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JJ ROCK XL 375 CHEYTAC BARREL OPTIONS

Finally starting to buy the components and looking for some options.
All help is appreciated

Got my Mcmillan beast ordered today

John Hiller
 
What bullet do you want to shoot? That will determine the twist you want. Other than that, there are a lot of guys that can make you a barrel
 
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what do you recommend ? 400 cutting edge ?

The intent is to go far as possible, primarily 2 miles
 
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I put a Brux on order. The fastest twist they offer is a 10. Their price seemed to be reasonable
for a 36 inch 1.45 to 1.1 for 520. I am hoping on the a tips. Twist may be marginal for the heavy solids.
 
I wouldn’t go slower than 1-8. That’s what my next barrel is. I have to run the Badlands’s 350 icbm bullet because I have a 1-10 on my current barrel. The guys shooting 400 aren’t running away from me.

My next barrel is a 1.45 straight 33” 1-8 Krieger. It’s ready to go when my current one burns out
 
Ken at k&p barrels can make you any twist rate and barrel you want was running around 4 to 5 weeks delivered.
 
Great stock choice. The Beast has such a huge fore end that it will tend to dwarf barrels, unlike the older Big Mac design.

I built a .408 Cheytac on an “Urban Camo” Beast II with a very long, straight 2 inch diameter Krieger barrel that doesn’t need a muzzle brake, which is good for the ears. 2 inch next to a 1.25.

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... kind of a prone or almost benchrest set up that is not very handy or deployable. But with a single shot Bat this rifle was never going to much of a weapon.

You picked a great action as well from the one demo I have seen. My .375 is going to be better on steel which means this barrel my stay unfired for a while.
 
Finally starting to buy the components and looking for some options.
All help is appreciated

Got my Mcmillan beast ordered today

John Hiller

what do you recommend ? 400 cutting edge ?

The intent is to go far as possible, primarily 2 miles

I recommend that you decide if you're going to compete, then build to the requirements of the competition. KO2M has a definitive weight limit which cannot be exceeded. Other competitions maybe are not so restrictive. Check the weight of the components you want to use before purchasing. If you're having a hard time deciding, maybe check with your chosen gunsmith to get some advice. It can get real expensive to go ahead and buy components only to find that you're going to be overweight...:eek::mad:

If you want to shoot for your own pleasure then you build to your own desires.;)
 
As for the bullet choice question the Lehigh Defense 353 grain solid has a G1 over 1.0. That’s shocking to me because at that moderate weight, these could be fired at a very high velocity that gives them the highest effective BC basically in all of small arms, while still delivering visible impacts and misses.
 
Never really thought of weight. I guess the ultimate goal besides getting a 2 mile hit is to compete in king of 2 mile

Thanks for the heads up !
 
KO2M and all the other competitions for ELR have their respective rules so it's important to read those rules carefully.

KO2M weight limit is currently 40 lbs. (there are limits to what you can use in conjunction with the rifle)

KO2M+ (new) weight limit is 45 lbs. (there are limits to what you can use in conjunction with the rifle)

Check other competitions for limits.

The barrel is usually the greatest contributor of weight. Diameter, taper and groove diameter control this weight. As an extreme example using a calculator, a 2.0" diameter (no taper) barrel 36" in length with a .375" groove diameter will weigh somewhere around 30 lbs. in stainless steel.

My 1.35" straight .375 weighs about 13 lbs. Big difference!

Next you need to consider the rules for bipods, how to attach and the weight, of course.

I use a custom barrel block for any barrel 30" and over so I have to automatically include this weight into the total.
 
I’m not sure how accessible K2M is to enter. I had the impression some time back that entry was extremely limited and not necessarily based just upon registration timing, use of suitable equipment, or other rifle discipline achievement.

In other words, even that pool was too large by multiples and required selection from looking at one’s other ELR events. I’d like to know more myself.
 
As for the bullet choice question the Lehigh Defense 353 grain solid has a G1 over 1.0. That’s shocking to me because at that moderate weight, these could be fired at a very high velocity that gives them the highest effective BC basically in all of small arms, while still delivering visible impacts and misses.
Have you or anyone you personally know, verified that bc?
 
Have you or anyone you personally know, verified that bc?


Yeah, I zeroed and ran a JBM trajectory chart in close intervals based on 600 yard shots before I took that rifle to Montana. Thanks to my friend’s Labradar, we trapped velocity at the muzzle and at the ShotMarker (610 yds).

With velocities measured at two known distances significantly far apart from each other, I used the method I have used in the past to calculate drop.

Using the manufacturer’s weight (not that it matters) BC (matters) and MV, as a starting point at my elevation, I run a trajectory and see how closely it resembles the Target velocity reported.

In this case, the match up was spot on. I shot into the prevalent headwind that day of about 10-15 FPS (typical match, possibly more as I shot quickly after a match at the patience of competitors) ShotMarker reported 2,383 average of 4 shots at 600 (610) although the Labrador picked up only three out of four shots. The Labradar showed an average of 2,986 at the muzzle.

If you run those numbers with the headwind factored in, the G1 BC will have to hover at 1.0+ to make the MV and 600 yard numbers match what was reported. That’s the same figure Lehigh claims.

That BC claimed by Lehigh comports with my range experience shooting fast, low drag 7mm’s with BC’s in the .7’s, plus. While I have gotten, for example, the very high BC 183 SMK to cross at over 2,400 FPS at the 600 target, it needed substantially higher MV to do so.


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