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Shano Shah
22-07-2010, 02:59 AM
Dear Members,

Remington 24” Sako 22” and Mauser 20” in Cal:.308 Win gave same velocities with very little difference.

I have read several articles where people have tested 308 and from 26" down to 20" there was little to no difference in velocity.

I don't see why the 7mm-08 should be any different.

Please advise.

Regards.

Apalo
22-07-2010, 04:44 PM
With all due respect sir, looking for an other expert :)

Shano Shah
23-07-2010, 01:34 AM
I have not used 7mm-08. It’s not a common caliber in our country; asking forums opinion so if any member is using it can give his opinion.

Skeeter60
23-07-2010, 11:23 AM
No two barrels give the same velocity irrespective of barrel length. We discussed it earlier also. There are too many variables, like chamber being too tight or lose, the leade or throat being too long or short, there being high and low spots in the barrel and the groove or bore dia having variations in the barrel.
If the effect of barrel length on velocity is to be checked then a 26 in ch long barrel should be chosen and after chronographing ten or so bullets with a given bullet with all parameters constant like propellant, primer, case and bullet; cut the barrel 2 inches shorter and proceed and repeat till down to what ever lengths you want to compare and you will then have the effect of barrel length vs velocity.
I have 7mm mag rifles 4 of them and each gives different velocities with the same bullet, I used to have another one with same barrel length and would shoot 250 feet slower than the other rifles with all bullets, so you you know why it is history.
Bigger bores require relatively shorter barrel lengths to achieve optimum velocity , this is because the bore efficiency is better as the gas pressure has a bigger surface to exert upon.
Each caliber should be discussed separately as different parameters come into play

Shano Shah
23-07-2010, 03:04 PM
Sir, you have explained me before that no two-barrels match each other like a finger prints.

My question is Acceptable Barrel Lengths.

In my opinion 7mm Magnums minimum barrel length should be not less that 24” due to propellant quantity. Specially when using Heavy bullet with slow burning propellant. Keeping pressure at bay and achieving maximum efficiency.

In case of 7mm STW 26” barrel is consider Standard length and even 28” to 30”barrels are used when shooting heaver bullets such as Berger 180gr VLD's at extreme range.

There is a practical limit to most things in life. Even a 26" barrel on a long action can be annoying when moving in the field.

Coming to my main question is 7mm-08 in 20” barrel length will achieve acceptable efficiency and velocity using 4895,4064,4320 with lighter bullets 130 –139 grains

Skeeter60
23-07-2010, 05:36 PM
Shano Shah

A 7mm08 will give reasonable velocities and will be very handy.
If you remember we discussed earlier why the makers have returned to 24 ins from 22 ins in the 270.
Incidently the heavier bullets are effected less, it is the lighter bullets which suffer more with shorter barrels