6mm BRA Load development

[Billiam1211]

Looking for a little advice on a 6mm BRA load development before I go ahead and start cranking out a match load. I built a 6 BRA on a LP Fuzion action with a 26" Rock Creek barrel. I'm currently using 107gr SMKs, Alpha Brass, 205M primers, and loading .020 off the lands. All shooting I've done so far has basically been done in 29-35 degree weather. In regard to use case, this is primarily a PRS match type rifle so my load doesn't need to be screaming fast. Just reliable, consistent, and 1/2 minute or better accuracy.

During the break-in process I loaded 30gr of H4895 which got me 2913 fps and shot unbelievably well as shown below. My only hesitation on this load is that I did see initial signs of pressure.

The primers show slight signs of pressure I was catching the ejector imprints on almost every case head. I was thinking that given I was in 30 degree weather, during the summer time this load would cause problems.

I decided to try doing a couple of the velocity node tests to find 'flat spots' and find pressure for both Varget and H4985. The odd thing here is Varget is way slower than I thought. Even at 29.8 grains, Varget was only producing 2789 fps and showing signs of slight pressure.

It seems like H4895 is the way to go for this barrel. 28.5gr / 2,800 fps is going to be the lower node, which performed very well in regards to accuracy however I was hoping to be around 2,850-2900 fps in velocity.

Given this data, what would you guys do:
- Load 28.5gr of H4895 and play it safe?
- Live dangerously and run 30gr of H4895 and figure it out later in the summer time when it warms up?
- Try again with Varget and see what happens if I push it a little harder?

 

[Cardboard Assassin]

How many rounds have you got down the barrel at this point? Barrels tend to get a little faster as they break in so that may help your situation.

Its unlikely given it sounds like it is a new barrel but if a carbon ring has developed then that could send you in a loop with pressure issues.

Food for thought.

 

[Billiam1211]

How many rounds have you got down the barrel at this point? Barrels tend to get a little faster as they break in so that may help your situation.

Its unlikely given it sounds like it is a new barrel but if a carbon ring has developed then that could send you in a loop with pressure issues.

Food for thought.

I’m 100 rounds in so doubt it’s a carbon ring at this point. I was thinking based on my last 5 barrels that 100 rounds would be good enough to start load development

 

[Feniks Technologies]

Ejector swipe and primer cratering can happen for other reasons than pressure.

Unless something is up with chamber or there’s oil/water in there…..you’re not going to be near the top end of pressure with 30gr of Varget.

 

[marchboom]

I would definitely do load testing in temps that are relatively close to what you will be shooting in for a match. Your testing described above is for cold weather. You would be surprised how much more pressure is developed when the temp goes up 30-40 degrees. Error on the side of safety.

 

[Cardboard Assassin]

Ejector swipe and primer cratering can happen for other reasons than pressure.

Unless something is up with chamber or there’s oil/water in there…..you’re not going to be near the top end of pressure with 30gr of Varget.

This ^^^^^ is accurate.

Pretty sure I had this issue recently after giving my rifle (6BR) a thorough cleaning (including the chamber). I suspect there was some leftover fluid still in the chamber when I sent the first few rounds downrange and I saw slight pressure signs.

After a couple of rounds everything settled down and the pressure signs went away.

 

[Billiam1211]

I got the same response on a FB group where I asked the same question. I’m guessing you guys are dead on. Everyone said to thoroughly clean the brass and chamber and try again. I’ll give that a shot for the next range trip.

 

[Matt_3479]

I would probably redo the varget ladder and see if you can ramp it up a little. You should be running too hot yet. Im working with n-140 and got up too 3000fps. It’s a hot hot load, but found a node in the 2870-2880 range and another 2920-2930 range but figured It might be a little hard on brass so starting with the 2880 node

 

[Billiam1211]

A 6BRA group I joined mentioned that everyone running Alpha 6BRA brass gets premature pressure signs on the case head. Guess I should be using the primers as a primary indicator of pressure. I’m planning to keep my H4895 load as is and probably work up a faster load with Varget.

 

[Changed]

If you could choose any velocity to shoot at what would that be?

Find the charge that gets that for you and do a quick seating depth test. Then shoot the hell outta it.

Stop worrying about nodes.

 

[Billiam1211]

If you could choose any velocity to shoot at what would that be?

Find the charge that gets that for you and do a quick seating depth test. Then shoot the hell outta it.

Stop worrying about nodes.

I wasn’t worried about hitting nodes, more so hitting pressure prematurely but I guess it’s just a common trend in Alpha brass that I wasn’t aware of.

 

[OREGUN]

I shoot Lapua brass, so there’s that. But 30 gns of H4895 pushing 105 hybrids .020 off the lands at 2905 fps has been my go to load for several barrels now. I shoot a lot at temps around 35-40 but have also shot matches at 85 with no issues. Any heavy bolt lift? Your primers dont look particularly flat or cratered. was this the first firing on the brass? Was there any lube left on the cases?

 

[inkballedtarget]

When I was doing my initial BRA load development I also had some heavy bolt lift with a relatively mild load at 2805 with 109s. I think my false pressure was coming from a dirty chamber (read sticky) caused by the sharpie I was using to number the cases I was testing. I’m not sure if this was the culprit, but with a clean chamber and not using the sharpie the heavy bolt lift went away.

Do you know if your chamber was cut for alpha brass or Lapua brass? Someone here will know better, but if it was cut for Lapua and Alpha is being used would that cause a pressure issue?

 

[gconnoyer]

2900 in a 26" BRA is way too fast. thats why you're seeing pressure.

Back it down to that 2800 "low" node. Thats about where a BRA should live.
It wont need constantly tweaked, will shoot great, and will be so much easier on brass and barrel.

 

[gconnoyer]

When I was doing my initial BRA load development I also had some heavy bolt lift with a relatively mild load at 2805 with 109s. I think my false pressure was coming from a dirty chamber (read sticky) caused by the sharpie I was using to number the cases I was testing. I’m not sure if this was the culprit, but with a clean chamber and not using the sharpie the heavy bolt lift went away.

Do you know if your chamber was cut for alpha brass or Lapua brass? Someone here will know better, but if it was cut for Lapua and Alpha is being used would that cause a pressure issue?

It wont really cause a pressure issue, but generally it wont be happy. Sticky bolt, not shooting well, etc.
The alpha necks are thicker than the lapua. I think most use a .274 neck for Alpha and .272 for Lapua.

 

[OREGUN]

I thought 2900 WAS the low node for 6BRA. The whole point of brA is to get to 2900-3000 (6dasher velocities) out of a 6BR case. Idealized efficiency for 105s, case shape for more pressure, no fireforming to screw up. If you are shooting at 2800, you might as well have stuck with 6BR.

30 ish grains of H4895 or 31.5 ish grains of Varget. No dasher fussy-ness, all (or more of) the dasher accuracy.

 

[inkballedtarget]

I thought 2900 WAS the low node for 6BRA. The whole point of brA is to get to 2900-3000 (6dasher velocities) out of a 6BR case. Idealized efficiency for 105s, case shape for more pressure, no fireforming to screw up. If you are shooting at 2800, you might as well have stuck with 6BR.

30 ish grains of H4895 or 31.5 ish grains of Varget. No dasher fussy-ness, all (or more of) the dasher accuracy.

I suppose I’m in the basement node for the brA, just because it can run that hot doesn’t mean it needs to. I’ve had a couple of BR barrels, but prefer the bra for a few reasons.

 

[OREGUN]

I suppose I’m in the basement node for the brA, just because it can run that hot doesn’t mean it needs to. I’ve had a couple of BR barrels, but prefer the bra for a few reasons.

I was mostly surprised by the idea the 2900 is “way too fast”.

 

[Lunchbox27]

2900 in a 26" BRA is way too fast. thats why you're seeing pressure.

Back it down to that 2800 "low" node. Thats about where a BRA should live.
It wont need constantly tweaked, will shoot great, and will be so much easier on brass and barrel.

What is the point of doing an Ackley over a 6BR then? I don’t run a BRA (only a BR) but my 105’s are at 2850 (26” barrel).

If what you’re saying is true, why go 6BRA? All those running ackely that I have seen are in the 2900-2950 range.

Your statement contradicts everything I have read on 6BRA.

 

[DellaDog]

2900 in a 26" BRA is way too fast. thats why you're seeing pressure.

No, it’s not.

I’d say it’s close to ideal. H4895 varies considerably from lot to lot, but both barrels I’ve shot like 2920 with 105s. To get there 4895 varies from 30.1 - 30.6 depending on lot. This is with Alpha OCD brass, which as mentioned takes less than Lapua.

Varget likes the same speed, but takes about a grain more to get there.

 

[Frank Green]

Something else to consider…

What is the actual bore and groove size of the barrel?

If you purchased a tight bore barrel…that will drive up pressures with the same load vs a standard bore size barrel.

What spec chamber reamer did you use as well. Another variable to consider.

Later, Frank
Bartlein Barrels

 

[Feniks Technologies]

Most people are over saami pressure (or what would be saami if it were approved) when it comes to BR cases.

Will it work in your rifle…..many times yes. But there are many factors. Bore size like Frank mentioned is one that is often times overlooked.

Get a little soft brass or some moisture/oil in chamber, or for some reason the barrel steel/chamber expands more…..and then you have issues.


The best way to get the speed many want from BR cases is a longer barrel.



Obviously Gordon’s and quickload aren’t gospel….but go mess around with them and you’ll likely find many are much closer to high pressure than we realize.

 

[Govt Mule]

2900 in a 26" BRA is way too fast. thats why you're seeing pressure.

Back it down to that 2800 "low" node. Thats about where a BRA should live.
It wont need constantly tweaked, will shoot great, and will be so much easier on brass and barrel.

^^^^^^^^^^ I have loads with both Varget and H4895. Depending on lot #'s, the 4895 load is 29.4 - 30.1 grains. Varget is 31.2 - 31.6 with Berger 108 BT's. That is out of a 30" barrel. Velocities are mid 2900's.
Is your barrel a .236 or .237 bore? Do you turn necks? Was this virgin brass? I always jam the bullet for the first firing at a reduced load from where there is a history of the powder charges working (lapua brass). The one guy I know that uses Alpha brass still lightly jammed the bullet on the first firing. High humidity on hot days can spike pressures that had the load developed in cool/cold temps as well. Ask me how I know You can't expect Dasher velocities from a BRA.

 

[Billiam1211]

To address a few of the comments, my barrel is a Patriot Valley Arms 26” Rock Creek cut rifled prefit for a LP Fuzion. The brass is new Alpha OCD brass as I’m working my way through the first firing. I don’t know which reamer spec Josh uses, but I’m sure I could ask.

Upon taking some advice from a few other guys, I found that my load is actually just fine. I put a piece of new brass that was fully prepped into the chamber and closed the bolt and found that just doing that was leaving the ejector imprint on the case head, this I was misreading my brass and there was no pressure signs at all.

A few guys mentioned that the ejector may need to be honed or will naturally smooth out over time and this will go away.

 

[mbeavers1]

I dont run a BRA, but why push it so hard? What do you gain? So....your elevation is .2-.3 less or windage at 1k is .2 less? Running at a lower pressure will reduce muzzle jump even more which will help see each impact which is infinitely more important than any slight ballistic gain. By the time you start running a BRA or a Dasher in the mid 2900s, you might as well run a 6Creed.

My .02 of course, but many top ranked (nationally) here in central TX are running BRAs and dashers in the mid 2800s. I run a 6BR at 2805. Exactly why I hit the easy button and went BR.

 

[Billiam1211]

I dont run a BRA, but why push it so hard? What do you gain? So....your elevation is .2-.3 less or windage at 1k is .2 less? Running at a lower pressure will reduce muzzle jump even more which will help see each impact which is infinitely more important than any slight ballistic gain. By the time you start running a BRA or a Dasher in the mid 2900s, you might as well run a 6Creed.

My .02 of course, but many top ranked (nationally) here in central TX are running BRAs and dashers in the mid 2800s. I run a 6BR at 2805. Exactly why I hit the easy button and went BR.

You’re dead on. I was just concerned because I though I was seeing pressure at 2,800 fps, which should be a super conservative velocity in BRA. I typically run a conservative load, just in this case I was reading my brass wrong. My intention was to be around 2,850 since most of my shooting is around 600 yards at matches with the occasional long bomb stage.

 

[mbeavers1]

You’re dead on. I was just concerned because I though I was seeing pressure at 2,800 fps, which should be a super conservative velocity in BRA. I typically run a conservative load, just in this case I was reading my brass wrong. My intention was to be around 2,850 since most of my shooting is around 600 yards at matches with the occasional long bomb stage.

Guess I missed that somewhere. 2800 is too early for a BRA. Ive run my BR (28" barrel) at 2850-2875 w about 30.6gr pf Varget with no pressure.

2850 should be money.

 

[Zack_va248]

You need more rds on the barrel to get it fully sped up before it'll settle in. Somewhere around 200-250 or so should see it level off.
I'm running 2900 with 30.8 varget and 2915 29.8 h4895 in Lapua out of a 28" Krieger. I would guess you too will settle in around 2900 or just below.

 

[Billiam1211]

You need more rds on the barrel to get it fully sped up before it'll settle in. Somewhere around 200-250 or so should see it level off.
I'm running 2900 with 30.8 varget and 2915 29.8 h4895 in Lapua out of a 28" Krieger. I would guess you too will settle in around 2900 or just below.

I’m at 200 rounds and I think it’s settled. I’m keeping my H4895 load for now, which is damn near identical to your data, and might reevaluate once it warms up. My SD wasn’t quite as good as yours

 

[Zack_va248]

I’m at 200 rounds and I think it’s settled. I’m keeping my H4895 load for now, which is damn near identical to your data, and might reevaluate once it warms up. My SD wasn’t quite as good as yours

Do you neck mandrel/anneal?

 

[Billiam1211]

Do you neck mandrel/anneal?

Yeah all of the above, it was brand new Alpha brass on its first firing and my SD was 12 so I’m guessing that’ll settle down on the next firing

 

[kthomas]

Satterlee method doesn't mean shit. That ladder means nothing as far as any potential "nodes", but does give an idea of what charge weight gives what velocity (which still doesn't mean much until the barrel has fully sped up), and where pressure may begin.

This is what I would do:

- Load up ~29.5 grains of H4895, and shoot that as your FF loads. (This is my FF load, but its with Lapua brass. No experience with Alpha - but just accordingly. Based on your data it looks like it should work okay though).
- Once the barrel has fully sped up, going 30.0+ grains of H4895 is probably where you will end up. I'm currently shooting ~30.3 grains of H4895 in my 6BRA. I went as hot as 30.8 grains, but the juice really isn't worth the squeeze. Just focus on finding a stable velocity, don't go for absolute speed.

Enjoy the 6BRA. It's not picky at all in my testing.

 

[Krob95]

Interesting. Running a 27" 6BRA almost identical to you, alpha brass, 107's and 15k off. First 15 had smooth bolt lift running up to 31.7gr of varget. The next 70? Hard bolt lift. Very minor ejector swipe. I backed it down to 31.2gr for those 70 and while I'm not sure of speeds I figured it would still be in the low 2900 range with out pressure.

This is the first 85 rounds in this barrel so it'll speed up eventually (mod400). But I'm probably just going to run 30.8 and find a good seating depth and send it. The above was virgin brass to get those pieces caught up to the 1x fired brass I have.

Here were my ending shots at 31, 31.4, and 31.7 in my first 8 rounds out the barrel looking for pressure and preliminary speeds and had no hard bolt lift or real ejector swipe. Odd I had hard bolt lift at 31.2, more testing will need to be done I guess.

 

[Krob95]

Update...

I found that if I run my bolt fast and don't let the cases sit in there after approx 5 shots, I have no hard bolt lifts. If I let them sit after the first 5 rounds, hard bolt lifts. I can't imagine varget being that temp sensitive unless sensitivity goes up with age of the powder? Only running 31gr currently.

Anywho, I didn't chrono the latest loads but holding 7mil at 1k with 1-1.5" of vertical is pretty nice

 

[4O6shootist]

6br vs bra is only like 0.7gr extra capacity so 2% increase, that equates into less than 1% extra velocity at SAME psi loads. The main advantage of the ackley is the 40° shoulder arrests majority of case neck growth. Generally an ackley removes body taper, but on the bra, its just a shoulder angle change. My reloading program shows nodes at 2870-2890 with 105-108 bullets with the appropriate powders. Benchrest guys run the bra 2950 but most them are 30" or longer and shooting in covered clean conditions, not field style. Hell my 6gt holds almost 5gr over alpha bra and I run 109s at 2900 from a 28" barrel.

 

[SWgeezer]

From what I have gathered is this is your fireform load? If so you need to sort of ignore the way the primers look. A dry chamber is needed and they have to headspace on something, like jam the lands or create a false shoulder on the neck.

 

[Feniks Technologies]

From what I have gathered is this is your fireform load? If so you need to sort of ignore the way the primers look. A dry chamber is needed and they have to headspace on something, like jam the lands or create a false shoulder on the neck.

An ackley chamber should be .004 shorter than a non ackley chamber.

No jamming or false shoulder require.

 

[Mudflap621]

An ackley chamber should be .004 shorter than a non ackley chamber.

No jamming or false shoulder require.

It should be but isn't always the case unfortunately. I ran into the same issue with false pressure signs forming 6bra brass. After taking measurements and chambering virgin brass I found out that my chamber was a touch long and wasn't crushing on virgin brass. I ended up taking the ejector out and jamming into the lands until my brass was formed.

 

[Feniks Technologies]

It should be but isn't always the case unfortunately. I ran into the same issue with false pressure signs forming 6bra brass. After taking measurements and chambering virgin brass I found out that my chamber was a touch long and wasn't crushing on virgin brass. I ended up taking the ejector out and jamming into the lands until my brass was formed.

If it’s not, have the smith fix it. At least IMO.

 

[SWgeezer]

.004 is pretty thin, I am preparing to load for 6Br or one of the variants so I have been reading all the 6BR related reloading, it still looks like headspace from fireforming. Easy to check is to reload one of the fireformed cases with the same load.

 

[Mudflap621]

.004 is pretty thin, I am preparing to load for 6Br or one of the variants so I have been reading all the 6BR related reloading, it still looks like headspace from fireforming. Easy to check is to reload one of the fireformed cases with the same load.

The reason for having .004 shorter is to have a crush fit on brass holding it while the shoulder gets blown out.

 

[SWgeezer]

Yes I know why they are shorter.

 

[4O6shootist]

Alpha stated that Stuteville has been chambering go -002 for their ocd bra brass and having very good luck with it.

 

[Billiam1211]

I finally got around to doing a proper load development for my BRA. Listened to everyone's advice and just got to 200 rounds down the tube at a conservative load. Right at 200 rounds my barrel picked up about 40 FPS that's why I decided to redo load development. Looks like my PVA prefit likes both H4895 and Varget. I was running 107 Matchkings, Alpha Brass, 205Ms, 0.020" jump and ran ladders with both Varget and H4895.

The 0.253" group was 30.6 grains of Varget. I'm going to run 29.4 grains of H4895 for now, since I have a bunch of it laying around. 29.4 gr H4895 produced 2,897 fps and SD of 4. No pressure issues at all. Considering it was less than 10 degrees out today, windy as shit, and I was shooting with heavy gloves - I'll take these groups and call it done

 

[SWgeezer]

I finally got around to doing a proper load development for my BRA. Listened to everyone's advice and just got to 200 rounds down the tube at a conservative load. Right at 200 rounds my barrel picked up about 40 FPS that's why I decided to redo load development. Looks like my PVA prefit likes both H4895 and Varget. I was running 107 Matchkings, Alpha Brass, 205Ms, 0.020" jump and ran ladders with both Varget and H4895.

The 0.258" group was 30.6 grains of Varget. I'm going to run 29.4 grains of H4895 for now, since I have a bunch of it laying around. 29.4 gr H4895 produced 2,897 fps and SD of 4. Pressure issues seem to have gone away too. Considering it was less than 10 degrees out today and windy as shit, I'll take these groups and call it done

It will be interesting to see what this load does at 80*

 

[Billiam1211]

It will be interesting to see what this load does at 80*

I've tested H4895 temp change from winter to summer in another rifle and it changed 10 fps in the summer time. I'm in IL so it can be below 0 in the winter and summers are usually around the 90s. I'm assuming that when it gets hot out, I'll have to drop my charge 0.2gr to keep the velocity the same.

I can update in a couple months once it warms up and post the delta in velocity. I doubt I'll hit any pressure though. Just goofing around with loads I went up to 2,950 and still didn't hit any pressure signs, but based on what everyone else was saying I opted to stick around the lower nodes.

 

[Rocketmandb]

An ackley chamber should be .004 shorter than a non ackley chamber.

No jamming or false shoulder require.

One of the best things about a BRA vs some of the other 6mm rounds requiring fire forming.

 

[Rocketmandb]

I doubt I'll hit any pressure though.

I run at 30.6 gr of H4895 with 105s, and I'm close to pressure (30.8 will get me a sticky bolt on hot days). Even though you have a different barrel, 107s, etc., I seriously doubt you'll ever approach pressure at more than a grain less of powder. Heck, your load is what I fire form off of.

 

[4O6shootist]

@Billiam1211 you running alpha or lapua? I know alpha bra is 0.7gr lower than lapua, so equal speed prob take a half grain less in alpha vs lapua.

 

[Billiam1211]

@Billiam1211 you running alpha or lapua? I know alpha bra is 0.7gr lower than lapua, so equal speed prob take a half grain less in alpha vs lapua.

I’m running Alpha brass thats on its second firing