7BR
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- Start date
geo.ulrich
Active member
Really it has been used before...
geo.ulrich
Active member
Actually I do make 100 gr 7's only .024 smaller in dia. and 3250 for velocity works well
Fuj
New member
Your killing me George !!!.....LOL The 100 grain bullet in the BR will do well.
I decided to go to a much bigger boiler room, and still experiment with the
lightest bullets I can get my hands on. Currently it's the 100 gr FB Sierra
Varmint. I have it shooting in the ones, and have not had time to do the
seating depth tests yet.......Yeah it's not mainstream, but no one ever accused
me of being mainstream. Been shooting and experimenting the smaller 7's for
years.
George, if you have'nt yet, check out my 7.2 Greedmore thread in the large
caliber section on A.S.......Still working on my concept of a bullet press for a
different need. I should have done this years ago, but that thread you and Al
have going, drove me over the edge.
I decided to go to a much bigger boiler room, and still experiment with the
lightest bullets I can get my hands on. Currently it's the 100 gr FB Sierra
Varmint. I have it shooting in the ones, and have not had time to do the
seating depth tests yet.......Yeah it's not mainstream, but no one ever accused
me of being mainstream. Been shooting and experimenting the smaller 7's for
years.
George, if you have'nt yet, check out my 7.2 Greedmore thread in the large
caliber section on A.S.......Still working on my concept of a bullet press for a
different need. I should have done this years ago, but that thread you and Al
have going, drove me over the edge.
Pete Wass
Well-known member
An old friend used to shoot a 7 mm HBR rifle. Said it shot great but he had trouble getting good 7mm jackets so he never got back to it. Potentially it might be a better 300 yd rifle but like anything else, one must have good bullets. Generally speaking, 7 mm rifles are known for their accuracy and wind bucking. Plus, it would be fun to have something different. Something different often turns into an impossible situation or not what we think it will be. Been there, done that and still have a few tee shits.
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Pete Wass
Well-known member
Ask Randy Robinette.
R.G. Robinett
"That'll never work."
"If 7mm would work, everyone would be using them . . . " - a bench-rest mentality made up quote. 
The late Gary Long messed with the .284 bullets some, as I believe George Ulrich and two lesser know individuals have done: with suitable BR quality bullets, there is ZERO reason that a 7BR would not be competitive - THE issue has always been the availability of suitable jackets - especially, "short enough" to make, say 90-100 Gr. weight bullets.
Then, you remain, from the status quo perspective - especially for group shooting - faced with "excessive" recoil, similar to a thirty Cal., while, for score shooting, giving up radius and still coping with the recoil! From my odd-ball perspective, It's PSYCO- LOGIC
. . . one can either "shoot", or, not. To repeat, THE issue has always been the unreliable jacket availability. The individuals I know who tried and made excellent 7mm bullets found the jacket issue & the lack of noticeable advantage, not worth the expense and effort.
Inside of 300 yards, BC isn't worth consideration - you aren't that good. Lets compare an existing .30 Cal. 118 Gr. bullet with G1 BC .330, & 3050 FPS MV, to an imaginary .370 BC (it won't be that good) 7mm bullet of about 95 Gr., MV 3100 FPS. At 200 Yd., a constant vector/velocity 1MPH wind will drag the thirty Ca. bullet about 0.36", while the 7mm will suffer "only" 0.31": 0.050" less, or, the equivalent of 0.14 MPH variation of wind velocity . . . nobody can dope anywhere near that fraction! EDGES work only for the WINNER, while everyone else whines . . . Before a PPC toter gets all upset, in the same scenario, the average 68 Gr. 6mm bullet featuring a generous G1 BC of 0.28, at 3400 FPS MV, will be dragged 0.37".
But, I'm drifting - score some dies, & jackets, make some good BR quality light weight bullets, and a 7mm will give up nothing, nor will it provide any useful advantage - it would fall into the category of, "I just want to do it". Before you order your dies, order a supply of jackets . . . or, your dies may be useless . . .RG
The late Gary Long messed with the .284 bullets some, as I believe George Ulrich and two lesser know individuals have done: with suitable BR quality bullets, there is ZERO reason that a 7BR would not be competitive - THE issue has always been the availability of suitable jackets - especially, "short enough" to make, say 90-100 Gr. weight bullets.
Then, you remain, from the status quo perspective - especially for group shooting - faced with "excessive" recoil, similar to a thirty Cal., while, for score shooting, giving up radius and still coping with the recoil! From my odd-ball perspective, It's PSYCO- LOGIC
. . . one can either "shoot", or, not.
To repeat, THE issue has always been the unreliable jacket availability. The individuals I know who tried and made excellent 7mm bullets found the jacket issue & the lack of noticeable advantage, not worth the expense and effort.Inside of 300 yards, BC isn't worth consideration - you aren't that good.
Lets compare an existing .30 Cal. 118 Gr. bullet with G1 BC .330, & 3050 FPS MV, to an imaginary .370 BC (it won't be that good) 7mm bullet of about 95 Gr., MV 3100 FPS. At 200 Yd., a constant vector/velocity 1MPH wind will drag the thirty Ca. bullet about 0.36", while the 7mm will suffer "only" 0.31": 0.050" less, or, the equivalent of 0.14 MPH variation of wind velocity . . . nobody can dope anywhere near that fraction! EDGES work only for the WINNER, while everyone else whines . . . Before a PPC toter gets all upset, in the same scenario, the average 68 Gr. 6mm bullet featuring a generous G1 BC of 0.28, at 3400 FPS MV, will be dragged 0.37".But, I'm drifting - score some dies, & jackets, make some good BR quality light weight bullets, and a 7mm will give up nothing, nor will it provide any useful advantage - it would fall into the category of, "I just want to do it". Before you order your dies, order a supply of jackets . . . or, your dies may be useless . . .
RG
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geo.ulrich
Active member
Randy, You correct unless you want to pinch and draw .925s down I was lucky and got sierra to run a bunch. now they are gone and need to go through more work. You are a little light on your velocity for the 7mm.."If 7mm would work, everyone would be using them . . . " - a bench-rest mentality made up quote.
The late Gary Long messed with the .284 bullets some, as I believe George Ulrich and two lesser know individuals have done: with suitable BR quality bullets, there is ZERO reason that a 7BR would not be competitive - THE issue has always been the availability of suitable jackets - especially, "short enough" to make, say 90-100 Gr. weight bullets.
Then, you remain, from the status quo perspective - especially for group shooting - faced with "excessive" recoil, similar to a thirty Cal., while, for score shooting, giving up radius and still coping with the recoil! From my odd-ball perspective, It's PSYCO- LOGIC
. . . one can either "shoot", or, not.
Inside of 300 yards, BC isn't worth consideration - you aren't that good.
But, I'm drifting - score some dies, & jackets, make some good BR quality light weight bullets, and a 7mm will give up nothing, nor will it provide any useful advantage - it would fall into the category of, "I just want to do it". Before you order your dies, order a supply of jackets . . . or, your dies may be useless . . .
R.G. Robinett
"That'll never work."
George got me all wound-up with the velocity thing, so, I did a little fiddling on the Tioga Bullet Design program - to see what the real-world BC, for a 100 Gr. 7mm/.284 HP FB bullet might be.
Here's some practical bullet design data which, will prove very useful for someone wanting to test the 7mm BR for point-blank BR
competition - of course, this presumes one could either acquire desired jacket length, or, as George stated above, obtain/make a pinch-trim die, purchase longer jackets and pinch to the needed length . . . and, of course, either have, or, obtain a set of bullet swage dies.
Let's look at a pair of examples, of 100 Gr., .284" (7mm) flat-base bullets at 0.930" long, featuring [tangent] 8 caliber noses: first with a 0.060" me'plat/knock-out pin; then, 0.050" me'plat/K-O pin:
1) 0.060" me'plat, calculated G1 BC .324, barrel twist rate of 1:15.5" would deliver Sg1.5.
2) 0.050" me'plat, calculated G1 BC .337, barrel twist rate of 1:15.8" would deliver Sg1.5.
These numbers are based upon 3,000 FPS MV, and STD conditions. Getting a die maker to do a 0.050" me'plat could prove challenging.
No attempt has been made to calculate a desirable free-bore length, but very likely, for either form, ZERO would be desirable - a shorter nose (say 7 Cal. tangent, or, a secant type "trick") would/could increase the shank/bearing length. In most instances, the calculated BC is difficult to obtain - for the items I make, with two exceptions, real world BC has run between 0.010 and 0.015 lower than the calculations.
That brings us back to the expected performance differences and my frog-hair splitting argument with George ( he's a 7mm freak) - this comparison allows a 3200 FPS MV for the 100 Gr./.337BC 7mm bullet, vs. the standard .30 Cal 118/.330BC @ a measly 3050 FPS. The 200 Yd. drift for the 7mm calculates @ 0.33" per MPH; the 118 Gr. .30 Cal @ 0.36", a difference of 0.030", or, the equivalent of 0.0909 MPH velocity change . . . let's round it up to 0.1 MPH. Again, who is capable of doping THAT?!!? On a given day, EDGES work for only one individual - always, THE edge is between that persons ears.
In the end, WHY isn't anyone doing/testing this "stuff". . . RG
Here's some practical bullet design data which, will prove very useful for someone wanting to test the 7mm BR for point-blank BR
competition - of course, this presumes one could either acquire desired jacket length, or, as George stated above, obtain/make a pinch-trim die, purchase longer jackets and pinch to the needed length . . . and, of course, either have, or, obtain a set of bullet swage dies.
Let's look at a pair of examples, of 100 Gr., .284" (7mm) flat-base bullets at 0.930" long, featuring [tangent] 8 caliber noses: first with a 0.060" me'plat/knock-out pin; then, 0.050" me'plat/K-O pin:
1) 0.060" me'plat, calculated G1 BC .324, barrel twist rate of 1:15.5" would deliver Sg1.5.
2) 0.050" me'plat, calculated G1 BC .337, barrel twist rate of 1:15.8" would deliver Sg1.5.
These numbers are based upon 3,000 FPS MV, and STD conditions. Getting a die maker to do a 0.050" me'plat could prove challenging.
No attempt has been made to calculate a desirable free-bore length, but very likely, for either form, ZERO would be desirable - a shorter nose (say 7 Cal. tangent, or, a secant type "trick") would/could increase the shank/bearing length. In most instances, the calculated BC is difficult to obtain - for the items I make, with two exceptions, real world BC has run between 0.010 and 0.015 lower than the calculations.
That brings us back to the expected performance differences and my frog-hair splitting argument with George ( he's a 7mm freak
) - this comparison allows a 3200 FPS MV for the 100 Gr./.337BC 7mm bullet, vs. the standard .30 Cal 118/.330BC @ a measly 3050 FPS. The 200 Yd. drift for the 7mm calculates @ 0.33" per MPH; the 118 Gr. .30 Cal @ 0.36", a difference of 0.030", or, the equivalent of 0.0909 MPH velocity change . . . let's round it up to 0.1 MPH. Again, who is capable of doping THAT?!!? On a given day, EDGES work for only one individual - always, THE edge is between that persons ears.In the end, WHY isn't anyone doing/testing this "stuff". . . RG
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Fuj
New member
I test all the time but with my wild cats. I left the 7br years ago. thought about going
back to it when Sierra released the 100 grain varmint. In the past ten years though,
I've been playing with taking the 284 Winchester and shortening it to various lengths.
This version, I was playing with the guy's and made one the length of a 6.5 Creedmoor.
Still had some 100 grain Sierras, and did an anal sort. Hart had sent me a 30 Inch Max
Varmint blank, and I short stepped a 284 Whitley reamer. it has a .060" free bore. I do
all my own work, from chambers, to building BR type rifles on one piece aluminum
chassis.......I fire formed 300 Peterson cases in a mule barrel then loaded using N-135
and set the bullets to touch for the first range test. I shot the first target, then the
smaller target was for dropping one tenth of a grain to explore on either side of what
I thought looked good.......I have not done a seating depth test yet......Maybe in a couple
of weeks when the winds up here on Lake Erie give me a break......For what it's worth,
it's a 6 groove 12 twist barrel because Karen said they did not have a 4 groove button.
Yeah, jackets I doubt I'll ever see, but building a custom press anyway. Always another
cat to skin......Here are the first targets I shot last week.
back to it when Sierra released the 100 grain varmint. In the past ten years though,
I've been playing with taking the 284 Winchester and shortening it to various lengths.
This version, I was playing with the guy's and made one the length of a 6.5 Creedmoor.
Still had some 100 grain Sierras, and did an anal sort. Hart had sent me a 30 Inch Max
Varmint blank, and I short stepped a 284 Whitley reamer. it has a .060" free bore. I do
all my own work, from chambers, to building BR type rifles on one piece aluminum
chassis.......I fire formed 300 Peterson cases in a mule barrel then loaded using N-135
and set the bullets to touch for the first range test. I shot the first target, then the
smaller target was for dropping one tenth of a grain to explore on either side of what
I thought looked good.......I have not done a seating depth test yet......Maybe in a couple
of weeks when the winds up here on Lake Erie give me a break......For what it's worth,
it's a 6 groove 12 twist barrel because Karen said they did not have a 4 groove button.
Yeah, jackets I doubt I'll ever see, but building a custom press anyway. Always another
cat to skin......Here are the first targets I shot last week.
Attachments
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R.G. Robinett
"That'll never work."
Cool project, Fuj.
The late George Myer made some great wildcats based upon shortening the .284 Win. George's .30Myer, designed to meet the old NBRSA and still IBS Hunter Class capacity minimum of, "thirty-thirty", or 45.0/45.5 Gr. H2O, is a GREAT design: T.K. Nolan won several NBRSA Hunter National yardages and Grand Aggs using .30Myer chambered barrels. There was also a 6mm version - due to requiring some serious wildcatting knowledge (case making) not many people went with either.
For yours truly, experimenting is where the enjoyment/interest resides. RG
The late George Myer made some great wildcats based upon shortening the .284 Win. George's .30Myer, designed to meet the old NBRSA and still IBS Hunter Class capacity minimum of, "thirty-thirty", or 45.0/45.5 Gr. H2O, is a GREAT design: T.K. Nolan won several NBRSA Hunter National yardages and Grand Aggs using .30Myer chambered barrels. There was also a 6mm version - due to requiring some serious wildcatting knowledge (case making) not many people went with either.
For yours truly, experimenting is where the enjoyment/interest resides. RG
Bulletmonkey
New member
Jackets aren’t the issue they are available
Sierra stock # T1895F 7MM .880 LENGTH - FIN. JACKET from the Sierra Retail price list
I guess the 0.880” long jackets will make a great 100 grain bulllets
But…… Bulllet Making Dies are the real question to find someone to make them especially a FB core seating die
Sierra stock # T1895F 7MM .880 LENGTH - FIN. JACKET from the Sierra Retail price list
I guess the 0.880” long jackets will make a great 100 grain bulllets
But…… Bulllet Making Dies are the real question to find someone to make them especially a FB core seating die
geo.ulrich
Active member
The jackets are listed but try getting some in any type of real time, dies are not the problem I have made a few sets..
Fuj
New member
Straight from Sierra.....No jackets available at this time. Dealers will be notified first.
Reloading International has 3000 of 1.375" in stock.
For what it's worth.....The 100 grain FB Varmint shoots. The only thing I plan on
doing is a tighter point up on some and test. I received in another 2000, and
they are running .885". I'm shooting these with a 12 twist Hart. I'll see how all
this plays out over the next months into the match season. I may be contacting
Karen at Hart again and discuss money on having them cut a 14 twist button for
me.
George.....What has been the lightest 7mm you have played with ??
Reloading International has 3000 of 1.375" in stock.
For what it's worth.....The 100 grain FB Varmint shoots. The only thing I plan on
doing is a tighter point up on some and test. I received in another 2000, and
they are running .885". I'm shooting these with a 12 twist Hart. I'll see how all
this plays out over the next months into the match season. I may be contacting
Karen at Hart again and discuss money on having them cut a 14 twist button for
me.
George.....What has been the lightest 7mm you have played with ??
R.G. Robinett
"That'll never work."
WEIGHT (GRAINS) | 100 |
WEIGHT (GRAMMES) | 7 |
SECTIONAL DENSITY | 0.177 |
BALLISTIC COEFFICIENT C1 | 0.322 |
TWIST RATE FOR STABILITY FACTOR OF 1,5 | 16.9
Fuj - I got this a little cobbled-up, but useful. The twist, weight, BC, etc., were calculated based upon your provided length, and a [tangent] 8 caliber nose, 0.0625" me'plat, and specific gravity of construction 10.3 (for a bullet of these dimensions, using specific gravity of construction = 10.3 makes a 100 Gr. bullet.) These numbers will be very close/useful . . . you can see how much that WAY TOO FAST 1:12" twist is wrecking the precision. I also ran a comparison on Geoffery Kolby's/Border Barrels barrel twist calculator - George put me onto this many years ago - both calculators are in strong agreement. When this and the Tioga info closely correlate, the DATA has been gold! I am unable to get the Border Barrels graph to copy/paste here. Good shootin'! RG |
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geo.ulrich
Active member
I used 16" twist, barrels were not so bad getting but it took a little bit of arm twisting. The lightest was 85 grs but I felt it gave to much up so I kind of standardized 95-100
Fuj - I got this a little cobbled-up, but useful. The twist, weight, BC, etc., were calculated based upon your provided length, and a [tangent] 8 caliber nose, 0.0625" me'plat, and specific gravity of construction 10.3. These
numbers will be very close/useful . . . you can see how much that WAY TOO FAST 1:12" twist is wrecking the precision.
I also ran a comparison on Geoffery Kolby's/Border Barrels barrel twist calculator - George put me onto this
many years ago - both calculators are in strong agreement. When this and the Tioga info closely correlate, the DATA has been gold! I am unable to get the Border Barrels graph to copy/paste here.
Here's Geoffrey Kolbe's twist calculator:
http://www.geoffrey-kolbe.com/barrel_twist.htm
Good shootin' -Al
http://www.geoffrey-kolbe.com/barrel_twist.htm
Good shootin'
-Al