Who else hunts the west with a black rifle?

[Loper]

View attachment 774412
They don’t have to be heavy, that’s a full 10 round mag, bolt action, 6x45View attachment 7744134 shots at 300 yards. I’ll let you know how it does on an animal when I catch one slipping. It is a dream to carry.

Is the lightweight one you have a semi auto or hand cycled?

 

[Taudisio]

Is the lightweight one you have a semi auto or hand cycled?

You can think of it as a straight pull bolt action.

 

[RockAndSage]

You can think of it as a straight pull bolt action.

So, all the normal parts of an AR, minus the gas block/gas tube? No other changes to the action?

 

[Taudisio]

So, all the normal parts of an AR, minus the gas block/gas tube? No other changes to the action?

Starting from the front of the rifle, NO- gas port, gas block, gas tube, bolt stop/release, buffer retainer, buffer, buffer spring.

The buffer tube is completely empty and could be a folder if I decided. The bolt carrier is chopped in half, so it doesn’t even go into the tube. There is no gas system in the gun.

 

[TaperPin]

Those gasless AR’s are super cool.

I’m not an AR fan, but put hem together for the kids - no self respecting young dude would be without one. Now that AR10 components have come way down in price, I will probably end up building an accurate 6.5 creed or 7mm08 for one of them to hunt with.

 

[11boo]

I quit packing the AR10 cause it was a pig. My SFAR is less piggy and will go hunting.

 

[RockAndSage]

Starting from the front of the rifle, NO- gas port, gas block, gas tube, bolt stop/release, buffer retainer, buffer, buffer spring.

The buffer tube is completely empty and could be a folder if I decided. The bolt carrier is chopped in half, so it doesn’t even go into the tube. There is no gas system in the gun.

Without the buffer/spring, how is the BCG going forward, after you pull it back? Do you have it fixed to the charging handle somehow?

 

[Taudisio]

Without the buffer/spring, how is the BCG going forward, after you pull it back? Do you have it fixed to the charging handle somehow?

It has a left side charging handle, fire, pull back and eject, push forward and it loads a new round from the magazine. Just like a bolt action, except you don’t have to lift up. I don’t have a video in action, but I have some where you can hear me working the bolt.

 

[RockAndSage]

It has a left side charging handle, fire, pull back and eject, push forward and it loads a new round from the magazine. Just like a bolt action, except you don’t have to lift up. I don’t have a video in action, but I have some where you can hear me working the bolt.

Ah, that makes total sense now. Thought you were using a normal charging handle. Very cool setup man.

 

[Taudisio]

Ah, that makes total sense now. Thought you were using a normal charging handle. Very cool setup man.

It wasn’t my idea, just my tweaks on the original design.

Ultralight Ultralight Rifles

I posted some info on the 77TMK thread about my experience on trying out the 77TMK on this black bear. There was some interest in the rifle used so I'm posting some info about the whys and hows on some of what I've put together over the last year or so. I've been carrying lightweight bolt...

rokslide.com

 

[11boo]

It wasn’t my idea, just my tweaks on the original design.

Ultralight Ultralight Rifles

I posted some info on the 77TMK thread about my experience on trying out the 77TMK on this black bear. There was some interest in the rifle used so I'm posting some info about the whys and hows on some of what I've put together over the last year or so. I've been carrying lightweight bolt...

rokslide.com

I remember that thread, pretty great ideas in there. Does the bolt ever unlock itself when fired? Seems unlikely.

I’m definitely going to use the sfar for my cow tag, if I can go.

I weighed this old .308 dpms once. The scope/rings are steel IOR stuff. Heavy.
That gun weighed 11 lbs loaded. I lost 1.2 lbs going with a lighter 1x4 and Al mount.

 

[Taudisio]

I remember that thread, pretty great ideas in there. Does the bolt ever unlock itself when fired? Seems unlikely.

I’m definitely going to use the sfar for my cow tag, if I can go.

I weighed this old .308 dpms once. The scope/rings are steel IOR stuff. Heavy.
That gun weighed 11 lbs loaded. I lost 1.2 lbs going with a lighter 1x4 and Al mount.
View attachment 774933

It hasn’t unlocked yet, and I have probably around 25 miles packing it around between both bear seasons and this last week of deer season. I run my reloads on the longer and hotter end of what is possible, so sometimes I have to give it more beans while closing the bolt, but my 5.56 version doesn’t have that problem. No issues with the bolt coming open, or hard time ejecting (since I backed it down a few tenths of a grain).

 

[Thegman]

I remember that thread, pretty great ideas in there. Does the bolt ever unlock itself when fired? Seems unlikely.

I’m definitely going to use the sfar for my cow tag, if I can go.

I weighed this old .308 dpms once. The scope/rings are steel IOR stuff. Heavy.
That gun weighed 11 lbs loaded. I lost 1.2 lbs going with a lighter 1x4 and Al mount.
View attachment 774933

The bolts stay completely locked upon firing until you pull back the charging handle. There are no gas system forces driving the bolt carrier, so it doesn't move until you move it.

The bolt -can- get bumped open while carrying in certain situations, especially rough country, but like Taudisio said, not generally an issue. When I'm packing up a mountain, my rifle is slung on the right side of my pack frame. I do check the bolt periodically to make sure it's not bumped open. Not something I've seen for a while, but a habit I've developed.

 

[Rotnguns]

I think you make compelling points. However, if I had a 300 yard shot at an elk (longest shot I would take with my confidence level) I would prefer my .308 over either the 6.5 GR or the 6 ARC. Not to say either of those rounds wouldn't do the job, but the .308 has considerably more momentum and kinetic energy at that range. Of course, that means a heavier AR 10 platform, so there is that....

To clarify, because mechanical engineers like this sort of thing:

Translational Kinetic Energy = ½ mass * (velocity squared), where mass and velocity units are slugs and ft/sec, respectively. KE will be returned in units of ft-lb.

Linear Momentum = Mass*Velocity , where mass is in slugs and velocity is in ft/sec. Linear Momentum will be in units of slug-ft/sec .

Comparing a few factory loads from Hornady:

For the .308 with 178 grain eld-x, at 300 yards: 2145 ft/sec, 1818 ft-lb, 1.69 slug-ft/sec

For the 6.5 GR with 123 gr sst, at 300 yards: 2090 ft/sec, 1193 ft-lb, 1.14 slug-ft/sec

For the 6 ARC with 105 gr boat tail hollow point, at 300 yards: 2260 ft/sec, 1190 ft-lb, 1.05 slug-ft/sec.



Compared to the 6.5 GR, the .308 has 52% more KE and 48% more linear momentum at 300 yards.

Compared to the 6 ARC, the .308 has 53% more KE and 61% more linear momentum at 300 yards.

 

[Formidilosus]

To clarify, because mechanical engineers like this sort of thing:

Translational Kinetic Energy = ½ mass * (velocity squared), where mass and velocity units are slugs and ft/sec, respectively. KE will be returned in units of ft-lb.

Linear Momentum = Mass*Velocity , where mass is in slugs and velocity is in ft/sec. Linear Momentum will be in units of slug-ft/sec .

Comparing a few factory loads from Hornady:

For the .308 with 178 grain eld-x, at 300 yards: 2145 ft/sec, 1818 ft-lb, 1.69 slug-ft/sec

For the 6.5 GR with 123 gr sst, at 300 yards: 2090 ft/sec, 1193 ft-lb, 1.14 slug-ft/sec

For the 6 ARC with 105 gr boat tail hollow point, at 300 yards: 2260 ft/sec, 1190 ft-lb, 1.05 slug-ft/sec.



Compared to the 6.5 GR, the .308 has 52% more KE and 48% more linear momentum at 300 yards.

Compared to the 6 ARC, the .308 has 53% more KE and 61% more linear momentum at 300 yards.

And none of that tells you anything about how much tissue will be damaged, or how well any of them will kill.

 

[Carpet Capital Shyster]

I quit packing the AR10 cause it was a pig. My SFAR is less piggy and will go hunting.

It’s my favorite rifle right now. My 6.5 PRC, my 270, and my BLR never leave the safe these days.

 

[Rotnguns]

And none of that tells you anything about how much tissue will be damaged, or how well any of them will kill.

Actually, most modern terminal ballistics models use some combination of kinetic energy and momentum, along with bullet shape and stability. They may not call out momentum directly, but since their models often use both kinetic energy and velocity as variables, momentum does play a role because it is proportional to velocity. Indeed, General Hatcher's formula, used for many years to characterize terminal ballistics, directly employed linear momentum:

Measuring Effectiveness of Cartridges: Hatcher Formula

In our last two posts, we studied a couple of empirical formulae that were proposed by big-game hunters, the Taylor KO Factor by John "Pond...

firearmshistory.blogspot.com

 

[ResearchinStuff]

of course momentum and KE are real. but, when you start comparing the size of the wounds made by different bullets (best done with gel tests), what very quickly becomes apparent is that neither momentum nor KE are correlated to the volume of the wound. Instead, the wound volume is correlated to bullet construction and impact velocity.

The older, simpler theories about what is happening in terminal ballistics have been thoroughly and rigorously debunked by the FBI and ammo companies via testing.

Lots of test data to look at here: https://www.hornadyle.com/

 

[Rotnguns]

of course momentum and KE are real. but, when you start comparing the size of the wounds made by different bullets (best done with gel tests), what very quickly becomes apparent is that neither momentum nor KE are correlated to the volume of the wound. Instead, the wound volume is correlated to bullet construction and impact velocity.

The older, simpler theories about what is happening in terminal ballistics have been thoroughly and rigorously debunked by the FBI and ammo companies via testing.

Lots of test data to look at here: https://www.hornadyle.com/

Thanks for the thoughtful reply and I am enjoying this thread. I would point out that gel models are not particularly good indicators of terminal ballistics in warm-blooded creatures and humans. In particular, the viscoelastic properties of ballistic gelatin poorly reflect the anisotropic nature of human or animal soft tissue. And of course, homogenous and isotropic material of any type cannot be used as a proxy for bone. Really, the best source of data, uncomfortable as it is to say, is empirical evidence from careful measurements of actual wound channels. But that's seriously compromised by unknown variables such as range, angle of impact, external clothing, etc.

 

[ResearchinStuff]

Calibrated ballistics gelatin is intended and calibrated to provide representative results. Again, lots of work done by the fbi to figure this out and develop a repeatable testing material. They're very interested in being able to kill people.