6.5-06 vs 6.5X284 vs 6.5 Sherman

[Trickymissfit]

A 6.5 Sherman is a creation of elkaholic on LRH. It is an '06 type case improved and necked to 6.5 cal. It is his design thus he affixed the name to it.

considering the fact that there are at least a dozen improved 6.5-06 rounds out there; where does it fall in? The 6.5-06 is slightly overbore (not enough to matter much as it's very accurate). The improved 6.5-06 is a little overbore when using light bullets, and the 6.5-.284 is really about spot on (even with a screwed up case design). It's also kinda surprising that nobody's fooling around with the 6.5x57AI; which is probably better (also known as the .260 AAR). Velocities are similar to the 6.5-06 AI (maybe a hundred feet per second slower at the most), and are easilly formed from generic .257 Roberts brass. Then there is also the 6.5-.270AI beast (that might be a Mashburn case) to keep us all thinking<g>!
Back to the 6.5 Sherman. How does Mr. Sherman setup the shoulders and the taper per inch in his design? It's important to keep the vortex of the flame path inside the first half of the case neck for barrel life and accuracey.
gary

 

[Aldon]

At that level of informational request I have to punt.

PM Elkaholic - Sherman and the next time he is on the forum he will likely help you out.

 

[elkaholic]

considering the fact that there are at least a dozen improved 6.5-06 rounds out there; where does it fall in? The 6.5-06 is slightly overbore (not enough to matter much as it's very accurate). The improved 6.5-06 is a little overbore when using light bullets, and the 6.5-.284 is really about spot on (even with a screwed up case design). It's also kinda surprising that nobody's fooling around with the 6.5x57AI; which is probably better (also known as the .260 AAR). Velocities are similar to the 6.5-06 AI (maybe a hundred feet per second slower at the most), and are easilly formed from generic .257 Roberts brass. Then there is also the 6.5-.270AI beast (that might be a Mashburn case) to keep us all thinking<g>!
Back to the 6.5 Sherman. How does Mr. Sherman setup the shoulders and the taper per inch in his design? It's important to keep the vortex of the flame path inside the first half of the case neck for barrel life and accuracey.
gary

That is one of the good features of this cartridge and why I have now fired 1000 rounds thru it with no apparent loss of accuracy........ Rich

 

[loaders_loft]

Aldon have you shot that 6.5 yet?

 

[Bart B]

The 6.5-06 is slightly overbore (not enough to matter much as it's very accurate). The improved 6.5-06 is a little overbore when using light bullets, and the 6.5-.284 is really about spot on (even with a screwed up case design).

The term "overbore" is often used, but how it's determined is usually based on guessing and opinion. Which is why I asked a noted riflesmith many years ago if there's any standard it's supposed to be referenced to.

Elmer Shook told me that bore capacity for a given bore diameter is one grain of powder for each square millimeter of the bore diameter's cross sectional area. And any caliber barrel shooting max loads whose powder charge weight producing best accuracy was at bore capacity would deliver about 3000 rounds of best accuracy. This is for barrels that start out shooting no worse than 1/4 MOA at 100 yards. Less accurate barrels tend to have longer barrel lives.

So I did some checking on this. Sure enough, popular 22, 24, 26, 28 and 30 caliber competition cartridges whose powder charge weight was at their bore capacity seemed to last about 3000 rounds of best accuracy. Double the charge weight for a given caliber and barrel life is reduced to 1/4th as many rounds.

If Kevin Thomas reads this, maybe he would share with us how often the test barrels in Sierra Bullets' rail guns got replaced when their accuracy level with "standards" dropped off.

 

[tulku]

I bought a used 6.5 06 AI that was used with 140 Gr. bullets in 1000 Yard Competition . The fellow who sold it to me got 3150 FPS with 140 Gr. Sierras out of the 30 Inch Barrel . Don't know how much he was pushing it . It has an 8.5 Twist Barrel and it does not shoot 140 well at 100 Yards for me ( don't know what it will do at Long Range yet ) . It shoots 107s into one hole at 100 Yards .... go figure . Since my goal is Varmints , I really don't mind using light 6.5 Bullets .

 

[Bart B]

I bought a used 6.5 06 AI that was used with 140 Gr. bullets in 1000 Yard Competition . The fellow who sold it to me got 3150 FPS with 140 Gr. Sierras out of the 30 Inch Barrel . Don't know how much he was pushing it . It has an 8.5 Twist Barrel and it does not shoot 140 well at 100 Yards for me ( don't know what it will do at Long Range yet ) . It shoots 107s into one hole at 100 Yards .... go figure . Since my goal is Varmints , I really don't mind using light 6.5 Bullets .

How big is that hole?

If it don't shoot well at short range, it won't shoot well at long range; with one exception.

No way do bullets at the edge of a virtual short range group know how to change direction and go back into the center of a way down range group; virtual or on paper. This appllies to windage and elevation spreads with front locking bolt action rifles.

Vertical ones don't apply when you're using rear locking British SMLE's with large muzzle velocity spreads; they're famous for shooting much better at long range than short range.

 

[elkaholic]

I bought a used 6.5 06 AI that was used with 140 Gr. bullets in 1000 Yard Competition . The fellow who sold it to me got 3150 FPS with 140 Gr. Sierras out of the 30 Inch Barrel . Don't know how much he was pushing it . It has an 8.5 Twist Barrel and it does not shoot 140 well at 100 Yards for me ( don't know what it will do at Long Range yet ) . It shoots 107s into one hole at 100 Yards .... go figure . Since my goal is Varmints , I really don't mind using light 6.5 Bullets .

3150 is about right for a max load with a 30" barrel. I get 3200 out of my 6.5 Sherman in a 26". I should easily get 3350 out of a 30"......Rich

 

[tulku]

How big is that hole?

If it don't shoot well at short range, it won't shoot well at long range; with one exception.

No way do bullets at the edge of a virtual short range group know how to change direction and go back into the center of a way down range group; virtual or on paper. This appllies to windage and elevation spreads with front locking bolt action rifles.

Vertical ones don't apply when you're using rear locking British SMLE's with large muzzle velocity spreads; they're famous for shooting much better at long range than short range.

Well Bart , it took awhile to find my old targets but here is what I got at 100 Yards with 4 shot Groups all shot at 20X : Sierra 142 Gr Match / 0.64 In. , Cauterrucio 141 Gr / 0.98 In . , Amax 140 Gr. / 0.47 IN . , Caut. 128 GR. / 0.34 inch , Sierra 120 Gr. Match / 0.31 Inch. , Sierra 107 Match / 0.14 In. Not much development time yet due to a lot of Medical Problems , but it looks promising . Also , I'm not quite used to the 2 Oz. trigger . Former Owner said his 140 Gr . Sierra Match Groups were in the 3s at 100 yards . I did shoot some of his Loads and did not get those results , but I'm sure he had a lot of experience with that Rifle . He shot a 6.0 inch Group in 1000 Yard Competition with that Rifle & Scope . He also said a lot of these Rifles do not Group super at 100 yards , but would "fall asleep " at 1000 . Never had experience with 1000 Yard Competition , so I just don't know .

 

[Bart B]

He shot a 6.0 inch Group in 1000 Yard Competition with that Rifle & Scope . He also said a lot of these Rifles do not Group super at 100 yards , but would "fall asleep " at 1000 . Never had experience with 1000 Yard Competition , so I just don't know .

According to Sierra Bullets, their products "fall asleep before they reach the 100 yard point. I've a hard time believing any bullet would "stay awake" for the first 999 yards (or even 900) of its flight then "go to sleep" in the next yard (or 100 of 'em).

Does he know how those bullets at the outer edge of a short range group know which way to head back towards center?

 

[loaders_loft]

Guys if you want to talk about your sleepy bullets then go start a thread about it in the appropriate section. This thread is about 6.5 cartridges so please don't high jack it. I revived this because I wanted to know if a particular rifle ever got fired.

 

[big mike 2121]

Elkaholic, is the 6.5 sherman accurate at all ranges? say from 1 to 200 and out? what does the fireforming do for your barrel life?

 

[Aldon]

Sorry it has taken so long to respond. The transfer and getting settled has kind of taken up most of my time over the past year.

I have taken the 6.5-06 to the range and have had no luck getting it to shoot well.........but yesterday I finally tried some Berger 140's with RL-22. I believe I am onto something with this combo but need to load some a little hotter. Jamming into the lands seems to be the way it likes it.

I hope to load and take it to the range again this week and if I have no luck. she is going to the Smith to see if the original work needs redone or tweaked.

 

[Trickymissfit]

The term "overbore" is often used, but how it's determined is usually based on guessing and opinion. Which is why I asked a noted riflesmith many years ago if there's any standard it's supposed to be referenced to.

Elmer Shook told me that bore capacity for a given bore diameter is one grain of powder for each square millimeter of the bore diameter's cross sectional area. And any caliber barrel shooting max loads whose powder charge weight producing best accuracy was at bore capacity would deliver about 3000 rounds of best accuracy. This is for barrels that start out shooting no worse than 1/4 MOA at 100 yards. Less accurate barrels tend to have longer barrel lives.

So I did some checking on this. Sure enough, popular 22, 24, 26, 28 and 30 caliber competition cartridges whose powder charge weight was at their bore capacity seemed to last about 3000 rounds of best accuracy. Double the charge weight for a given caliber and barrel life is reduced to 1/4th as many rounds.

If Kevin Thomas reads this, maybe he would share with us how often the test barrels in Sierra Bullets' rail guns got replaced when their accuracy level with "standards" dropped off.

interesting comments, and well taken. But can I add here?

One of the single greatest shooters of all time chimed in about the subject, and Ackley wrote about it in his book Hand Book For Shooters & Reloaders. Homer Powley is not a name to be taken lightly in the shooting world (I miss him), and he said that he felt that he felt bore capacity was linked to expansion ratios during the powder burn. High expansion ratios ment longer barrel life, and of course lower expansion ratios ment shorter barrel life. Ackley states that in many cases low expansion ratios ment a slight increase in velocity while gratly reducing barrel life, and as well being inflexable (as in being critical).

Ackley also states there is no set way to determine max case capacity for a certain bore size. He does speak of the three to one factor, but also states there really is nothing written in stone regarding this issue. (note: he was refering to 1/3rd of the bullet weight being the max powder capacity in a case, or 50 grains for a 150 grain bullet). He speaks of the 22 bore having a max capacity of 35 grains of powder, and what happens with 40 grains of powder.

I won't go into the chapter a lot here, but it's a good read, and will make you dig into your log books to compair notes. Looks like Parker is on track. I will reread this tonight and probably wear my fingers out on the calculator.
gary