284Win vs 280 Rem/ 7x64

S

supersonic

Guest
Hello to everyone.

I am new here and I want to apologize for my pure english.I live in Europe.I would be pleased if you could give me an advice.
I shoot long range matches in eastern Europe. I use the 6,5x55.
I would like to move to the 7mm cartridge, to be able to better compete against bigger calibers like 300WM. I do want to avoid really big 7mm cases like 7 SAUM or bigger, or Ackley versions. That is why I want to use 7x64(I have dies for it,since I reload for my friend)-7x64 is the almost twin to 280 Rem or I think also about 284Win. All have almost the same case capacity, but longer and narrower cases(7x64) would give me the advantage of magazine capacity 5cases inside instead of just 4 in my hybrid rifle. But 6,5 x55 which I own seems hard to me to achieve low velocity spread. Would velocity spread be lower with 284win compare to 280Rem/7x64 provided the same, let say quality cases would be used,but no neck turning..Would there be an advantage regarding the velocity spread for 284win over 7x64/280Rem because of itś fatter and shorter case..?? If yeas,how big would be the diference between the two? One more question-did anybody of you measured somehow the BC of the new 7mm 180gr Lapua Scenar bullet?
Thanks a lot for your help.
Petr
 
Petr,

I cannot address all of your questions directly.

As no one else is posting, I do have a few thoughts for you that might get you pointed in the right direction or, at least, prompt others to jump in.

1. Without knowing what form of match you are shooting in, it is hard to discuss the magazine capacity question. You might address it by modifying your rifle to use after-market magazines. To do so, you would likely have to change to different bottom metal.

2. Achieving the low ES that the long-range benchrest community gets is a very tedious process. Extensive case preparation/maintenance, sorting bullets by bearing surface, using analytical balances that can measure single granules of powder, etc. If you have explored this and are still not getting satisfactory ES, I suggest that you might contact Greg Walley at Kelbly rifles and ask him if he feels the wildcat cartridge that he builds from the 6.5x55 aids in attaining lower ES.

3. The 284 Winchester or the 284 Shehane that is based on it are fine 7mm rounds that many people on this side of the pond shoot in F-Open and other long-range games. They have the advantage over the 7 WSM and 7 SAUM of being able to neck up 6.5x284 Lapua brass. Dies and information are readily available. Either is a winning combination. You might check out http://www.accurateshooter.com/cartridge-guides/7mm/ and http://bulletin.accurateshooter.com/2013/10/how-to-win-at-1000-yards-ibs-national-champ-tells-all/ for more info.

4. I have no information about the ballistic coefficient of the new 7mm/180gr Scenar. I don't know of anyone shooting it. Most of the people that I know shooting a 7mm are shooting the 180gr Berger Hybrid or custom bullets. But, the bullet looks interesting. I'm going to try to find some to try.

Best regards,

Greg Jennings
 
SGJennings said:
Petr,

I cannot address all of your questions directly.

As no one else is posting, I do have a few thoughts for you that might get you pointed in the right direction or, at least, prompt others to jump in.

1. Without knowing what form of match you are shooting in, it is hard to discuss the magazine capacity question. You might address it by modifying your rifle to use after-market magazines. To do so, you would likely have to change to different bottom metal.

2. Achieving the low ES that the long-range benchrest community gets is a very tedious process. Extensive case preparation/maintenance, sorting bullets by bearing surface, using analytical balances that can measure single granules of powder, etc. If you have explored this and are still not getting satisfactory ES, I suggest that you might contact Greg Walley at Kelbly rifles and ask him if he feels the wildcat cartridge that he builds from the 6.5x55 aids in attaining lower ES.

3. The 284 Winchester or the 284 Shehane that is based on it are fine 7mm rounds that many people on this side of the pond shoot in F-Open and other long-range games. They have the advantage over the 7 WSM and 7 SAUM of being able to neck up 6.5x284 Lapua brass. Dies and information are readily available. Either is a winning combination. You might check out http://www.accurateshooter.com/cartridge-guides/7mm/ and http://bulletin.accurateshooter.com/2013/10/how-to-win-at-1000-yards-ibs-national-champ-tells-all/ for more info.

4. I have no information about the ballistic coefficient of the new 7mm/180gr Scenar. I don't know of anyone shooting it. Most of the people that I know shooting a 7mm are shooting the 180gr Berger Hybrid or custom bullets. But, the bullet looks interesting. I'm going to try to find some to try.

Best regards,

Greg Jennings
Click to expand...
Petr to
Mr. Greg Jennings,

I really thank you very much for your help. I cannot probably alter magazine capacity on my rifle. 7x64 is my candidate,but I am not decided yeat. To get a good brass for it,I would have to get Norma-they produce 7x64 brass. I am used to Lapua(for my 6,5x55). Norma can be too soft-that is what I have heard. Regarding velocity spread..to be honest,I only have quality scale for powder and I weigh-sort brass and I am getting and using one lot of quality bullets like Berger and Lapua. I do not plan mutch more than that. But from what I see and hear around here in my country,it seems that a lot of other shooters here are not doing more than me,but they still are having much smaller velocity spread when using .308 Win and 6mm Norma BR.
I thought it was just caused by cartidge designe.
When I tune my loads,sometimes I notised very low velocity spread,but accuracy was poor.
Unfortunately,when I test my loads at 100m or 300m and accuracy is much better,than velocity spread get worse... That is why I was pleased to see what you sent to me-the link to SUPERTUNER. Seems it could be solution... I would rather get sumething like that, but without muzzlebreak and something what would prolong the barrel as little as possible...
I was trying to find some youtube video to see it working without muzzlebreak ,but I found nothing so far. Maybe I could improve my results if I was able to get my smallest groups to be shot with my loads showing the lowest velocity spread when using some kind of supertuner for that..and that may even postpone my decision to change caliber. Well it would depend on my ability to get that thing into my hands..
Anyway-it was very interesting to get your message here. I wish you all the best and thank you very much! Petr
 
Petr,

I have a friend who is a PhD radio chemist. He works. He does not teach. He's very accustomed to taking and recording precise measurements. He recently did a box of premium 30 caliber match bullets by bearing surface with my Mark King/John Buhay (see http://www.markkingrifles.com/pages/pricing.php). The "bucket" to get 2/3rds of the bullets into one group was .010 inches wide. In otherwords, 2/3rds of the bullets' bearing surface varied by 0.010" 1/3rd were worse than that. Ouch! So, I am now a believer in sorting bullets for long range.

Another thing that some top shooters do is anneal every firing. Tedious, but it contributes to consistent neck tension.

My friend Mike Ezell, http://www.ezellcustomrifles.com/ , makes a very fine tuner at a very good price. You might investigate it. I know that it's not on the site yet. Go to http://www.6mmbr.com/ go into the forums and do a search for keyword "tuners" with user "gunsandgunsmithing". His thread should be the very first. Sorry to not provide the link, my work network has 6mmbr blocked and the email that where I sent it to myself hasn't arrived.

In honesty, though I do not have data to back it up, I believe that more efficient cases, especially when filled to near 100% capacity, deliver lower ES. If you are sticking to the 7x64, I would try to find a powder that gives the velocity that you want and that fills the case as close to 100% as possible. A little empty space or a bit of a compressed charge wouldn't bother me, but a lot of empty case would.

With all that said, the largest thing that I caution you about is that it looks like you are blazing your own trail. The cartridge might be a loser for any number of reasons. Time and barrel life are precious. I'm adventurous, even to the point of crafting my own wildcat. But, there is NO WAY that I'd go out completely on a limb with a cartridge. It would have to have a record of being a winner with data on winning loads available before I would take it up.
 
case capacity - you are required to load and shoot individual shots in all the matches that I have attended, so magazine capacity is not a question.

I run a modified version of the 280 Ackley (mine is a true 30-06 Ackley - Lapua brass - necked down to 7mm). armed with Berger 180s, it stays with virtually everything on the line when it come to holding into the wind. Supposedly someone running the new 230 Berger Hybrid in a 300WSM or 300WM will hold inside me - I have not yet had the occasion to see that at our fairly small local matches. I used to shoot the true 7WSM w/ Berger 180s @ 3,020 fps. Both the 7/30-06 Ackley and 7WSM are capable of running tight ES and SD (meaning ES of 15 or less and SD of 9 or lower). When shooting 1,000 yard F-Class you truly need that tight waterline - meaning the ability to confine your group's vertical to inside the X ring or very close to it. I do all of my finalize load testing at either 400 meters or 525 meters. If it shoots at 400/525 meters it will shoot at 1,000 yards - at least in my experience. I would prefer to do load testing @ 1,000 yards, but that is not possible under normal circumstances given how our range is set up.

I anneal after 2 firings, and length sort my projectiles (base to ogive) into 1/1000" lots using a digital caliper and shoot them together from shortest to longest in lots as I chase the throat. the other aspects of load development and tight ES and SD are too much for this short discussion.

Jeffvn
 
Petr, find a GOOD electronic scale, one that will measure to the individual kernel of powder. Reload to the KERNEL of powder..... do not believe "tenths of a grain."

Reload so that ONE PIECE of powder shows on your scale and your reloads are within one kernel of powder.

Report back on ES

al
 
I'd put more on the table:

1. Consistent powder charge to or near the kernel of powder. You can get pretty close with a good beam balance.
2. Consistent neck tension / seating effort. Anneal. Polish the inside of the neck. Sort by seating force.
3. Consistent bullet bearing surface length. Bearing surface is best. Base to ogive if you can't do bearing surface.
4. Consistent case volume. Not weight. *Volume*. I use 99% alcohol for volume.
5. Consistent ignition. Proper and consistent primer indent. Consistent flash hole.

BTW, Petr, I ordered a couple of boxes of the 7mm 180 gr Scenar-L bullets. They are back ordered. When they arrive, I'll give you a report on them.
 
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