Sherman SWC 7mm

[Suther]

Don't the Sherman cartridges basically all have a reputation for only meeting stated ballistics with much higher pressure than you'd typically be looking to run? This certainly isn't the first discussion I've seen about Sherman cartridges and it always seems to boil down to that...

I see one of the comments ran the data through a ballistics program to come up with 92k. That's not actual testing though. - dan

Exactly the sort of thing I seem to see every time someone starts talking about Sherman ballistics...

 

[coleman1495]

I see one of the comments ran the data through a ballistics program to come up with 92k. That's not actual testing though. - dan

Shouldn’t Sherman Wildcats be releasing the pressure data? They must have a Pressure Trace or similar apparatus.
2720fps with a 190gn using 41gn of Varget is beyond incredible. In fact that would make it the most efficient cartridge ever produced by a huge margin. That would mean it produces significantly higher energy than even Sig’s fancy hybrid 3 piece cartridge.

 

[Suther]

Shouldn’t Sherman Wildcats be releasing the pressure data?

Why on earth would they want to tell everyone that their ballistics are only achievable with pressures well beyond 65k?

 

[coleman1495]

Why on earth would they want to tell everyone that their ballistics are only achievable with pressures well beyond 65k?

Honestly I think 65k psi is pretty generous. I bet it’s a good bit north of that.

Maybe when they say “@pressure” they mean catastrophic case failure lol.

 

[dan belisle]

Well, only one way to find out for sure, I guess. - dan

 

[Suther]

Honestly I think 65k psi is pretty generous. I bet it’s a good bit north of that.

Maybe when they say “@pressure” they mean catastrophic case failure lol.

Thats what I mean, 65k is the ballpark of the upper end of SAAMI max pressures for a lot of common stuff - 270win is 65k, 300 win mag is 64k, 7PRC is 65k etc. but to get the kind of ballistics Sherman claims I can only imagine you have got to be pushing it way past that.

 

[adamg]

I think the best comparable data we have - admittedly it is only calculated pressure from an application with actual chronograph data to back it up - is from the below video. In it, the comparable data points are:

215gr in .308win case
43gr 2526fps 76k psi
45gr 2614fps 89k psi

I'm going to put the over-under on the "@pressure" pressure being 95k psi.

180 Hybrids 340 G7
43gn varget 2825 @pressure
41gn varget 2720 great results

190 Atips 418G7
41.5gn varget 2750 @pressure
40gn varget 2630 happy

 

[adamg]

Having said all this, I would enjoy seeing the reamer print on this new chamber.

 

[dan belisle]

Having said all this, I would enjoy seeing the reamer print on this new chamber.

I'm looking for one now. If I find it, I'll post it. - dan

 

[jordanlillico]

Just shoot the 6.5x47l and 153.5s at sammi preaser or lower

hipresser is not the way to go

 

[adamg]

Just shoot the 6.5x47l and 153.5s at sammi preaser or lower

hipresser is not the way to go

Having spent all of 2024 shooting a 6.5x47L with 153.5 in a 26" barrel, I can tell you that 2620fps is a warm load.

 

[jordanlillico]

Then shoot 2580 area amd call it a day lol

 

[Ryan_mcle]

I was talking Derrick, who helped design this cartridge when I was down in Arkansas. They gained the case capacity by taking almost all the body taper out and blowing the shoulder forward and steeper. If I recall correctly they are seeing great performances with 555. He recieved his first lot of test brass last week so I expect components will be available this winter. I have a barrel on order and will get the reamer and dies sorted out next. Here is a picture of the brass. I will see if I can get a reamer print as well.