20 br load development

[Piglet]

So I put together a 9 twist 20 br a year ago. Have been back and forth w load development. I'm using norma brass, berger 55s, 7.5 remington primers, & a2520. I've worked up to 29.8 gr of powder and not seen velocity over 3500. So my question is where do I want to be velocity wise? Barrel is 28" I think. I just got a decent chronograph this spring. Shot a .198 group today @ 29.6gr w Ave velocity of 3463. Es and SD were not great. Es was 85, and SD was 35.5. I have read on here most guys seem to want to be around 3600 or a little more. Should I keep feeding it more powder or switch to something faster? Barrel life is a concern knowing that it's a short life w this clambering. I'd like to get there soon. Thanks for any help

 

[L.Sherm]

If its shooting were you want I'd stop there with a BR case.
When you start getting into upper 3600 and beyond your getting into 20BRA territory.
RL15 might get you more speed its definitely the 20BRA go to powder.

 

[Tommie]

Have you tried a slower burn rate powder?

 

[Piglet]

If its shooting were you want I'd stop there with a BR case.
When you start getting into upper 3600 and beyond your getting into 20BRA territory.
RL15 might get you more speed its definitely the 20BRA go

Have you tried a slower burn rate powder?

No. I have not, I had it in my head I would want a faster burn to get more fps. Will slower burn get me more fps? You'll have to pardon my ignorance I'm Slightly green on precision loading. But want to understand more.

 

[Tommie]

No. I have not, I had it in my head I would want a faster burn to get more fps. Will slower burn get me more fps? You'll have to pardon my ignorance I'm Slightly green on precision loading. But want to understand more.

Ok I’m just trying to help. Please understand zero offense is intended.
You’re loading a (somewhat) advanced wildcat cartridge combo which has precious little lab-tested load recipes. Not a “beginner” cartridge. What gives me a bit of concern is your statement about using fast powder to attain higher velocity. It kinda doesn’t always work that way and without some real knowledge/experience in the field of internal ballistics I’m worried you could find yourself in a sticky situation.
Once again my intent is not to hurt feelings.

 

[L.Sherm]

I tried RL16 and H4350 in my 20BRA and no matter how much powder I put to it it wouldn't go any faster than 3550 with the 55's. I'm not sure a much slower powder is your answer for more speed. If it was me I would try RL15.
Don't worry about E.S. or S.D let the target speak for accuracy, as long as your no higher than about 25 E.S and it shoots good thats all that matters.
AA2520 is real close to RL15 in burnrate when I tested the 2 in my 20PPCAI, but that doesn't mean 2520 is " the" powder for the BR case in a 20 cal.

 

[RegionRat]

Don't worry about E.S. or S.D let the target speak for accuracy, as long as your no higher than about 25 E.S and it shoots good thats all that matters.

Did you mean SD or ES?
Because an ES of 25 would be pretty high class.

I have read on here most guys seem to want to be around 3600 or a little more.

The 20 cal 55 grain Berger would need to be doing roughly 3600 fps or better in order to exceed the ballistic performance of the other common bullets like the Sierra 39 or Hornady 40 at their typical/practical speeds.

You can certainly shoot it slower if you want to, it isn't like there are any rules against shooting it slower.
A 204 Ruger cannot get this bullet to 3600 fps at allowable pressure for example.

It generally takes at least a BRA or Dasher sized capacity to get this 55 grain Berger up to those speeds with something like Varget. I have no opinion on the BR version as I have never tried it, I am sure someone will come along who knows more.

 

[B23]

Other then squaring the shoulder off to 40° instead of 30° the regular BR case has that's the only thing different about a BRA isn't it and with the BR case already pretty straight and all you're doing is squaring it off, not pushing it forward at all like they do with the Dasher, the case capacity increase from regular BR to BRA has to be, very, minimal at best. I recall reading something Alex Wheeler wrote about how the BRA was created to keep the case capacity and neck length basically the same as the regular BR but with a 40° shoulder angle and It was intentionally designed that way so it wouldn't gain case capacity.

So if a BRA has essentially the same case capacity as a BR but the BRA is getting more velocity, especially if it's a lot more, it's only because you're running the BRA at higher or considerably higher pressure, isn't it?

 

[17VLD]

That's a nice group Piglet. I'm curious who made that barrel. If the SD and ES is really bothering you I'd weigh your cases and try a group of five of the closest and see how they do. Or I might beg,borrow, or steal 5 Lapua pieces of gold and see what they do. I'd also try vv140 or vv150, the burn temp is low and the burn rate will be where you want to be. Also try cci450s. Are you hunting varmints or just targets?
Matt

 

[L.Sherm]

Did you mean SD or ES?
Because an ES of 25 would be pretty high class

 

[L.Sherm]

The 28 Nos is 23 E.S, the 6.5x06AI is 18.
Targets dont lie, these are not 1 hit wonders either.

 

[L.Sherm]

I've found just like Alex has mentioned few times on here E.S. has no correlation to vertical at the distances I shoot.

 

[7315br]

So I put together a 9 twist 20 br a year ago. Have been back and forth w load development. I'm using norma brass, berger 55s, 7.5 remington primers, & a2520. I've worked up to 29.8 gr of powder and not seen velocity over 3500. So my question is where do I want to be velocity wise? Barrel is 28" I think. I just got a decent chronograph this spring. Shot a .198 group today @ 29.6gr w Ave velocity of 3463. Es and SD were not great. Es was 85, and SD was 35.5. I have read on here most guys seem to want to be around 3600 or a little more. Should I keep feeding it more powder or switch to something faster? Barrel life is a concern knowing that it's a short life w this clambering. I'd like to get there soon. Thanks for any help

AFWIW (which "ain't" much)! After several 20BR's over a dozen years or more I settled long ago on 9-twist Bartlein or Krieger bbls, RL-15 powder , Lapua brass, and 55gr Bergers. Many groups in the 1's and occassionaly a "ought" group. I did like the CCI 450's slightly better than the Rem 7 1/2's. Velocity around 3640 fps.
As usual Sherm"s comments are "on the money"! Listen to his advice.

Best of luck.

 

[L.Sherm]

So if a BRA has essentially the same case capacity as a BR but the BRA is getting more velocity, especially if it's a lot more, it's only because you're running the BRA at higher or considerably higher pressure, isn't it?

Don't know the difference between BR and BRA case capacity never measured it didnt see any need, all I know is a BR case WILL NOT run with a BRA case in a 20 cal and I doudt will in a 6 either.
A BRA case will run 3735 easily with a 55

 

[B23]

Don't know the difference between BR and BRA case capacity never measured it didnt see any need, all I know is a BR case WILL NOT run with a BRA case in a 20 cal and I doudt will in a 6 either.
A BRA case will run 3735 easily with a 55

You mean it won't run with it at equal pressure because the case capacity in both is nearly the same the only real difference is the BRA has a 40° shoulder but that also hides pressure which allows you to stand on the gas harder without getting the more obvious signs of high pressure like harder bolt lift, clickers or ejector marks but that certainly doesn't mean higher chamber pressure is present.

 

[L.Sherm]

Its whatever you wanna believe.

 

[RegionRat]

Don't know the difference between BR and BRA case capacity never measured it didnt see any need, all I know is a BR case WILL NOT run with a BRA case in a 20 cal and I doudt will in a 6 either.
A BRA case will run 3735 easily with a 55

That would be a nice way to run if it isn't beating up the brass.
I've been running short on Lapua 6 BR brass (till just the other day) and went to a bigger case to play with the 55s.
The cases like the 22-250, 22 Creedmoor, etc., took me into H4350, H4831, etc.. I'll drop down to the 22 GT for the next one just to get that out of my system.

Were you using something in the RE-15 or Varget range in the BRA, or was it something else?

 

[L.Sherm]

Why is it about 12 years ago I took a 280 Rem had it rechambered to a 280AI using same barrel, same action, same bullets, same Rem brass just fireformed and I gained 240 FPS.
Theres something to some cases being AI besides hiding pressure. Some actions, barrels and brass handle pressure different ly just like powders are faster vrs others i believe its a combination of efficiency.
My 20PPCAI is another example it will run over 4,000FPS with 39-40 bullets

 

[L.Sherm]

That would be a nice way to run if it isn't beating up the brass.

It is by far beating up brass, I know some who have been knocking on 3850fps I just run mine there because it shoots so well.

 

[L.Sherm]

Just for giggles I measured a 20BRA case with water, to the nk - shoulder junction its 33.68, 37.57 to the top of the case. This is with blue box necked down Lapua 6 BR brass.
If I had to guess about 1.5 gr H2O difference.
Damn check my math and readjusted, holy$hit need to work with numbers more lol.