OzFclass

Given the current muzzle energy restriction in Qld I thought it timely to compare the highest BC Bullets for both calibres. The normal comparison for F-Open calibres is to use calculated wind drift at 1000 yards for a given 10 mph crosswind. Thats what I have used for the following data calculated on the most popular bullets used for this class.

I will also include calculated recoil velocity and energy, these figures are only good for a approximate comparison as different powder burning rates, cases, etc, apply in the real world. I assume a weight of 22 pound for the rifle used in all recoil calcs.

Bullets Compared

1. 7mm 180gr Hybrid G7 BC = 0.345
2. 30 cal 215gr Hybrid G7 BC = 0.356
3. 30 cal 230gr Hybrid G7 BC = 0.380

Note: I have found pointing the 30 cal bullets gives approx 5% increase in BC.

All Bullets Launched At Max Velocity Permitted In Qld

1. 7mm 180gr @ 2960fps = 55.13" of drift at 1000 yards
2. 30 cal 215gr @ 2710fps = 57.38" of drift at 1000 yards
3. 30 cal 230gr @ 2625fps = 55.19" of drift at 1000 yards

Even though the 30 cals are severely speed restricted in Qld they still closely match the faster 7mm.

Calculated Recoil At Velocities Shown Above (approx)

1. 7mm 180gr produces 5.56fps for 10.59 ft-lb
2. 30 cal 215gr produces 5.71fps for 11.15ft-lb
3. 30 cal 230gr produces 5.79fps for 11.45ft-lb

Interestingly the 30 cal's can still compete ballistically with the 7mm's for the bullets used in this comparison, even though severely disadvantaged with the velocity restriction.

From testing and development that I done with both of these calibres and given the case selection required to reach 2960fps, (bigger than a 284W). I would think the 30 cal's although just a fraction behind the 7mm's for least wind drift would exceed them for longer barrel life. The short bearing surface of the 30 cal bullets and slower burning powder, lower velocity, may well mean that the 30 cals barrels would see well over 2000 round counts before requiring replacement.

If range restrictions are eventually lifted and higher velocities allowed then the 30 cals come into their own with only the additional recoil disadvantaging some recoil sensitive shooters.

This is simply my take on the available bullets for both calibres and I would love to hear differing opinions and options from shooters who have developed other loads.

Ian

What an interesting post Ian! Given my ability or, more precisely, lack thereof in deciding where to point the rifle I doubt that I'd notice .06" in wind drift at 1000yds. Looks like it might be safe to proceed with the 30-'06AI project.

Barry

Ian

Personally,I am not a fan of reading too much into this type of data.

My point is that Marty L uses a standard 284win with 180g VLD's doing 2830fps. He came second in the world at Raton, missing first place on "x"'s
At that shoot there were a lot of blokes using 7mm and 30 cal magnums who got hammered.
To me you need a very accurate rifle and the ability to shoot top level consistently.

My thoughts
Cam from Qld......the best state in the nation

Cameron Mc wrote:Ian

Personally,I am not a fan of reading too much into this type of data.

My point is that Marty L uses a standard 284win with 180g VLD's doing 2830fps. He came second in the world at Raton, missing first place on "x"'s
At that shoot there were a lot of blokes using 7mm and 30 cal magnums who got hammered.
To me you need a very accurate rifle and the ability to shoot top level consistently.

My thoughts
Cam from Qld......the best state in the nation

100% correct slightly superior ballistics alone will not out perform a good inform shooter with an accurate rifle. If that were not so every F std match would be a draw!:D
Keith H.

I agree with Cam ... Qld is the best state in the nation 😉. Lol!

I usually agree with Cam and Keith, but this is one of those times when I reluctantly have to differ.

All else being equal, and I include rifle accuracy and wind-reading ability in that, then the load with the lowest wind deflection will win. For example if Marty had had his Bergers going 100 fps faster at Raton, with the same accuracy, I believe he would have won.

And my last Queens was in Tassie where I couldn't get the 180 Bergers going accurately, so ended up using the 168s at the longs. Watching Mark Fairbairn virtually shoot through the wind at 900 and 1000 on the last day with his magnum convinced me that accuracy may be king, but velocity helps too.

Alan

bsouthernau wrote:What an interesting post Ian! Given my ability or, more precisely, lack thereof in deciding where to point the rifle I doubt that I'd notice .06" in wind drift at 1000yds. Looks like it might be safe to proceed with the 30-'06AI project.

Barry

Barry, my 30-06AI project was aimed at replacing my 7mm Shehane and overcoming the problematic Lapua 6.5-284 brass.

I run the 215gr Hybrids at 2800 fps without any problems and I will now test at 2700 fps to see if there is an accuracy node to found. I have not tried the 230's in the 30-06AI because they are shooting 0.25 moa from my 300WM at 2850 fps and cant see any reason to take a backward step. Having said that, Steve Blair (USA) has used them in the 30-06AI, and if memory serves me correctly says they are deadly accurate.

Personally I think the Qld limit of 2625 fps for the 230's should be available to the 30-06AI. I think it is probably worth trying and finding out if the case can handle the pressure for 10+ reloadings. For me I will stick with the 215's & 200's which was my reason for developing the 30-06AI. The good news is that if you want to compete in Qld, then the 30-06AI is probably all the gun you need for that state until things change.

Ian

AlanF wrote:I usually agree with Cam and Keith, but this is one of those times when I reluctantly have to differ.

All else being equal, and I include rifle accuracy and wind-reading ability in that, then the load with the lowest wind deflection will win. For example if Marty had had his Bergers going 100 fps faster at Raton, with the same accuracy, I believe he would have won.

And my last Queens was in Tassie where I couldn't get the 180 Bergers going accurately, so ended up using the 168s at the longs. Watching Mark Fairbairn virtually shoot through the wind at 900 and 1000 on the last day with his magnum convinced me that accuracy may be king, but velocity helps too.

Alan

I think you missed my point Allan, what I said in essence was that ballistics alone will not beat an inform talented shooter with a highly accurate rifle with slightly inferior ballistic performance. I did not mean or say that ballistics were not important. So many shooters, usually the less experienced believe that the all important factor is ballistic performance. While ballistic performance is very important my point & I think Cam's point was that the shooter must "drive" the rifle correctly first & foremost. I think that the main focus should be on the shooter's performance with Ballistic performance coming in a close second.
Keith H

I agree with Keith, having the best rifle wont make up for poor wind reading skills.

I had a few boxes of 230gr Hybrid Target projies turn up today!!

KHGS wrote:...I think you missed my point Allan, what I said in essence was that ballistics alone will not beat an inform talented shooter with a highly accurate rifle with slightly inferior ballistic performance. I did not mean or say that ballistics were not important...

Fair enough.

But I think when choosing a new chambering to shoot at the top level, you should seriously consider what will give the best ballistic advantage. I know that when I get a new 7mm barrel, I'll firstly try the highest BC projectile available at the highest velocity the 284 primer pockets will stand. If that is not sufficiently accurate, then I'll drop the velocity or go to the next highest BC projectile etc. Having a ballistic advantage will increase your scores provided that it doesn't come with too much recoil or reduced accuracy.

Otherwise, we'd all be shooting 6BRs!

Alan

Fair enough.

But I think when choosing a new chambering to shoot at the top level, you should seriously consider what will give the best ballistic advantage. I know that when I get a new 7mm barrel, I'll firstly try the highest BC projectile available at the highest velocity the 284 primer pockets will stand. If that is not sufficiently accurate, then I'll drop the velocity or go to the next highest BC projectile etc. Having a ballistic advantage will increase your scores provided that it doesn't come with too much recoil or reduced accuracy.

Otherwise, we'd all be shooting 6BRs!
Alan

The experienced inform shooter on the day would still win!!! Lets not forget the element of luck too, one must always have that & be able to capitalise on it when you have it.
Keith H.

Alan,
You have seen the models we did to compare rifles and I take it you believe in them. When the scores are up there (>59 average) and only dropping 2-8 over a queens there would be lucky to be 1 point between a 284 and a RSAUM. (Model it and take a look). This one point may well make a difference in some fields but most of our Queens are won by more than a point and this is what Keiths many years of experience tells him.

The big question is does that 1 point gain in BC come with issues that may cost that (or more) for you. Yes large recoil is one thing but so is over bore cases. These are harder to get right (in all temperatures) and take another skill level in this game. The Poms and Yanks all struggled with the 7-WSM's in Raton where the temps varied wildly (especially ground temp was incredible - cool air and very hot ground - ammo and rifles laid on the ground literally cooked - blowing primers everywhere.) The RSAUMs seemed about the upper limit for consistency but even then I feel the 284 (and 308's) shone in the consistent accuracy stakes through all the conditions. It is not JUST about BC but as Keith said the whole package. Who is in form and who can accurately deliver the most shots. Confidence in the rifle is another and the 284 gives many thousands of rounds of accurate lifetime in many conditions to gain confidence and score well (as I believe the 30 cal WSM, 30-06 and 30-284 will as well - some even better).

In Ians comparisons above - take any of these to the line and certainly the best shooter (in tune with his rifle and wind etc ) will win on the day.

There is of course a much bigger difference between a 6BR and these options-----

bsouthernau wrote:What an interesting post Ian! Given my ability or, more precisely, lack thereof in deciding where to point the rifle I doubt that I'd notice .06" in wind drift at 1000yds. Looks like it might be safe to proceed with the 30-'06AI project.

Barry

Barry I tried an experimental Qld load to yield 2720 fps using the 215gr Hybrids and it worked a treat. Looks like the 215s will still work fine at 80fps less than I would normally run. I will run the load thru the chrono today and see if the velocity is within the muzzle energy restriction. The reduction in recoil was quite evident which was surprising considering only a 70-80fps drop in velocity. Still supersonic out to 1200 yards which is as far as my calculated table went.

Ian

I chronoed some 180 bergers today and got a 3001fps ave, quite nice to shoot as well.

IanP wrote:
Barry I tried an experimental Qld load to yield 2720 fps using the 215gr Hybrids and it worked a treat. Looks like the 215s will still work fine at 80fps less than I would normally run. I will run the load thru the chrono today and see if the velocity is within the muzzle energy restriction. The reduction in recoil was quite evident which was surprising considering only a 70-80fps drop in velocity. Still supersonic out to 1200 yards which is as far as my calculated table went.

Ian

Thanks Ian. I'm setting off early tomorrow for a delightful drive through the mountains to deliver all my stuff to Mark Sewell for his skillful ministrations. Looking forward to the experimentation - based on your advice - once I get it back.

Barry