pete Wass]

As I recall Randy

They are random and usually only one per target. I don't recall seeing more than one per target. I haven't taped any backers this year yet but for the past several years I have noticed them. I haven't taken note if they come from one particular rifle but it would be interesting to do that and I will try to remember to do it; chart it a bit. I don't see anything we can do about it but I find it interesting all the same.

 

[Pete Wass]

If it's not the paper

yes. at longer distances it is more noticable and it is not the paper doing the key holing.

Why don't the record targets have key Holes in them? I have never seen that but it is common to see it on backers. I can't imaging that 3 extra feet is going to cause the bullets to flip sideways.

 

[Al Nyhus]

Way before the 30 BRs, we messed with these Sg numbers via our HUNTER Rifles : that is, we PAID to have the barrels made - as slow as 1:20" - and tested them with varying bullet LENGTHS, but static weights! The math holds up well and mirrors the predicted outcome(s) for various twist rates/bullet LENGTHS. Barrel/bullet combinations producing less than 1.4 Sg will, in clam conditions, shoot, but will make life misirable in the wind!

Ronnie Long suggested using the BR case following a couple of seasons of messing with 30x47 HBR chamberings, which featured 1:18" twist barrels!

Randy has touched on a part of the 30BR history that many, if not most, are unaware of. The 'twist/bullet length' issue was worked out by Hunter rifle shooters and experimenters like Randy. Roy Oines shot a 1:20 with Randy's .925's back in 1999 at the old Mason City, Iowa range, for example. -Al

 

[Pete Wass]

As the old adage goes- - -

Randy has touched on a part of the 30BR history that many, if not most, are unaware of. The 'twist/bullet length' issue was worked out by Hunter rifle shooters and experimenters like Randy. Roy Oines shot a 1:20 with Randy's .925's back in 1999 at the old Mason City, Iowa range, for example. -Al

We are standing on the shoulders of - - -

 

[R. G. Robinett]

while helping change targets and tape backers, there's a lot of key Holes in the backers. Does that say we are running our bullets on the ragged edge of stability when target paper and cardboard backers will turn them sideways?

No, because Sg, at 1.4 or, greater is NOT at the "ragged edge" . . . further, as a bullet decelerates, Sg INCREASES - the further it goes, the MORE stable the bullet becomes! Only a very few bullet designs are subject to dynamic instability (Sd) issues: flat-base bullets feature extreme Sd!

Randy J. is onto most of the answer: at the old mason City, IA range, where the AVERAGE wind velocity (24/7/365) is 18 MPH, at 200 Yd. and a healthy N/NW wind, individual bullet holes always displayed the 'nose-up' and into the wind attitude (off-center meplat 'punch-out') - even on the target! Also, have you ever worked the pits or, while shooting alone, heard the IMPACT of the bullets striking the target - when at the range alone, I frequently hear this . . the sound of a second impact means the group is wrecked! Especially where the bench and target do not provide a perpendicular target angle, I have seen bullets 'key-holeing' following target impact - some ranges make for less than head-on shooting. RG