270 and Long Distance

[thomae]

Guys,
This is a quiet reminder that you are way off topic.

Mach2's question appears to have been answered well some posts ago and since then, the discussion has turned to an extremely detailed discussion of the finer points of external ballistics.

I am not against this discussion, but may I gently suggest that if you wish to continue your discussion, you start an appropriate new thread?

I didn't stay at a Holiday Inn express, and I'm not a moderator (or even a replacement referee), but I thought I'd say something before you get jumped on by one.

Thanks

[M.O.A.]

.Helotaxi said(quote) Two bullets of the same BC fired at the same velocity will fly exactly the same even if one weighs 200gn and the other 50.(end quote)

Mach2 replies:
Im trying to follow you guys. So here goes. If you drop a 5lb cannon ball from 5 feet it will land at the same time as a 10 lb cannon ball is fired from a cannon 5 feet high no matter what amount of powder used. Assuming the cannon is aimed parallel to the ground. Is that correct? I think I heard that in physics. Unfortunantly I was hungover in that class.
This is not right it has to be the same weight as 10lbs and 10lbs

[Mach2]

I started this thread and I enjoyed what was discussed. I learned more in this thread than all the other threads Ive ever read in this entire blog. I used to buy rifles because they had beautiful wood stocks. The next rifle I buy will be due to qualities you cant see by looking at the gun.

[FUBAR]

I understood his example, here is a link: http://hyperphysics.phy-astr.gsu.edu/hbase/grav.html

Yes it's time to close this thread.

[Tom Brush]

I did not read all of the posts but the ones I did reminded me of a story I told before but It sticks in my mind when talking long range. Several years ago I was on a western trip. We covered a number of states and were coming home thru Wyoming during Antelope season. I saw a large herd of Antelope and stopped along the road to film them. I filmed for several minutes and then heard a shot. I looked all around but did not see a hunter. I did see a doe get hit by the bullet. She just stood there obviously sick. Soon another shot rang out and the doe dropped. I looked around for the hunter and soon he stood up in the sage. He walked to the doe and went back the way he came. I remembered a car back down the road so I turned around and drove back to it. When I got there the hunter was there. He forgot his knife and went back to get it. I got out and talked to him for a while.

He was a local hunter. I asked how far the shot was and he said 732 yds. He said that this was his last tag. He shot his first doe the week before also over 700 yds. I looked at his rifle and it was a .280 Remington with a large target scope. His rifle was a 700 ADL (WalMart special! I told him that the shot was amazing with a sporter rifle. He looked at me and said "this isn't my long range rifle. My long range rifle is the same but in .270".

[Tom Brush]

I did not read all of the posts but the ones I did reminded me of a story I told before but It sticks in my mind when talking long range. Several years ago I was on a western trip. We covered a number of states and were coming home thru Wyoming during Antelope season. I saw a large herd of Antelope and stopped along the road to film them. I filmed for several minutes and then heard a shot. I looked all around but did not see a hunter. I did see a doe get hit by the bullet. She just stood there obviously sick. Soon another shot rang out and the doe dropped. I looked around for the hunter and soon he stood up in the sage. He walked to the doe and went back the way he came. I remembered a car back down the road so I turned around and drove back to it. When I got there the hunter was there. He forgot his knife and went back to get it. I got out and talked to him for a while.

He was a local hunter. I asked how far the shot was and he said 732 yds. He said that this was his last tag. He shot his first doe the week before also over 700 yds. I looked at his rifle and it was a .280 Remington with a large target scope. His rifle was a 700 ADL (WalMart special! I told him that the shot was amazing with a sporter rifle. He looked at me and said "this isn't my long range rifle. My long range rifle is the same but in .270".

[Tom Brush]

I did not read all of the posts but the ones I did reminded me of a story I told before but It sticks in my mind when talking long range. Several years ago I was on a western trip. We covered a number of states and were coming home thru Wyoming during Antelope season. I saw a large herd of Antelope and stopped along the road to film them. I filmed for several minutes and then heard a shot. I looked all around but did not see a hunter. I did see a doe get hit by the bullet. She just stood there obviously sick. Soon another shot rang out and the doe dropped. I looked around for the hunter and soon he stood up in the sage. He walked to the doe and went back the way he came. I remembered a car back down the road so I turned around and drove back to it. When I got there the hunter was there. He forgot his knife and went back to get it. I got out and talked to him for a while.

He was a local hunter. I asked how far the shot was and he said 732 yds. He said that this was his last tag. He shot his first doe the week before also over 700 yds. I looked at his rifle and it was a .280 Remington with a large target scope. His rifle was a 700 ADL (WalMart special! I told him that the shot was amazing with a sporter rifle. He looked at me and said "this isn't my long range rifle. My long range rifle is the same but in .270".

[M.O.A.]

Well the 280 is a great round with great bullets ;-) and might be my next gun but I wounder why savage doesn't have a rifle ni it ??????

[Jamie]

Well, the reason I started this thread about the 270Win is that I already had a one and wondered if it was worth spending money on a 260Rem since there is only .010 difference in caliber. I wondered if I could achieve the same thing with a 270 as I could with a 260. It seems such a tiny difference
(.010)The amswer seems to be that I could or nearly could achieve the same result if I studied and worked at it. But at long distance I may achieve what I want easier and sooner with a 260 from the standpoint of a novice tying to get somewhere..



That would be an accurate statment. You could or come close enough for practical purposes with the .270 Win but it would most likely be easier with the .260 Rem. The .270 has a very limited choice of long range bullets though and that will make it tougher. Besides, there does seem to be something special about the 6.5s. I do think more shooting time and less computer time would benefit a lot of people.

[helotaxi]

Almost no one does. Browning and Winchester do right now. Remington comes and goes. Nosler chambers the Ackley Improved version. Lots of barrel makers chamber for it though and with a Savage, that's all you need ;)

[rusty815]

Just thought everyone here would like to know, that among other things, Nosler is releasing a new Accubond long range bullet for the 270 with a BC of .625 according to them:

http://www.noslerreloading.com/phpBB2/viewtopic.php?f=4&t=21141&sid=39598f954e9d0003cb98d85a30a6b97f

Should make the 270 competitive at long range, if those numbers are true that is.

[helotaxi]

Nosler is known to use the highest velocity range BC as their advertised number. The real number decreases with velocity and the average will work out in the .60 range most likely. I wouldn't trust it until is was verified and certainly wouldn't attempt a long shot based solely on that advertised number without some real world dope.

Regardless, I'm looking forward to getting ahold of some of them the .270 and 7mm.

[thomae]

Anyone shoot the Woodleigh 180 grain protected point? I'd be interested in how that performs on game.

[rusty815]

Nosler is known to use the highest velocity range BC as their advertised number. The real number decreases with velocity and the average will work out in the .60 range most likely. I wouldn't trust it until is was verified and certainly wouldn't attempt a long shot based solely on that advertised number without some real world dope.

Regardless, I'm looking forward to getting ahold of some of them the .270 and 7mm.

Except they also listed the G7 BC, which isn't velocity dependent and is still a very high number, but I do know that they have been known to really inflate their BC numbers. The fact that they list a G7 BC to me shows that there might be some truth in the numbers their claiming, but like most other people, I will remain skeptical until the real world numbers come out.

[FUBAR]

G7 still uses velocity--Drag Functions simplified Drag Coefficients...

G7 is for a particular projectile shape, we want to use the drag function whose BC changes the least over a range of specified/usable velocities

[rusty815]

Taken for Longrangehunting.com's article about Berger moving to the G7 BC model:

"the BC of a modern long range bullet that’s referenced to the G7 standard is constant for all velocities! In other words, a trajectory that’s calculated with a ‘G7 BC’ doesn’t suffer from the same velocity dependence problems and inaccuracies as calculations that are made with a G1 BC."

[helotaxi]

Yep. The G7 model essentially accounts for the variability of the drag coefficient as part of the model. The G1 model does not. The G7 model also better models the drag profile of a long profile boat-tailed bullet compared to the G1 model.

I'd forgotten that the new Noslers had the G7 listed. I'm curious how they derived them. The BC can be derived by computer modeling or measured. Most bullet makers derive their BCs and they end up inflated, at least slightly. Sierra measures theirs. Berger has measured values for some of theirs as well.

[FUBAR]

Taken for Longrangehunting.com's article about Berger moving to the G7 BC model:

"the BC of a modern long range bullet that’s referenced to the G7 standard is constant for all velocities! In other words, a trajectory that’s calculated with a ‘G7 BC’ doesn’t suffer from the same velocity dependence problems and inaccuracies as calculations that are made with a G1 BC."

Someone left off the word relatively in front of constant above... Here is a short condensed version of this topic on the JBM website: http://www.jbmballistics.com/ballistics/topics/bcs.shtml

I only took issue with the statement that "G7 was not velocity dependent". ALL G drag functions are velocity dependent.

I completely agree that for this bullet selection the G7 drag function model is the better choice...

G7 BCs, for certain bullet types, are more constant over the useable velocity spectrum for the particular type, but so is G1 for certain types of bullets.

Note: roughly speaking we are talking about supersonic Longrange shooting, where the bullet maintains supersonic-transonic velocities.

There are Longrange shooters that for well over 100 years have been lobbing heavy low BC bullets into a target aroun 1/4 mile away :cool:

However their bullets quickly go subsonic, and at subsonic the design parameters change, here is an excerpt:

"Subsonic (below about 1090 fps depending on air density) bullets have their BC more affected by the shape of the base than the nose. A very blunt bullet can have its BC improved by nearly 40% by changing from a flat base to a rebated boattail shape...."