The 7.2 Greedmore initial virginal tests.

[Fuj]

Been working on this for the past several months for the 2025 season.
For you Creedmoor fellas, don't get your knickers in a twist. I'll just be
calling it a 7.2 anyways. It's a 284 Winchester case I shortened to 6.5
Creedmoor length and still keeps the 35 degree shoulder of the .284.
Barrel is a 6 groove, 12 twister Hart at 30" and no tuner at this time.
Just starting with some 100 gr Sierra varmints and N-135 powder. Bolt
lift got a little hard way quicker then expected so will back it off one full
grain and work back up to the 42 grain load 2 tenths at a time. Here's
the case and bore sighter target from yesterday. Had to set up at 90 yards.
because of the deep mud and water on the range......Going to be a fun one
to play with.......

 

[Ranger188]

Nice, been waiting to see how this turned out.

 

[Fuj]

For what it's worth, It's another one of my brewed up chassis rifles
with a Savage PTA. The past few years, I have been shouldering my
barrels. Well I went back to a nut just for this build. Barrels International
Has a much larger nut I ordered in to do some special fitting, on a 1.25"
barrel. Standard Savage barrel is straight. My larger diameter barrels if
using a not, I cut two steps. One for the larger barrel shoulder, and one
for the lead on the nut itself. Stock wrench will not fit over the new barrel
so I did a little clearance work in that respect. I'll be back out to the range
in a day or two once this crazy wind dies down and get a pic or two.

New style nut, and the smaller stock nut with a basic chamber cast. I should
have heated the barrel itself more. The casting looks like crap, but gave me
the numbers I was looking for.

 

[Fuj]

Had a good morning for the N-135 powder workup.....
I'm 3 ounces over the 22lb limit......Still at 90 yards because
of range conditions.

 

[Fuj]

Last visit to the range for a while. I dropped down 1/10th gr to
see either side of a few. Last group was simply bad manners. I'll
wait until our weather stabilizes better before I get into any seating
depth work. In the meantime, I have another but shorter 12 twister
that Stan Taylor had a 4 groove blank done for me several years back.
Might as well chamber it up for this same cat, for a back up......Nice to
be ahead of schedule for a change.......

 

[Sandstorm]

Lookin good Fuj......thats zippin right along too.

 

[Fuj]

That 30 inch Hart barrel is helping that out. This bullet, I will stay with
the N-135 powder and just get the seating depth test done. No reason
to chase any other powder. It's giving me a good fill. 90% keeps me in
a good node, and in the mid 3300's.......I still have two more bullets to
test in the 120 grain range, but these will be of a different nature. I'm
running short, tangent ogive bullets with only a .060" throat, and a tight
no turn.

 

[CJ6]

How thick are the necks if you're not turning them?

 

[Fuj]

Neck walls are .016". I cut the chamber by short stepping a .284
Whitley reamer I bought off of Danny Biggs, That reamer is a .013.
I then reamed the neck in a second operation to give me a clearance
of .0015 per side......Virtually no soot on the case necks.

 

[Sandstorm]

That's a tight seal you got there...Ive always heard folks like .006 or .003 a side.
However this is one area i have not thoroughly tested as I dont have a Lathe or easy access to my chamber
and neck area in general...interesting thought. hmmmm
I do not turn my necks anymore either when I can get away with it and have .006 on my latest few chambers,
and they shoot really well...easy cleans @ 600 on a good day.

 

[Fuj]

I was looking at the math of the neck for expansion and
release of the bullet. It's as close as I wanted to get. On
another note, I had a case that felt slightly harder to chamber.
It was simply a case I missed during the O.D. deburring process.
A very good anneal is your friend to keep that soot off the necks.

 

[Fuj]

A little update......Had a frantic last 2 days with weather around here.
Sunny, 70 degrees, and no wind. Flags were limp. First match at
Anderson creek is just over a week away, and up until this point it's
been raining with over 20 mph winds gusting over 40 mph......Load
I'm going with is the 100gr Sierra Varmint, at 3368 fps avg. For what
it's worth, seating depth tests were interesting with components used.
With the .060 free bore, this little flat based bullet did not like any kind
of jam. I backed off to .004" below touch, and it came together. I then
shot these. I made a correction but but went too much.......First match
of the year is just over a week away. If Jeff Gates and Jeremiah Keefe
don't show up, I should do well......LOL

 

[boltfluter]

Those are some very serious looking bag riders you have there! Very nice. That's a tac driver for sure. Good luck with your first match.
Paul

 

[ebb]

Since it's so much bigger in diameter than the Creedmoor, maybe a new name. I think the 7.2 Kardashian would be appropriate.

 

[Keefe300]

Fuj

Glad to see you got this cat up and running, I will be interested to see how it does at the match. I hope to get some testing in this Sunday. Been playing with a 6PPC using the Alpha brass.

 

[Fuj]

Fuj

Glad to see you got this cat up and running, I will be interested to see how it does at the match. I hope to get some testing in this Sunday. Been playing with a 6PPC using the Alpha brass.

I have one more window for another session and that would be Monday,
then it all goes down hill again. Hoping for decent weather at AC for next
Saturday. I really don't want to shoot on them indoor benches. Other then
that, I will get started on the 300 yard/meter work. Found another supply
of my favored but discontinued 130 Sierra. And I need to pull the March
and put the NF-Comp on it. I'm a bit way over 22 lbs. I have a couple of
tuners lying around but i need to get more weight off, and don't plan to
shorten the barrel to do it.......Good luck with the PPC. You should have
plenty of N-133. That N-135 for what I'm doing with light bullets on a fat
case is amazing stuff.

 

[CamoWhamo]

I had a similar idea a few years back and went so far as modifying some dies to make the brass but never got as far as chambering the rifle.
My design basically shortened the case by .225".
My idea was to use the 162gn projectiles seated just ahead of any potential donut and still be under the OAL to fit and feed through an AICS magazine.

I named it the .284 Vixen which was a nod to the parent cartridge and the "Vixen" is one of Santa's reindeer, alongside Dasher.

I still have the brass and dies and a take-off barrel that I was going to use as the proof of concept so maybe one day I'll get around to it.

 

[Fuj]

Yours would have been close to my SA284 I have shot for the past
several years. When I made it, it was primarily meant to work better
in a short action and load longer bullets for the magazine. I then went
and created the 284-ELF for the real light 130gr bullets. The 7.2 is an
exercise to run bullets down around 100gr or less with very little free
bore. The SA284 centered, I was pushing (single shot) the 183 Sierra
to 2850 fps In a 30", 8.5 twist Brux.

 

[CamoWhamo]

2850fps with the 183gr is cooking it. In My full size .284W with the same bullet that's about a max load as it's blowing out the primer pockets at 2900fps.

GRT is predicting I could expect somewhere around 2850fps with the 162gr in my shortened case.

What brass are you using?. I found Norma brass is the only brand that I can reliably push the shoulder back without any crumpling. Unfortunately my experience with Norma in the full size .284 is that the primer pockets will expand after only 2 reloads.

 

[Fuj]

The early cat's were all Norma brass. The SA284, I shot 5 times, then used
that brass to cat the ELF. My initial SA284 run was with a lot of 500 cases
2 years later, I did another lot of 500 cases. I really did not lose as many
primer pockets as expected, but the ones I used for the ELF, I was only
getting 3 more loading's. All in all with what I was doing, life expectancy
of the pockets was 7 to 8 loadings with a few less. All my work now is
on Peterson brass......What is your case length compared to my SA284 ??
Mine was at 2.0215" close to .308 Win length with 35 degree shoulder
further forward of the .308's giving it a shorter neck. I was also running a
.240 free bore to keep the bullet above the donut region. 4451 let me run
em' up there a bit and better then H-4350 and that included accuracy.
Ramshot Hunter let me go even more, but no accuracy. I wanted to use
H-4831-SC but case fill was terrible to get any speed I was looking for.

Shot the new 7.2 yesterday at the 100 yard UBR shoot at Anderson Creek.
Did'nt do bad , did'nt do good. Varmint bullets are not bench rest bullets, and
these have frequent flyer nines. I had at least two nines per target, but the
concept is there......It's going to keep me busy.