6.5br Hybrid Build

[Mram10us]

I can't help but try different wildcats, so today I decided to find a use for some 6br and 7br brass that I have around. I have 6br and 30br reamers that are proven, but I had to make it difficult.

Why?
Absolutely love what a 6br can do and I wanted to find a 6.5 that might compare. I also wanted to test the theory of "a sphere is the most efficient way to burn powder". Since I dont know how to chamber a sphere yet, I decided to make this as short and fat as the action would allow. The shoulder has been bumped out to 35degrees and the entire case has had the circumference increased by and avg of .017". This increased the volume by ~8% which should help in equaling the 6br performance.

Chambering:
I used a 6.5-284 reamer and pushed it in enough to have the 6br go gauge fit with a bit of crush (.0015-.002").
Edit: after realizing the neck was longer on the 6br, I ran in the reamer enough to have a slight crush on the neck when trimmed to 1.545". Gives more breathing room and no wasted neck

Brass:
I used Lapua 6br brass. Luckily it is nice and thick because I am pushing the limits of case stretch. Two cases were tested but didn't fully fireform. I play with it more tomorrow and perfect the method. Had lots of practice

Dies:
Here is where it pains me to say, but I have to chop a 6.5-284 fl sizing die. I have plenty of universal seating dies that will work just fine.

Summary:
I made up a fire form setup from an old barrel. Threaded 3" of it and made a remage nut type setup to easily adjust headspace. If the fire forming works out, I'll chamber a real barrel and add it to the Thompson center compass arsenal for further testing. Any advice is welcome!!!

 

[Jud96]

You should have just built a 6mm Dasher or just do a 243 WSSM and use a proper reamer for either one.

 

[Mram10us]

You should have just built a 6mm Dasher or just do a 243 WSSM and use a proper reamer for either one.

Why? A 6 dasher is a 6mm. I wanted a 6.5. A 243wssm is a 6mm. I wanted a 6.5. sheesh

 

[can1010]

sounds like you are working off the 7mm pussycat idea posted in your other thread.
I have made up some drawings using the same ideas. I used the 284 case necked to 6mm with the neck/shoulder location of the 6GT and the neck length of the 6br. already formed some brass to get idea of case capacity. did drawnings for 6mm,6.5mm,and 30 cal. all with case length of 1.770 capacity ranged from 45.6-48.2 depending on cal. quickload predictions look promising especially the 30 with 155s and under. will watch for your results

 

[Mram10us]

sounds like you are working off the 7mm pussycat idea posted in your other thread.
I have made up some drawings using the same ideas. I used the 284 case necked to 6mm with the neck/shoulder location of the 6GT and the neck length of the 6br. already formed some brass to get idea of case capacity. did drawnings for 6mm,6.5mm,and 30 cal. all with case length of 1.770 capacity ranged from 45.6-48.2 depending on cal. quickload predictions look promising especially the 30 with 155s and under. will watch for your results

Great! How far are you on it. Neck is obviously longer on the 6br than the 6.5-284, so I'm plunging the reamer in another .030". I'll fireform some in the next hour and post pics. Like I tell my wife, if you don't hear from me in the next hour, just call 911

 

[can1010]

still playing with decision on shoulder angle. I am forming brass with win mag dies 338 down to 264 and made an extended stud to put in shellholder and push the case up into the die then brass rod to pop it back out of die. if forms them real easy and if I leave the 25 degree shoulder I don't need dies but still need a reamer, so many decisions. wish I knew how to get drawnings from quickdesign to here I am not very computer savey

 

[Mram10us]

I'm a sucker for the 35deg of the 6.5-284. Plus, easy to cut the die with a grinding wheel and touch up on the lathe. Tried fireforming with trail boss and a patch in the shop. Went from 5gr to 10gr with a patch in the top. COW is for eating not shooting No good luck. Need to load up some low charge stuff and just go crazy. Made my ff barrel from an old 7mm and it works ok for ff but don't have cheap 6.5 bullets. Back to the drawing board.... Ill load up 2 just to see what the final case will look like

 

[Mram10us]

Well, I'm going to just build a barrel and try it out. Brass seems to hold up to stout loads. Here is a comparison pic. 6br on the left and the 6.5 whatever hybrid on the right. It didn't fully fireform so I will post more pics when the new barrel is done and I've got some fully ff cases

 

[MNbogboy]

still playing with decision on shoulder angle. I am forming brass with win mag dies 338 down to 264 and made an extended stud to put in shellholder and push the case up into the die then brass rod to pop it back out of die. if forms them real easy and if I leave the 25 degree shoulder I don't need dies but still need a reamer, so many decisions. wish I knew how to get drawnings from quickdesign to here I am not very computer savey

That's exactly the way the 7 "pussycat" started. I wanted to see if I could form the brass first. I used a "pusher" and brass rod to extract.
Mram10us, I used a cutoff wheel to shorten the 7 mag dies, no problem. My sizing die however did not have enough thread left for a locknut when I was done. It now wears a sleeve with a set screw. Seater ended up fine. These were the cheapest dies I could find (used std rcbs of ebay) so not much lost if the project failed.

 

[MNbogboy]

Just getting back to it this past week, as we were above freezing a couple of days. Still struggling somewhat, this 7 shot string started with cold clean barrel. Same POA

3 in one pile last 4 up & right. This was only 100 yards.
Approaching 475 rounds so far. The 6.5-284 brass is tough. 10 fired on a few cases now and primer pockets on all 50 original Hornady cases are tight.
If this had started with a premium barrel instead of the Savage factory railroad track job it may have been a shooter with some of the bullet/powder combinations I have tried.

 

[MNbogboy]

Double picture, sorry

 

[Mram10us]

That's exactly the way the 7 "pussycat" started. I wanted to see if I could form the brass first. I used a "pusher" and brass rod to extract.
Mram10us, I used a cutoff wheel to shorten the 7 mag dies, no problem. My sizing die however did not have enough thread left for a locknut when I was done. It now wears a sleeve with a set screw. Seater ended up fine. These were the cheapest dies I could find (used std rcbs of ebay) so not much lost if the project failed.

I hadn't thought about there not being enough threads. I like the project. Off to the shop. Indicating the bore right now. Trying a different way this time. Gordy style to see if there is any difference.

 

[can1010]

MNbogboy that upper group looks promising. I have had savage barrels shift like that once they foul but seem to stabilize til the next cleaning. how are you doing with velocities, are you still using the 140 ballistic tip?
cutting down a die will make life alot easier but i dont want to deal with the case growth and trimming all the time and bringing the shoulder material in to the neck causing doughnut problems. how are your cases doing with growth?

 

[MNbogboy]

MNbogboy that upper group looks promising. I have had savage barrels shift like that once they foul but seem to stabilize til the next cleaning. how are you doing with velocities, are you still using the 140 ballistic tip?
cutting down a die will make life alot easier but i dont want to deal with the case growth and trimming all the time and bringing the shoulder material in to the neck causing doughnut problems. how are your cases doing with growth?

These were 139 gr Hornady soft points.
The 140 bts shot about the same .5 - .75.
Also am using some 120 V-max with some success. Imr4895 & varget with the 120s. In the 2900ish category. 139 & 140s with h4350 around 2750-2800. Case capacity ended up at 48.5 gr H2O. With trim length right at 1.750.
Cases had donuts for first couple of firings (inside reamed) but have been donut free since. I anneal & bump .002 every firing they only grow about .001 to .002 each firing also.