6.5br Hybrid Build

[Mram10us]

Got the new barrel chambered with the 6.5 whatever and it turned out great headspace wise. Fire formed some 6br brass with 130 hybrids and 22-28gr Varget. You can see in the pic how 26-28 seem to fully ff the brass. I'll load them all up with 28 and test groups

 

[MNbogboy]

I like it. The "6bMram"!

 

[can1010]

Got the new barrel chambered with the 6.5 whatever and it turned out great headspace wise. Fire formed some 6br brass with 130 hybrids and 22-28gr Varget. You can see in the pic how 26-28 seem to fully ff the brass. I'll load them all up with 28 and test groups
View attachment 181619

I like it. that is a lot of extra expansion in the web and I know others used 8x68 brass in 375 ruger chambers causing the extra expansion but don't think anybody did any extensive testing to see how it holds up. it will be interesting to see your outcome. I do like the simplicity and low cost of your ideas keep them coming.

 

[Mram10us]

Thanks guys. Nice to know the time posting is worth it. Here she is all mounted up on the tc compass. The other 3 barrels I made for the tcc have brakes so I made this pseudo brake from a chunk of barrel I had from an old 284. No side ports since they aren't needed, but 2 holes on top to help with muzzle jump. We'll see how it works

 

[Farmerboy78]

Curious if you have thought about the Sierra tmk 107gr. It's nearly as long as a 123gr eld to the eye and should jump your velocity drastically. Just for comparison, I used them in a 6.5 creedmoor. With a 140gr, you normally get 2750-2800fps. With a 120-123gr you normally get 2900ush. With the 107gr, I had amazing accuracy, lower powder charge to meet the 3200fps prs speed limit. Was getting 3112fps and was 3-4gr under max with varget. Might be worth a try.

 

[Mram10us]

Curious if you have thought about the Sierra tmk 107gr. It's nearly as long as a 123gr eld to the eye and should jump your velocity drastically. Just for comparison, I used them in a 6.5 creedmoor. With a 140gr, you normally get 2750-2800fps. With a 120-123gr you normally get 2900ush. With the 107gr, I had amazing accuracy, lower powder charge to meet the 3200fps prs speed limit. Was getting 3112fps and was 3-4gr under max with varget. Might be worth a try.

I havent thought of load data at all, to be honest. I'm ignorant to this hybrid so far and will take any advice you have. Now I have to get more bullets

 

[Farmerboy78]

I havent thought of load data at all, to be honest. I'm ignorant to this hybrid so far and will take any advice you have. Now I have to get more bullets

Its a great round and should let it perform!

 

[MNbogboy]

Curious if you have thought about the Sierra tmk 107gr. It's nearly as long as a 123gr eld to the eye and should jump your velocity drastically. Just for comparison, I used them in a 6.5 creedmoor. With a 140gr, you normally get 2750-2800fps. With a 120-123gr you normally get 2900ush. With the 107gr, I had amazing accuracy, lower powder charge to meet the 3200fps prs speed limit. Was getting 3112fps and was 3-4gr under max with varget. Might be worth a try.

I should apologize for hi-jacking this thread, I answered a question from another member and I think it got mixed in with Mram10us thread.
The two cases are similar in a photo.
Sorry for creating confusion.

 

[Mram10us]

All good!

 

[Mram10us]

Before and after full fireforming
Left is 6.5mmBR, right is 6.5whatever

 

[MNbogboy]

Before and after full fireforming
Left is 6.5mmBR, right is 6.5whatever
View attachment 181884

A couple of things, I didn't do the math on your chamber diameter fit yet, so correct me if I'm way off base.

First is, and I think you mentioned it earlier, that there is a lot of "stretch" at the web. I think I see that in the picture. Is it possible for you to section a case lengthwise (mill/hacksaw) to get a clearer picture of what's going on in there? We would not want to see any partial fractures which could possibly lead to case failure.

Second, now without doing the math again it may be possible to use 6.5x55 Swede brass to avoid the case head expansion.

Interesting project.

 

[MNbogboy]

Preliminary numbers are saying in theory you are stretching about .017/.018. Using formed Swede brass should cut that down to .010/.011. An even shorter chamber (.175 shorter) would make the Swede brass work perfect at the web.
That would be the "mini-mini 6.5/284/6brMram10us" a 1.382 long case!

 

[Mram10us]

A couple of things, I didn't do the math on your chamber diameter fit yet, so correct me if I'm way off base.

First is, and I think you mentioned it earlier, that there is a lot of "stretch" at the web. I think I see that in the picture. Is it possible for you to section a case lengthwise (mill/hacksaw) to get a clearer picture of what's going on in there? We would not want to see any partial fractures which could possibly lead to case failure.

Second, now without doing the math again it may be possible to use 6.5x55 Swede brass to avoid the case head expansion.

Interesting project.

It is a lot of stretch, but it's working so far. 30 rounds and no lines. Yes, .017" ish is about right. My goal was to maximize the 6br brass to where it turned out to be a 6.5 dasher type. So far it's working. Next range session will tell us more

 

[Mram10us]

Preliminary numbers are saying in theory you are stretching about .017/.018. Using formed Swede brass should cut that down to .010/.011. An even shorter chamber (.175 shorter) would make the Swede brass work perfect at the web.
That would be the "mini-mini 6.5/284/6brMram10us" a 1.382 long case!

I don't want to cut down the stretch, because I'm trying to maximize the cartridge and brass. 6.5 Creedmoor reamer was another idea, but I wanted the sphere/ball/ fatty cartridge. Almost like a 243wssm, but use on a std short action