6gt

[96C]

FWIW:

Load dev today with Berger 109 LRHT in the 6GT.
This is the first load up with 109 Bergers, seated at 0.060" off, was just a starting point in the middle somewhere... But it worked.
All groups were under .5 MOA at 100 meters. Best was 0.396 MOA, having not touched seating depth or the truner, promising.

Rifle: AI AT-X
Barrel: Bartlein 25" 1:7" (1704 rounds through it)
Reamer: Alpha .120FB
Powder: ADI AR2208 (Varget)
Primers: GM205M
Brass: Alpha
Seating depth CBTO: 1.880"

Sizing press: Area 419 Zero
Seating press: K&M arbor with standard force dial indicator
FL Sizing die: SAC modular
Seating die: Forster arbor with VLD stem
Scales: Auto Trickler V3

Chronograph: Garmin Xero

 

[diggler1833]

Sidetracked into absurdity again, I furtherd my little test into a hunting load with the 95gr Nosler BT and VV N150 that I have an excess of both. I'm only using these components for the testing.

My goal was 3K FPS and 2/3 MOA accuracy for consecutive five shot groups (27" barrel). I figured that it could be a dandy little coyote round out to 400 or so if I could meet those two parameters.

Unfortunately, I can't really say that the accuracy will be there. I shot today prone with a rear bag, so no chronograph numbers, but I did hit 3K FPS on the nose twice at 33.5gr during a seating depth test. Both times SDs were 4 and 6 respectively.

I think this is about as good as it is going to get. Not horrible for a hunting bullet across the board, but that group of 1.1" at 33.9 is probably the worst this barrel has shot. As such, I don't think that I hit my goal.

FWIW this barrel hammers with N150 and the 105 hybrid, it just hammers a little better with H4350.

It was a fun experiment anyway. I did have a bit of a perceived hang fire in the first group...don't know if that was me, or if it actually happened.

Dots are 3/4".

 

[Gray shooter]

FWIW:

Load dev today with Berger 109 LRHT in the 6GT.
This is the first load up with 109 Bergers, seated at 0.060" off, was just a starting point in the middle somewhere... But it worked.
All groups were under .5 MOA at 100 meters. Best was 0.396 MOA, having not touched seating depth or the truner, promising.

Rifle: AI AT-X
Barrel: Bartlein 25" 1:7" (1704 rounds through it)
Reamer: Alpha .120FB
Powder: ADI AR2208 (Varget)
Primers: GM205M
Brass: Alpha
Seating depth CBTO: 1.880"

Sizing press: Area 419 Zero
Seating press: K&M arbor with standard force dial indicator
FL Sizing die: SAC modular
Seating die: Forster arbor with VLD stem
Scales: Auto Trickler V3

Chronograph: Garmin Xero

View attachment 8580681View attachment 8580682

96C
Good data. Your graph is titled standard and loose neck, i am assuming this is referring to neck tension? What did you find or see in any difference with the group size with the 2 different neck tension? What was your neck tension?

 

[96C]

96C
Good data. Your graph is titled standard and loose neck, i am assuming this is referring to neck tension? What did you find or see in any difference with the group size with the 2 different neck tension? What was your neck tension?

I had to use a kinetic hammer to pull the initial load data lot after finding that some of the brass in that box still had media from the dry tumbler in the flash holes (idiot). Decided to not re-size the cases (still primed) and couldn't be bothered pulling the decapping pin out. The necks were at that point a bit looser, as seen on the arbor press force dial.

Die is a SAC 6 GT + 0.2410" Decapping Expander Mandrel with .263" Neck / Shoulder Bushing.

I was only able to fire one round of the 'loose' rounds at paper, mirage became a major issue at that point in the day so the rest were shot at steel to just get velocity information sorry.

The single group that can be compared:

Charge	Tension	MV AVG	ES	SD	Group
33.6	Standard	2860.2	29.5	9.5	.399 MOA (11.6mm)
33.6	Loose	2866.8	10.8	3.8	.506 MOA (14.7mm)

Overall, the velocity only jumped up marginally on the looser neck cases, but I'd be less inclined to trust them being beaten up the magazine and storage compared to the standard necks. It may never be an issue, but still.... They slipped in with almost zero effort on the arbor press.

 

[davere]

I had to use a kinetic hammer to pull the initial load data lot after finding that some of the brass in that box still had media from the dry tumbler in the flash holes (idiot).

Did you actually have misfires or hangfires? Or did you find in some unloaded cases and decide to be cautious? Just curious.

I eliminated this as a potential issue by moving to really fine grade walnut shell media - but I recall (and can't find a reference now) that Litz did some experiementation around corn cob in the flash hole, and found that it generally didn't make much/any difference (like, everything at least went bang normally in his experiments)

 

[hairy_pineapple588]

36g of H4350, Virgin Alpha brass, CCI 450, and Berger 109’s. This is my first Custom Rifle Barrel and not sure about others but it took longer than any of my Bartlein or Krieger to break in.

 

[hairy_pineapple588]

Anyone shooting a 6GT proof prefit? Good results?

 

[mike278]

Anyone shooting a 6GT proof prefit? Good results?

This is my first time shooting a Proof prefit. I can't complain about the results. I just picked a load that had the velocity I was looking for (2830ish). This is a bunch of 3 shot groups just checking for a good seating depth. These are the lengths with a comparator, so the numbers are funky. I can't swear that the larger groups aren't just my sloppiness. I don't have 200 rounds on the barrel yet, but still getting single digit SDs. Shooting with a KGM can.

 

[mike278]

There are a few older posts here about N150 but is anyone using N150 currently and is it a 1:1ish replacement for Varget?

I just started experimenting with it, and it seems like it takes a little less 150 for the same velocity. I'm running 32.6gr in a 26" Proof with 107SMKs at 2830ish.

 

[davere]

This is my first time shooting a Proof prefit. I can't complain about the results. I just picked a load that had the velocity I was looking for (2830ish). This is a bunch of 3 shot groups just checking for a good seating depth. These are the lengths with a comparator, so the numbers are funky. I can't swear that the larger groups aren't just my sloppiness. I don't have 200 rounds on the barrel yet, but still getting single digit SDs. Shooting with a KGM can.View attachment 8588423

Realize that with a .024 spread across all those seat depths, you're not really moving the needle enough between groups to see any appreciable difference due to seat depth changes. Heck, over 30 rounds, you moved the lands about .002 - almost a full interval (erosion of about .005 per 100 rounds). You might as well consider those all to be one big group (it's not a bad group - maybe one flyer). You really need to have bigger intervals to see real difference in seat depth effects - .020-030 between depths.

 

[mike278]

Realize that with a .024 spread across all those seat depths, you're not really moving the needle enough between groups to see any appreciable difference due to seat depth changes. Heck, over 30 rounds, you moved the lands about .002 - almost a full interval (erosion of about .005 per 100 rounds). You might as well consider those all to be one big group (it's not a bad group - maybe one flyer). You really need to have bigger intervals to see real difference in seat depth effects - .020-030 between depths.

Right, I already had the general ballpark, just doing the fine tuning. I realize it's going to change. I was looking for the long size to load to, allowing for erosion ( essentially the shorter length/ longer jump) where it would open up. Not getting too wrapped around the axle about chasing the lands.

 

[hairy_pineapple588]

Y’all do seating depth test? I haven’t seen seating depth matter at all. Well not with my Berger 109’s or 140’s

 

[hairy_pineapple588]

This is my first time shooting a Proof prefit. I can't complain about the results. I just picked a load that had the velocity I was looking for (2830ish). This is a bunch of 3 shot groups just checking for a good seating depth. These are the lengths with a comparator, so the numbers are funky. I can't swear that the larger groups aren't just my sloppiness. I don't have 200 rounds on the barrel yet, but still getting single digit SDs. Shooting with a KGM can.View attachment 8588423

So overall it’s pretty good. Those are some great 3 shot groups.

 

[mike278]

Y’all do seating depth test? I haven’t seen seating depth matter at all. Well not with my Berger 109’s or 140’s

I'm being a poor. The SMKs are easier to find and cheaper. They don't seem to be very preferential to seating either, though.

 

[4O6shootist]

I'm being a poor. The SMKs are easier to find and cheaper. They don't seem to be very preferential to seating either, though.

Seat 107s at 25-35 off and go shoot stuff. They do well back around 70-80k off too. Found Berger hybrids to be very similar.

 

[diggler1833]

Y’all do seating depth test? I haven’t seen seating depth matter at all. Well not with my Berger 109’s or 140’s

Usually yes, sometimes no.

Since we're in the 6GT thread:

Mine has a definite preference for seating depth with the 105 Hybrid. It isn't a huge swing in accuracy, but it makes a difference of about 1/3-1/2 MOA. Is that repeatable? Yes. Can I shoot the difference prone/rested from my shop? Yes. Would I be able to shoot two 500 round groups and tell a difference? Who knows because I'll eventually throw a shot without realizing it, but consecutive 4x5s show the trend.

I've experienced this as well with the 130 AR OTM in 6.5x47L, and the 215 Hybrid in the 300NM also.

I've found that if asking genuine accuracy advice, it sometimes suits better to go over to https://forum.accurateshooter.com/ and ask the benchrest and F-class guys. Too many howler monkeys here (and I'm frequently one of them).

 

[padom]

Y’all do seating depth test? I haven’t seen seating depth matter at all. Well not with my Berger 109’s or 140’s

Absolutely. Haven't seen it matter depends on what your after.. When I do seating depth tests after finding my OCW, there is always a seating depth that stands out from the rest...

For example, all of these groups are probably more than acceptable for 90% of the people out there, but one clearly stands out from the rest and thats the one seated about 0.020" off lands..

 

[davere]

Y’all do seating depth test? I haven’t seen seating depth matter at all. Well not with my Berger 109’s or 140’s

You might find this useful: https://precisionrifleblog.com/2020/04/28/bullet-jump-research-and-load-development-tips/

At least in terms of philosophy, anyway. If you're shooting PRS, you need to ensure you've got a jump distance that will work over, say, .010-.015 variation, if you're going to make it through a 200+ round weekend at a two day (depending on how much you shoot on the train up day). The data tends to show that short jumps - .010-.030 - can work really well, but they fall apart quickly as the lands erode, so you have to "chase the lands". Same goes for jammed loads. Those techniques work really well - for games that you're shooting smaller round counts, or where you're loading at the range to suit changes in the rifle's condition through the match, etc. Meanwhile, for many bullets, jumping .050-.070 seems to also work - maybe not quite as tight as .020, but it tends to hold together through a lot of erosion from there.

For instance, over the last two years, I shot the 108 Berger BT in 6GT. I started with a .060 jump, and it was still shooting the same after about 1200 rounds. For giggles, I measured the lands - I was now jumping about .120. I adjusted my seating die to jump .060 again, and ran it for another 1300 rounds with no changes.

I've since switched to the 109 LRHT - and it seems to be just fine at .060, as well. One of the bullets used in the PRS Blog study is the 105 Hybrid - it's pretty much same (and the guys I know shooting that bullet have had results that match the data in the blog)

 

[hairy_pineapple588]

I just haven’t seen this be such a measurable change to be relevant. I measure on new barrels and put it .050-.060 and leave it there. I don’t think I’m not placing in the top 10 because of bullet seating but that’s me. I’ve done the tests and read those articles but that’s just what I’ve found. In my experience it’s the Indian and not the arrow. Ive talked to a few very good shooters winning matches and they can’t even tell you their jump. To each their own.

 

[CK1.0]

Y’all do seating depth test? I haven’t seen seating depth matter at all. Well not with my Berger 109’s or 140’s

I'm in the camp that doesn't think seating depth matters much. These days I load as short as I can while still keeping the bullet's bearing surface above the neck/shoulder junction, and voila, always shoots. I don't even know where my lands are and haven't bothered to measure to find out over my last couple of barrels.

That said, given a choice, I'd always rather have a healthy jump than be really close to the lands or jam. I feel like I always get less vertical dispersion and a better waterline downrange past 600 yards with more jump, and I like that my barrel doesn't change much at all as the rounds add up without me having to change anything.

 

[hairy_pineapple588]

I'm in the camp that doesn't think seating depth matters much. These days I load as short as I can while still keeping the bullet's bearing surface above the neck/shoulder junction, and voila, always shoots. I don't even know where my lands are and haven't bothered to measure to find out over my last couple of barrels.

That said, given a choice, I'd always rather have a healthy jump than be really close to the lands or jam. I feel like I always get less vertical dispersion and a better waterline downrange past 600 yards with more jump, and I like that my barrel doesn't change much at all as the rounds add up without me having to change anything.

This is what I do. just keep the bearing surface and neck shoulder junction close ish and run it.

 

[padom]

I just haven’t seen this be such a measurable change to be relevant. I measure on new barrels and put it .050-.060 and leave it there. I don’t think I’m not placing in the top 10 because of bullet seating but that’s me. I’ve done the tests and read those articles but that’s just what I’ve found. In my experience it’s the Indian and not the arrow. Ive talked to a few very good shooters winning matches and they can’t even tell you their jump. To each their own.

For PRS, no it doesnt matter as much....

 

[davere]

I just haven’t seen this be such a measurable change to be relevant.

It seems to be super dependent on a number of factors, including the throat profile, the rifling style, the bullet itself, etc (mostly the bullet design). When everyone was trying to run VLD style shapes, it mattered more - those bullet profiles seem to be really picky about it. For tangent and hybrid style designs, it matters much less, seemingly. Anecdotally, we've seen some combos locally where that doesn't seem to hold true - but even then, you have to change jump by large amounts (.030 intervals) to see the difference.

 

[diggler1833]

I just haven’t seen this be such a measurable change to be relevant. I measure on new barrels and put it .050-.060 and leave it there. I don’t think I’m not placing in the top 10 because of bullet seating but that’s me. I’ve done the tests and read those articles but that’s just what I’ve found. In my experience it’s the Indian and not the arrow. Ive talked to a few very good shooters winning matches and they can’t even tell you their jump. To each their own.

Big difference too between PRS and benchrest. Your discipline of choice will have a lot more to do with shooting skill than reloading intricacy.

 

[CK1.0]

I just haven’t seen this be such a measurable change to be relevant. I measure on new barrels and put it .050-.060 and leave it there. I don’t think I’m not placing in the top 10 because of bullet seating but that’s me. I’ve done the tests and read those articles but that’s just what I’ve found. In my experience it’s the Indian and not the arrow. Ive talked to a few very good shooters winning matches and they can’t even tell you their jump. To each their own.

I think the problem is guys make too many decisions based on what they get at 100 yards. I think sometimes guys are chasing ghosts and that's where the unnecessary hair-splitting begins.

I don't give a shit about groups at 100 yards, and personally think it's a poor metric to use when measuring what our rifles are capable of. I can shoot bugholes one day, and 3/4" of inch another depending on the million and a half variables in play, but in general, if I average ~.3"-.4" and can print 1/2" on demand I move on.

(Most of my shooting at 100 is in the interest of having a really solid zero on my gun.)

 

[hairy_pineapple588]

I think the problem is guys make too many decisions based on what they get at 100 yards. I think sometimes guys are chasing ghosts and that's where the unnecessary hair-splitting begins.

I don't give a shit about groups at 100 yards, and personally think it's a poor metric to use when measuring what our rifles are capable of. I can shoot bugholes one day, and 3/4" of inch another depending on the million and a half variables in play, but in general, if I average ~.3"-.4" and can print 1/2" on demand I move on.

(Most of my shooting at 100 is in the interest of having a really solid zero on my gun.)

I agree with this all. That’s my thoughts also. Get a solid zero and take out to distance. Under half moa, I am happy.

 

[padom]

I think the problem is guys make too many decisions based on what they get at 100 yards. I think sometimes guys are chasing ghosts and that's where the unnecessary hair-splitting begins.

I don't give a shit about groups at 100 yards, and personally think it's a poor metric to use when measuring what our rifles are capable of. I can shoot bugholes one day, and 3/4" of inch another depending on the million and a half variables in play, but in general, if I average ~.3"-.4" and can print 1/2" on demand I move on.

(Most of my shooting at 100 is in the interest of having a really solid zero on my gun.)

A lot of people shoot 100yd for load development because it typically requires less components, not factoring in environmental variables as much. But anyone not doing load confirmation at distance after choosing their final load is just asking for unknowns when it counts, whatever your game of choice is...

I do all my load development and seating depth testing at 100 or 200yd then do load confirmation at 800 or 1000yd. If all goes well, I true my Kestrel at the longest distance then dial up some dope at 400, 600, 800 and makes sure everything is spot on.

For example, the above seating depth test I posted above... I tested that load at 800yd after settling on my seating depth test and it hammered. I then trued my kestrel at that 800yd and here is the very next shot dialing what the kestrel spit out for 400yd after truing.. Doesnt get much more dead on then that..

As long as you have a good system and its repeatable and know what your doing and why, then youll get the results you want.

 

[CK1.0]

A lot of people shoot 100yd for load development because it typically requires less components, not factoring in environmental variables as much. But anyone not doing load confirmation at distance after choosing their final load is just asking for unknowns when it counts, whatever your game of choice is...

I do all my load development and seating depth testing at 100 or 200yd then do load confirmation at 800 or 1000yd. If all goes well, I true my Kestrel at the longest distance then dial up some dope at 400, 600, 800 and makes sure everything is spot on.

For example, the above seating depth test I posted above... I tested that load at 800yd after settling on my seating depth test and it hammered. I then trued my kestrel at that 800yd and here is the very next shot after truing.. Doesnt get much more dead on then that..

As long as you have a good system and its repeatable and know what your doing and why, then youll get the results you want.

I get it.

I guess my point is that sometimes guys go overly bananas with "load development" at 100 yards to the point where they're chasing their tales.

At my club at least, there are routinely a few guys who are on never-ending "load development quests", and I hear shit like "My load was shooting great the other day and today I can't beat a 1/2", so it's back to the drawing board" and then they'll say something about going up or down a couple of tenths of a grain in powder, or playing with their seating depth some more, etc, blah, blah, blah.

With me, if my gun was shooting good and printing my usual (~.3-.4", 1/2" on demand), and then the next range trip it's not... I'm just more the type that will look in the mirror instead of dicking around with my load. I'll maybe just throw on a ball cap (because maybe it's just the different lighting conditions?) or rebuild my position, or IDK, just try harder, and it usually fixes itself.

Like a lot of reloading stuff, I feel like there's a point where it can become a Rorschach test and guys will see what they want to see or keep unnecessarily dicking around with stuff until they think they are seeing what they want to see, when the truth is probably that most of the time the gun is working fine and it's the shooter that needs the adjusting lol.

IMHO, a plate at 500-600 yards on a calm day is way more useful for finding out if my load/gun is working good than 100 yards, as that close-in, it can be hard to determine anything concrete as to why a group is a .3" or a .5".

(I'm with you though lol) 1250 yards:

 

[davere]

For example, the above seating depth test I posted above... I tested that load at 800yd after settling on my seating depth test and it hammered. I then trued my kestrel at that 800yd and here is the very next shot after truing.. Doesnt get much more dead on then that..

Doesn't that say 400?

 

[padom]

Doesn't that say 400?

It does, Im not sure what your getting at? Very next shot at 400yd after truing at 800yd... ??? I never said that was at 800yd... I said I confirmed my load at 800yd and trued my kestrel at 800yd then this was the very next shot after truing.. Confirming my load and my trued kestrel was dead on....

 

[Dead Eye Dick]

I think the problem is guys make too many decisions based on what they get at 100 yards. I think sometimes guys are chasing ghosts and that's where the unnecessary hair-splitting begins.

I don't give a shit about groups at 100 yards, and personally think it's a poor metric to use when measuring what our rifles are capable of. I can shoot bugholes one day, and 3/4" of inch another depending on the million and a half variables in play, but in general, if I average ~.3"-.4" and can print 1/2" on demand I move on.

(Most of my shooting at 100 is in the interest of having a really solid zero on my gun.)

WHAT HE SAID ^^^^^^

Call me crazy, I get a 100 yard zero on a new barrel and do my best to never worry with 100 yards again for centerfire. I check hits on steel out to furthest distance the range offers, and then true the Kestrel and let it go.

Why would anyone, even when DT has just been elected president would anyone, ANYONE want to waste precious bullets, powder and primers on silly holes in paper.

When I do check grouping, I do at 300 yards. Rather have a one inch group at 300 yards (with the rounds hitting where I was aiming) than a thousand tiny groups spread all over the paper at 100 yards.

 

[davere]

It does, Im not sure what your getting at? Very next shot at 400yd after truing at 800yd... ??? I never said that was at 800yd... I said I confirmed my load at 800yd and trued my kestrel at 800yd then this was the very next shot after truing.. Confirming my load and my trued kestrel was dead on....

Because the way you wrote it - "I then trued my kestrel at that 800yd and here is the very next shot after truing.." implies that next shot was at 800... And I was just giving you some (intended to be good natured) crap about it....

 

[4O6shootist]

Seating depth matters, these are 10 shot groups from a 22cm with 88eldm, rifle def prefers that 40-50k jump range. Round count was around 60 when I started on the new barrel. Now it's over 350 rounds, still shows major preference to 40-50k jump over anything closer to lands.

Reason for cut and placed targets, as I shot the last 3 groups next day, and I had the target put upside down. So I interpolated them over same poa is previous seating depths.

 

[CK1.0]

It seems to be super dependent on a number of factors, including the throat profile, the rifling style, the bullet itself, etc (mostly the bullet design). When everyone was trying to run VLD style shapes, it mattered more - those bullet profiles seem to be really picky about it. For tangent and hybrid style designs, it matters much less, seemingly. Anecdotally, we've seen some combos locally where that doesn't seem to hold true - but even then, you have to change jump by large amounts (.030 intervals) to see the difference.

Shooting VLDs is really the only time I’ve ever really messed with seating depth and felt like I saw a real change.

For example, lots of guys seem to hate 108ELDMs because they’re long as hell and are VLDs, but I’ve shot thousands of them and think they’re just fine, just IME they kind of suck at the usual 0.020” off everyone always defaults to. From jam to ~0.010” off they seem to work ok, and IME they work even better at 0.060”-0.100” off jumping a bunch.

But interestingly, depending on one’s freebore, even with those, if I were to try them again I’d still probably do what I’ve been doing lately and load them as short as I can while keeping the bullet’s bearing surface above the neck/shoulder junction… as that'd put them close to jam in my SAAMI 6GT (IIRC .123” freebore) and would have them jumping a healthy amount in my SAAMI 6CM (IIRC .183” freebore).

 

[Black Greyhound]

26" Bartlein barrel, 1:7.5 twist
Berger 109 LRHT
Alpha Brass
Federal 205M
Varget 33.8gr, 2922.9 fps, SD 2.4, ES 6.1 @ 90*F, 2906.6 FPS @ 35*F (super temp stable)
0.20 off lands
0.2-0.4 MOA
This may be a little spicier than a lot of people are running for PRS these days, but this is by far the most consistent speed and precision in my specific rifle.

 

[sierra2]

Look what showed up on Midway’s page! Yay…more options. Now, where’s that Lapua brass we’ve been waiting for?

 

[Gogga]

No Lapua 6GT brass here (UK) yet. I'm expecting it sometime in Q1...

 

[TheOE800]

No Lapua 6GT brass here (UK) yet. I'm expecting it sometime in Q1...

The .300WSM announced at the same has been shipping for a couple months too…what are those Finns up to?

 

[ballisticdaddy]

Waiting on Lapua brass and then paying a premium for it when Aplha is just as good, cheaper and currently AVAILABLE!

 

[TheOE800]

Aplha … currently AVAILABLE!

Not since fall last year

 

[CK1.0]

Not since fall last year

Yep, I had pre-ordered a bunch of Lapua and then missed the boat on the Alpha stuff when it was available again… never again lol.

 

[Gogga]

Waiting on Lapua brass and then paying a premium for it when Aplha is just as good, cheaper and currently AVAILABLE!

Unfortunately Alpha is harder to get here and a lot more expensive.

 

[TheOE800]

Yep, I had pre-ordered a bunch of Lapua and then missed the boat on the Alpha stuff when it was available again… never again lol.

I probably should have preordered some Lapua

 

[ballisticdaddy]

Unfortunately Alpha is harder to get here and a lot more expensive.

Can't be harder to get than Lapua as it is still not available, you could do 6.5x47 Lapua and then resize to GT as that is the parent case

 

[Gogga]

Can't be harder to get than Lapua as it is still not available, you could do 6.5x47 Lapua and then resize to GT as that is the parent case

Lapua as a brand is much easier to obtain. There hasn't been any 6.5x47 available for quite some time and it is a lot of work to make 6GT from it. Far easier to wait for the launch

 

[Kadams1563]

With it being only 5 shot strings you can see if one round was way off from the others.

Either way I wouldn’t worry about it. If your velocity is that close you would have a great numbers.

With it being new brass there is no telling where that one piece was in the scope of things. I wouldn’t worry just continue to shoot your “break in” then do another load development after 200 rounds or so on the barrel.

Edit I can’t read lol. See you already have 400 rounds then I would just keep on loading and increase by little bits to gain a bit more velocity and see if the numbers get better.

Another edit. You typed there was a spread of 60FPS but your photos show they are almost identical.

 

[hairy_pineapple588]

Virgin Alpha
36.3g h4350
Berger 109’s
cci450
26” Crb

 

[BravoSector1]

Anyone shooting a 6GT proof prefit? Good results?

I'm shooting a 26" proof prefit in my AI AT. Running Hornady 105s to bang steel. Touching lands, 34.2 gn of Varget with an average of 2,983. I think I'm seeing a little pressure sign (very slight ejector swipe) so I'm going to back off to 34gn even and see what that produces. Still under 100 rounds down the new tube and produced a .37" 5 shot group last outing. Looking forward to a full summer of shooting and see what this thing will do.

 

[CK1.0]

I'm shooting a 26" proof prefit in my AI AT. Running Hornady 105s to bang steel. Touching lands, 34.2 gn of Varget with an average of 2,983. I think I'm seeing a little pressure sign (very slight ejector swipe) so I'm going to back off to 34gn even and see what that produces. Still under 100 rounds down the new tube and produced a .37" 5 shot group last outing. Looking forward to a full summer of shooting and see what this thing will do.

I doubt you'd lose any accuracy backing it down even more if you wanted to.

IMO/IME anywhere in the ~2800-2900fps range is kind of magical with the 6GT, without ever having to step on the brass, smoke the barrel too fast, or think about pressure issues.

I've been shooting only 33gn of Shooter's World Precision Rifle for 2000+ rounds now with 106s getting 2800fps, and it's a pussycat recoil-wise and still hammers out far and prints small groups in close with SDs in the 4-6 range over 20 shots. The only reason I'd dial up to 2850-2900fps is for more smack on plates with the 106 (and I might at some point), but it's been shooting so well "slow" that I just haven't fucked with it, and running it slower has probably made me better at picking up impact locations on closer steel inside 400-500 yards.

 

[davere]

I switched up to the 109 this year rather than increasing speed for that same reason - carry just a little more ass to longer range targets….