New High Velocity .308 30 XCB testing

[waco]

So I'm at it again. Same bullet, same rifle, only this time I'm testing H414
The Remington 700 got a new paint job but other than that she is still the same rifle as last time.
Today while running tests with my 1894 Marlin in .357 I also did a 10 shot Satterle ladder test.

This method of creating an accurate round has worked every time my brother and I have tried it. I am a firm believer in this load development process.
The bullets used in this test were cast by me about nine months ago. Lamar suggested I use an alloy of 90/6/4 (Pb/Sb/Sn) water dropped from the mold for a BHN of around 18-19 bhn. My previous loads were assembled using 40.0gr Rx15 for a MV of approximately 2480fps.

This new test loaded the same 165gr bullet with .2gr increment charges of H414 starting with 46.0gr and ending with 47.8gr
I am looking for flat spots in velocity were an accuracy node is likely to be. Here are the results. These numbers where obtained using a Magnetospeed chronograph.
46.0-2533
46.2-2573
46.4-2554
46.6-2559
46.8-2574
47.0-2582
47.2-2597
47.4-2609
47.6-2595
47.8-2621
Note there is only 5fps difference between loads three and four. This is the "flat spot" you are looking for. Next up I'll load a batch probably 46.5gr and shoot for groups at 100 yrds.
My last attempt at 500 yards with this bullet was only doing just over 2200fps. The additional 300fps will help the bullet stay supersonic until it reaches the target. Bullets falling into transonic stage from supersonic tend to do strange and unpredictable things. This has been my observation anyway.

So. Stay tuned for an upcoming video revisiting the 500 yard shoot. If you don't already know, We have a YouTube channel an we are
Coats Brothers Firearms.
Please check us out. We would love to have you as a new subscriber to our channel. Thanks.

 

[Brad]

And their videos are very well done.
Good content, good explanations, and excellent editing.

 

[Ian]

Yep, love the vids Walter, good stuff.

 

[waco]

Thank you guys.

 

[fiver]

looks like maybe another one at 47.5 too.
for a short barrel your finally getting some speed out of the thing.

 

[Ian]

H414 makes a lot of gas in a .308. It's also very responsive to ignition tweaks like crimp, jump, bullet weight, and buffer.

 

[Intheshop]

Nice write up Waco.

IME,and can't fully put it into words.... each rig can have serious likes N dislikes on how they respond to handling. What we get away with shooting JB's technique wise,isn't a guarantee shooting cast at higher velocity. It takes way more concentrating.Small things like a hiccup in bedding,scew torque,ANY issue with optics.... all seem to show up more with cast. I'll even go so far as to say as the barrel heats up with strings of fire..... CB's aren't as tolerant as JB's. Less lube helps. And don't be afraid of running different size bullets.... meaning, leaving the body as cast and just sizing the very bottom GC area..... also playing with nose size/shape.

Keep up the great work..... BW

 

[waco]

looks like maybe another one at 47.5 too.
for a short barrel your finally getting some speed out of the thing.

Yeah. I'd be happy to keep these under 2moa for a 10 shot group. I might test them on paper at 200 before shooting steel at 500

 

[waco]

Okay. Loaded up 40 rounds today. 20 @ 46.5gr and 20@ 47.5gr H414
They should give a MV of 2560-2600fps.
Hope is to test on paper at 200 yards in the next week or so.

 

[35 shooter]

I’ll be watching your results closely. H414 was fantastic with jacketed in a 7/08 I used to have. I do have 760 on hand and have meant to try it in my .308 with the xcb bullet, but haven’t yet.

Good luck with the 414.

 

[Ian]

6 through 7mm in cases like the .308 down to 7x57 and 6.5x55 seem to really like H414.

 

[fiver]

it has a very high velocity potential in the standard 7x57 at reasonable pressures too.

when I gave it a run in the 308 under jacketed bullets I was pretty much scooping a sized case full and leveling it off, then gently squeezing the bullet down in a neck with .005 worth of tension to keep everything together.

 

[freebullet]

Nice work, keep at it.