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Long Range Hunting & Shooting
Hunting with the Lapua Scenar bullet (muzzle velocity above 3000fps)
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<blockquote data-quote="RockyMtnMT" data-source="post: 1194094" data-attributes="member: 7999"><p>I would say that fragments tend to move out ward from the direction of bullet travel. What I have seen happen with the stability is like a top. As long as it is spinning fast enough it can over come the heaviness of the larger part wanting to pass the point or tip over. What we found is that when bullets were tested for impact at low velocity with reduced loads is the stability went down with as the velocity was reduced. We figured out what was going on when testing a .243 bullet at 1800fps muzzle velocity from a ten twist barrel. This slow vel reduced the stability factor down to about 1.3 sg, if I remember correctly. Technically enough stability for good accuracy. I knew this was happening to the stability before we started testing the various bullets, but did not think it would matter since we were shooting into media at about 10 yards. We were trying to find the velocity floor for the little bullet but could not get it any faster with the reduced load powder in the 243 win. We had a project barreled action sitting there waiting for a stock to come in that is chambered in 6-284 lapua. Little bigger case so we thought we could get a bit more velocity out of it. We loaded it with the first test load and it ran the same muzzle vel as the 243 1800 fps. So we went to dig it out of the media before we loaded another a bit hotter. Low and behold the bullet functioned perfectly at the same vel as before. Only difference was the second rifle had a 7" twist so the low vel sg was still very high well above 1.5 sg. That is when is dawned on us that the faster spinning bullet could maintain orientation on impact and keep the intended path point forward and allow the hollow point design to do as intended.</p><p></p><p>I am not sure if I can answer the COP vs COG question with good intelligence. I can say that the secant ogive with tend to give better bc than the tangent ogive but be more difficult to tune. This may be due to the amount of twist with the ogive type, but I can not say that for sure. We have and will probably stay with the tangent ogive design that we have for the fact that it has been so easy to tune. I will take accuracy over bc all day.</p><p></p><p>I am sure that you have seen bullets recovered that the nose is a bit bent like a banana. This from the lack of stability and as the base of the bullet overcomes the point in orientation the weakness of the thinner tip will bend. This is what can cause a bullet to head in a different direction than original. Often tumbling bullets will stay on the correct path and do heavy damage appearing to be great bullet performance. Only if you recover that bullet can you tell if it opened properly or tumbled though and out of the animal.</p><p></p><p>The best explanation I can give with my limited science back ground. I learn all my stuff by doing it wrong.</p><p></p><p>Steve</p></blockquote><p></p>
[QUOTE="RockyMtnMT, post: 1194094, member: 7999"] I would say that fragments tend to move out ward from the direction of bullet travel. What I have seen happen with the stability is like a top. As long as it is spinning fast enough it can over come the heaviness of the larger part wanting to pass the point or tip over. What we found is that when bullets were tested for impact at low velocity with reduced loads is the stability went down with as the velocity was reduced. We figured out what was going on when testing a .243 bullet at 1800fps muzzle velocity from a ten twist barrel. This slow vel reduced the stability factor down to about 1.3 sg, if I remember correctly. Technically enough stability for good accuracy. I knew this was happening to the stability before we started testing the various bullets, but did not think it would matter since we were shooting into media at about 10 yards. We were trying to find the velocity floor for the little bullet but could not get it any faster with the reduced load powder in the 243 win. We had a project barreled action sitting there waiting for a stock to come in that is chambered in 6-284 lapua. Little bigger case so we thought we could get a bit more velocity out of it. We loaded it with the first test load and it ran the same muzzle vel as the 243 1800 fps. So we went to dig it out of the media before we loaded another a bit hotter. Low and behold the bullet functioned perfectly at the same vel as before. Only difference was the second rifle had a 7" twist so the low vel sg was still very high well above 1.5 sg. That is when is dawned on us that the faster spinning bullet could maintain orientation on impact and keep the intended path point forward and allow the hollow point design to do as intended. I am not sure if I can answer the COP vs COG question with good intelligence. I can say that the secant ogive with tend to give better bc than the tangent ogive but be more difficult to tune. This may be due to the amount of twist with the ogive type, but I can not say that for sure. We have and will probably stay with the tangent ogive design that we have for the fact that it has been so easy to tune. I will take accuracy over bc all day. I am sure that you have seen bullets recovered that the nose is a bit bent like a banana. This from the lack of stability and as the base of the bullet overcomes the point in orientation the weakness of the thinner tip will bend. This is what can cause a bullet to head in a different direction than original. Often tumbling bullets will stay on the correct path and do heavy damage appearing to be great bullet performance. Only if you recover that bullet can you tell if it opened properly or tumbled though and out of the animal. The best explanation I can give with my limited science back ground. I learn all my stuff by doing it wrong. Steve [/QUOTE]
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Hunting with the Lapua Scenar bullet (muzzle velocity above 3000fps)
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