## Comparing Calibres & Projectiles For F-Class

Started by ThunderDownUnder, January 09, 2011, 12:08:11 AM

#### ThunderDownUnder

I was searching for ballistic formulas to use in Excel in order to convert a table/chart Bryan Litz had created. This table displayed a selection of calibre/projectiles in a side by side comparison. I wanted to turn the table into a spreadsheet and then I discovered Robert's BfX() functions and the search was over! Finding this website was like finding gold and I effortlessly put together a spreadsheet to do exactly what I wanted.

Its available for download here: http://www.safclass.com.au/Spreadsheets/Drop+Drift+Recoil%20Calculator.xls

This is a screen shot the spreadsheet I put together for the caliber/projectile comparison.

Uploaded with ImageShack.us

I have a hunch this will be the first of many spreadsheets I will use to help me solve problems and to compare data in order to gain better results with my equipment.

Ian

#### admin

... it will be a real challenge to built a rifle that can launch a 90 grain .223 bullet. But when it flies stable the ballistics is unbeatable - for a paper punching F-Class purpose.

#### ThunderDownUnder

The first column in the spreadsheet is data from my 22BR and as you suggest it shoots very well. Great accuracy and very low recoil as it is in a rifle which uses a 1.25" parallel barrel. I use it at the shorter ranges and it really comes into a class of its own at 300 metres.

It didn't take long to modify the original spreadsheet and it now has the velocity at 1000 yards added to provide a more complete comparison for F-Class choices.

Ian

#### mman

Quote from: ThunderDownUnder on January 10, 2011, 07:00:47 AM
The first column in the spreadsheet is data from my 22BR and as you suggest it shoots very well. Great accuracy and very low recoil as it is in a rifle which uses a 1.25" parallel barrel. I use it at the shorter ranges and it really comes into a class of its own at 300 metres.

It didn't take long to modify the original spreadsheet and it now has the velocity at 1000 yards added to provide a more complete comparison for F-Class choices.

Ian

Was it hard to get 22 BR to group with 90 grain bergers? How about measuring muzzle velocities? They say that 90 grain VLDs are a challenge for the chronographs.

#### ThunderDownUnder

#4
It has a chamber cut for the 90gr Berger VLDs and I did not have any trouble getting it to group. I use Varget (ADI2208) and CCI 450 magnum primers for a velocity of 3160fps. This load forms a one ragged hole group at 100 metres. In calm conditions it shoots out to 900 metres with match winning accuracy but if the wind blows I take out the 284 Shehane and the 180gr VLDs.

I use a CED2 chronograph with a IR light source I made myself and it records the 90gr projectiles every shot without missing a beat.

Ian

#### mman

#5
How about muzzle velocity variations and false readings? Do you have any first hand experience of accurate barrel life? 7" twist barrel? I'm asking these questions because i've been interested in that combination for a long time. Now I'm using 6.5-284 and berger 140 VLDs. Actually I just ordered 140 JLK VLDs. Those bullets should have G7 bc of 0.321. For that caliber it is no problem to get muzzle velocities over 950 m/s. That's pretty good ballistics but for now I haven't find accuracy with bergers. At least 20+ mm groups / 100m does not feel good when my 22 PPC nails below 10 mm groups with 70 gr. bergers.

#### ThunderDownUnder

I have found the CED2 with IR screens to be very reliable and repeatable. Bryan Litz used the CED2 to gather his G7 data in his first book. Interestingly the 22BR when tested at its optimum target load, varied only a few fps with two consecutive shots giving the same velocity. Out of all the calibres I shoot, the 22BR target load gave the best SD and ES and that includes 7mm and 6.5mm calibres.

I use a 32" Krieger (1.25" parallel) 7 twist barrel and a Barnard Model P action and as yet have not worn out the barrel with only 600 rounds fired through it so far. I have a Hawkeye borescope and the barrel still looks in good condition with minimal throat wear. The 22 cal, Berger, 90gr VLDs have slightly higher BCs than any of Berger's 6mm offerings and I'm surprised more shooters aren't using them. Higher BC combined with the easily achieved high velocity makes it a pretty good choice for days when the wind is mild.

Ian

#### mman

#7
Quote from: ThunderDownUnder on May 09, 2011, 10:50:49 AM
I use a 32" Krieger (1.25" parallel) 7 twist barrel and a Barnard Model P action and as yet have not worn out the barrel with only 600 rounds fired through it so far. I have a Hawkeye borescope and the barrel still looks in good condition with minimal throat wear. The 22 cal, Berger, 90gr VLDs have slightly higher BCs than any of Berger's 6mm offerings and I'm surprised more shooters aren't using them. Higher BC combined with the easily achieved high velocity makes it a pretty good choice for days when the wind is mild.

Ian

You are right. On paper that is almost unbeatable combination when recoil is a factor. For you it seems to be that in practice also. I think many shooters are doubtful considering fast 7" twist and accuracy. But with your good commends it may be that I'll build one of those 22 BR rifles someday. I've always liked small bore calibers. It's nature of scale that it's easier to get more muzzle velocity in small bores with better barrel life and shorter barrel. Components are cheaper for small bores, barrel heating isn't so much of a problem and suppressors work better when case ins't too big. It's also much easier to build light gun with small bore. There is only one bad thing to say about small bores is terminal performance when it comes to controlled expansion. For a small game hunter small bore bullets are always too explosive or not effective enough. And if terminal performance is good exterior ballistics sucks.. That's my challenge for bullet makers..

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