Duplicate 7-08 in a smaller bore?

[jpope02]

Why has nobody addressed the 6.5 PRC or the 284 Winchester?

 

[ntsqd]

I don't consider myself a BR or ELR class reloader, yet, but yeah been on and off pulling a Rockchucker handle for about 30 years.

I don't yet know if she's going to want to try it yet. This thread is about doing the prelim research to figure out the direction to take. 7-08 has been the intended chambering by default, but I got to wondering why not a 6.5 or smaller bore? With our range's notorious cross wind it couldn't hurt to have something that needs less doping. I built a 6.5 CM upper so I do have dies for that caliber.

Why has nobody addressed the 6.5 PRC or the 284 Winchester?

Point is to consider going with a smaller bore than 7mm, would prefer a short action, and the shooter is small in stature. Neither of those calibers really fit the desired result.

 

[XSIVSPD]

Just as an FYI, you could even go down to a 6mm creedmoor to reduce the recoil. This is for factory Hornady match eld-m loaded ammo. 10 mph crosswind at 90* angle

 

[LVJ76]

Just as an FYI, you could even go down to a 6mm creedmoor to reduce the recoil. This is for factory Hornady match eld-m loaded ammo. 10 mph crosswind at 90* angle

I don't think the light 108gr bullet will knock down the Rams, it has the velocity but the weight just isn't there.

 

[XSIVSPD]

That's true,i was just looking at kinetic energy, but really you need to match the momentum of the 7-08, not the KE

 

[XSIVSPD]

Hornady match 6.5 creed with 147g eld-m same conditions

 

[LVJ76]

Hornady match 6.5 creed with 147g eld-m same conditions

I think this one has whats needed

 

[elf]

Take a look at the 6.5 Grendel. Great accurcy!!

 

[ntsqd]

I know that down-range KE is what it takes to knock over the target, but a rather simple test is what is the KE at the muzzle? If any particular cartridge doesn't match or exceed the so-called "Gold Standard" cartridge, 7mm-08 with a 140 gr. (or heavier) bullet at the muzzle then it for sure won't have enough KE down-range unless it's self-propelled.

Then I am looking at what the recoil energy of different cartridges is in same weight rifles. The steelchickens forum really put this into perspective (thanks for that link!). Yeah, you probably can shoot a .460 Wby in a match and be sure to knock over the targets, but you're going to fire it 40 times in one match. What are the odds of you even hitting that 40th target after 39 punishing shots? Match Fatigue will certainly set in and reduce your score. It is a balancing act between enough power to knock over the targets while not having punishing recoil. In the match that we watched one guy was using a .257 Wby. He was new to the game and using the only rifle that he had. He was also pretty done before they got to the rams. I do not recall his even pinging one of them, clean misses on all five shots.

At first I didn't understand the interest in Momentum. KE and Momentum are calculated using the same two variables, mass and velocity, but then I began to see why the interest in Momentum over KE. In KE the velocity is very dominant in the result where in Momentum they are equally weighted. I did a simple spreadsheet experiment that showed me this. Using the velocity numbers posted just above I calculated both M & KE for the 147. Then using the KE as the desired match I backed out the required velocity needed for a 120gr. (This assumed the velocity decay rate would be the same, which it would not be, but for the desired purpose that wouldn't matter.) By 'adjusting' the velocity of the 120 to deliver the same KE as the 147 at each distance the Momentum suffered. Momentum of the 147 at 600 yards is 291,765, but the Momentum of the 120 at 600 yards is 263,613 even though they both have the same KE at that distance. It was at this point where the Momentum light bulb went on.
Take a garbage truck and and a kid on a bicycle. Their velocities are such that they both have the same KE, but their Momentums differ greatly. Which would you rather be hit by?

 

[Randy Tidwell]

I shot allot of Hi Power Silo in the 70s and 80s. About the time the 7-08 came out, several of us built one, my scores immediately went down on the rams, no from misses, but from hits and not going over.

After about six months of multiple fails, I pulled the barrel. Think I still have laying in the rafters somewhere. Never looked back.

If you're building a Silo gun, smaller bullet is not the answer. You can reduce the recoil with a muzzle break.

JMHO

 

[ntsqd]

No comps or porting according to the rules that I saw.

Found it, Rule 3.16.1 in LVJ76's attachment:

"Compensators and Muzzle Brakes - The use of compensators, muzzle brakes and barrel porting is prohibited, except in Air Rifle Silhouette competition. (The adjustment holes on the Boss-CR are not considered to be compensators, muzzle brakes or barrel porting.)"

 

[LVJ76]

I know that down-range KE is what it takes to knock over the target, but a rather simple test is what is the KE at the muzzle? If any particular cartridge doesn't match or exceed the so-called "Gold Standard" cartridge, 7mm-08 with a 140 gr. (or heavier) bullet at the muzzle then it for sure won't have enough KE down-range unless it's self-propelled.

Then I am looking at what the recoil energy of different cartridges is in same weight rifles. The steelchickens forum really put this into perspective (thanks for that link!). Yeah, you probably can shoot a .460 Wby in a match and be sure to knock over the targets, but you're going to fire it 40 times in one match. What are the odds of you even hitting that 40th target after 39 punishing shots? Match Fatigue will certainly set in and reduce your score. It is a balancing act between enough power to knock over the targets while not having punishing recoil. In the match that we watched one guy was using a .257 Wby. He was new to the game and using the only rifle that he had. He was also pretty done before they got to the rams. I do not recall his even pinging one of them, clean misses on all five shots.

At first I didn't understand the interest in Momentum. KE and Momentum are calculated using the same two variables, mass and velocity, but then I began to see why the interest in Momentum over KE. In KE the velocity is very dominant in the result where in Momentum they are equally weighted. I did a simple spreadsheet experiment that showed me this. Using the velocity numbers posted just above I calculated both M & KE for the 147. Then using the KE as the desired match I backed out the required velocity needed for a 120gr. (This assumed the velocity decay rate would be the same, which it would not be, but for the desired purpose that wouldn't matter.) By 'adjusting' the velocity of the 120 to deliver the same KE as the 147 at each distance the Momentum suffered. Momentum of the 147 at 600 yards is 291,765, but the Momentum of the 120 at 600 yards is 263,613 even though they both have the same KE at that distance. It was at this point where the Momentum light bulb went on.
Take a garbage truck and and a kid on a bicycle. Their velocities are such that they both have the same KE, but their Momentums differ greatly. Which would you rather be hit by?

With practice you do not tire after 40 rounds. Here in AZ, the State Shooting Championships we shoot 40 rounds Precision Rifle in the morning and then 40 in the Hunting class in the afternoon on both Saturday and Sunday. Also keep in mind the precision rifle is heavier than the hunting version.

The recoil of the 7mm-08 is pretty mild and you also get used to it.

Practice is key and as I mentioned before you can practice with the 22 LR on the smallbore range to get used to the weight of the rifle. I'm sure they also shoot smallbore every month so that will also help get in the rithym of the competition.

When practising, use the timer not just shoot at the silhouettes, like if you were at a match, it will help a lot

And I still recommend the 7mm-08, my wife is 5' 2" and 120 lbs, she is so used to the recoil now that she'll shoot a few rounds with my 7mm Rem Mag whenever we are at the range practicing, she says its more fun.

 

[blacktail 8541]

Take a hard look at the 25 Souper!

https://www.ballisticstudies.com/Knowledgebase/.25-08+.25+Souper.html

I built one for my hunting partner, it is a tack driver. Built on a Model 70 with a 9 twist Bartlen barrel. We were double checking sight in a couple weeks ago preparing for a Lope hunt, 3280fps.

He only shoots 100 grain Barnes TTSX's, but just like a 308, it is inheritly accurate.

I also have a 257AI that works really well.

I have a 25 souper with a Bartlen barrel and shoot the Barnes 100 ttsx, I am seeing the same as regard to velocity and accuracy. I get a lot of 1/2 to 3/4 inch groups at 200 yards.