6gt
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30gn in a BR case is a lot more case-fill than 33gn in a GT, I’m at maybe ~80% full or so… higher fill = more pressure = more speed I’d guess…
Alpha is just as good. 2800+ with a 112 in a 26" br is pushing it pretty hard.But you don’t have Lapua brass
Brass is looking good so far after 4 firings, I’ll find out….
Are you going to load to match the overall length of the Hornady Match factory ammunition?
Lapua brass and a good sizing die will allow a guy to run warm for a long time. Same thing with alpha, it's very tough in web/case head.
I anneal after every firing.
Out of the original 300 pieces of Alpha brass I started with I’m down to about 220 pieces. Lost some at matches, trashed a few and probably have thrown away 40 for loose primer pockets.
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My first GT barrel just didn’t like to be pushed hard. Ended shooting 109 Hybrids at 2778fps with Varget but it was stupid accurate and like yours nice smooth recoil.
yes to start been shooting Berger 109 hybrids but they do not exist anymore
It's been a bit since I have been able to shoot due to injuries that required surgery. But I am back on my feet, not 100% but can shoot. Today I tested N555 with 110Atips in my 6GT. TL3, 27" straight taper Xcaliber 7.5 twist 5R barrel in MDT ACC Elite chassis with ZCO scope. Brass is Alpha OCD on 11th firing. Everything was shot with bipod and rear bag. No pressure issues.
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2850 and 2920 in a gt hammering.......they all do that! Good shooting.
That will work. 37.6 of N555 under 110 Atip at .040 off lands. 800 yard yote. That was with virgin Alpha OCD brass to. Just ran mandrel and 3 way cutter to clean up case mouth, not really trimming them. Should tighten up after first firing.
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Good evening lads,
With 110gr ATIP's, what did you find personally to be the optimal jump in your barrel?
I've just begun load development on a brand new 26" 1:7" bartlein with Alpha OCD brass and AR2208 powder.
MV will settle around 2800 most likely with approx 34.2gr
I picked a random jump of 0.060", 10 groups were hovering around 0.5 MOA at 100m so not a bad start.
Keen to hear your thoughts.
With 110gr ATIP's, what did you find personally to be the optimal jump in your barrel?
I've just begun load development on a brand new 26" 1:7" bartlein with Alpha OCD brass and AR2208 powder.
MV will settle around 2800 most likely with approx 34.2gr
I picked a random jump of 0.060", 10 groups were hovering around 0.5 MOA at 100m so not a bad start.
Keen to hear your thoughts.
Not the 110s, but with the 106 A-Tips I was jumping ~35 thou, and they shot great (wish I had bought more while they were out there).
I did zero load development and was just trying them out, so I loaded them the same as I do with 112MBs I've been running for a while, same charge, didn't touch the dies. Due to their more tangent-ish ogive, they ended up ~35 thou off (with the same seating die, the more VLDish MBs end up 50 thou off).
Alpha Gay Tiger brass + 33gn SWPR yielded 2825fps out of a Proof SS 26" prefit.
I didn't shoot any 100 yard groups, but here's 6 shots at 750 yards off a cattle gate/Shmedium bag, 33% IPSC:
I did zero load development and was just trying them out, so I loaded them the same as I do with 112MBs I've been running for a while, same charge, didn't touch the dies. Due to their more tangent-ish ogive, they ended up ~35 thou off (with the same seating die, the more VLDish MBs end up 50 thou off).
Alpha Gay Tiger brass + 33gn SWPR yielded 2825fps out of a Proof SS 26" prefit.
I didn't shoot any 100 yard groups, but here's 6 shots at 750 yards off a cattle gate/Shmedium bag, 33% IPSC:
I'm jumping the 112MBs 50 thou to the lands and would have tried more if I had more freebore like you (the boattail is below the neck/shoulder junction in my brass, which traditionally some say is bad, but increasingly I don't think really matters).
I've also had great luck with them jumping all the way out to 100 off in 6CM.
IME they like to jump (and IIRC Proof uses a standard SAAMI chamber, .119”FB for the GT, .183”FB for the CM).
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I dis not do a seating test. I picked .040 as my start and had great results so all I did was charge weights. I did another charge weight test in .2 grains and ran it twice, new barrel and just had 100 rounds on it when I started with charge weight testing, barrel was still settling. The 37.6 load was starting to really shine and it is on a barrel time in QL. So I just went with it. 51 shots recorded with an SD of 4.3 on virgin brass. Sub half inch groups and it performs at distance. I am shooting a match this weekend so we will see how it does. I have seen others seat from .010 to .050 with good results. It does not appear that Atips are very sensitive to jump. You said your barrel is new. I would get at least 100 to 150 on it before I would do any real testing. I have noticed this last year that most of my guns like a seating depth that puts the bearing surface right in front of the neck shoulder junction. That is how I landed at the .040 number.
Man I found them to be kinda picky to get bughole accuracy in my 6bra. Found the velocity band of 2820-2830 to produce very little vertical at distance. So then tried from 10k to 80k off in 007 jump steps. I never could find something that would consistently print group in 2s and 3s. Half moa was bout the best they'd average. I'd love to get them shooting small, as the BC is killer, but I've had issues with them.
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Interesting. What twist are you running and what altitude are you at. I wonder what your SF # is
7.5tw, alt is 3300, DA generally 2000-5000 depending it's it's 0 in January or 85 in July.
I came up with a 1.6 with 1.5 being minimal. You might be seeing some stability issues. I like to see at least a 1.7 to 2.0 as we have seen lower SF numbers do not hold down range. Might shoot good at 100 but print a 6" vertical at 1k. Another way you can tell is to put up a plain white piece of paper and shoot it in different spots. Not shooting a group, just shooting holes all over. Then look at the black ring left on the paper. Look for cemetery in the black. If it is darker on one side then that is a sign the bullet is not 100% stabilizing. The other thing if you have not tried it is run them closer. .010 to .060 I have had good luck with most bullets shooting at .025 to .040 off the lands and they all seem to have the bearing surface just in front of the neck shoulder junction.
Stability Factor is one of those things that is misunderstood as it's not necessarily the hard rule it sounds like... it's not a black-or-white, stable vs unstable thing. Its usefulness depends on, and is subjective, depending on what distance one is shooting.
I've shot a lot of bullets that fall into the "marginally stable" range using Berger's twist rate stability calculator that positively hammer downrange.
Different bullets will stabilize at different distances, and some bullets stabilize faster than others, so just because a bullet may not fully stabilize by 100 yards doesn't mean it can't still hammer downrange (you just may or may not be able to squeak out the smallest groups inside the range when it does fully stabilize, which could be 120, 130, 200, etc). @John Glidewell describes it happening to him the other way, good groups but wonky vertical downrange, and while I've heard other guys talk about experiencing that, for me, having never really shot anything lighter than a 108 in 6mm, it's almost always been the opposite.
Longer VLDish and/or heavyish-for-caliber bullets like 115 DTACs, 110 A-Tips, and 112MBs are almost always going to come up slightly "marginally stable" with Berger's calculator, yet they are efficient and still shoot great, yielding .300+ G7s without having to push the speed limits.
If it makes one feel better, just don't use Berger's calculator, use this one where anything between 1.3 - 2.0 is considered good to go lol: https://www.jbmballistics.com/cgi-bin/jbmstab-5.1.cgi
I've shot a lot of bullets that fall into the "marginally stable" range using Berger's twist rate stability calculator that positively hammer downrange.
Different bullets will stabilize at different distances, and some bullets stabilize faster than others, so just because a bullet may not fully stabilize by 100 yards doesn't mean it can't still hammer downrange (you just may or may not be able to squeak out the smallest groups inside the range when it does fully stabilize, which could be 120, 130, 200, etc). @John Glidewell describes it happening to him the other way, good groups but wonky vertical downrange, and while I've heard other guys talk about experiencing that, for me, having never really shot anything lighter than a 108 in 6mm, it's almost always been the opposite.
Longer VLDish and/or heavyish-for-caliber bullets like 115 DTACs, 110 A-Tips, and 112MBs are almost always going to come up slightly "marginally stable" with Berger's calculator, yet they are efficient and still shoot great, yielding .300+ G7s without having to push the speed limits.
If it makes one feel better, just don't use Berger's calculator, use this one where anything between 1.3 - 2.0 is considered good to go lol: https://www.jbmballistics.com/cgi-bin/jbmstab-5.1.cgi
My newest 6gt........Bartlein 7.5tw carbon rem varm. There's a major issue with it. Walks right about half to 0.6 mil as it warms up, then starts stacking shots. I've repeated this test two more additional times by alternating the first 10 rounds with each ammo sample, and same shit, half mil + walk right, but by round 10 or 12, it'll stack em, highest shot string I've went is 20 and it still under half moa.
I heard a few other have had to same problem with some 6mm Bartlein carbons, talked to one guy directly who had a bad barrel, Bart blames poor heat treat. Usually Bartleins are up to the task, but obviously some junk gets past the door too.
This photo is 3 different loads from a 22" 6gt on a bat action, 107smk at 2880, 108bt at 2860, and 115dtac at 2860. It does this every time I shoot it. Bartlein tells me they won't do anything till I have over 200 rounds and it's settled, blew my mind.
Load development was making me furious, I rarely ever shoot a carbon more than 6-8 rounds, before cooling. This is my 8th gt barrel, I know what they like........and this liked nothing.....until it got too hot to touch. I randomly out of anger one day just kept shooting, and by miracle it shot some tiny groups, blazing hot. It's repeated this tendency 6 times now with 19-20 shot groups.
I heard a few other have had to same problem with some 6mm Bartlein carbons, talked to one guy directly who had a bad barrel, Bart blames poor heat treat. Usually Bartleins are up to the task, but obviously some junk gets past the door too.
This photo is 3 different loads from a 22" 6gt on a bat action, 107smk at 2880, 108bt at 2860, and 115dtac at 2860. It does this every time I shoot it. Bartlein tells me they won't do anything till I have over 200 rounds and it's settled, blew my mind.
Load development was making me furious, I rarely ever shoot a carbon more than 6-8 rounds, before cooling. This is my 8th gt barrel, I know what they like........and this liked nothing.....until it got too hot to touch. I randomly out of anger one day just kept shooting, and by miracle it shot some tiny groups, blazing hot. It's repeated this tendency 6 times now with 19-20 shot groups.
Per our discussions earlier on guys who can spin up AI barrels, the dude I have all my work done by has had the exact same experience with a Bartlein carbon. However he never mentioned having to put 200 through it before they corrected the issue.
Hopefully you get it corrected sooner. Few things less enjoyable than having to burn rounds to get a barrel to settle down.
After may years of running bullets in the 1.1-1.3 range in my 223 and 7mm factory barrels I can see why Brian Litz advises a 1.5 or higher. I struggled with a ever changing ballistic curve when running ballistic programs vs what I was seeing for actual drop at distance when my stability numbers were below a 1.5, I found they were highly dependent on atmospheric conditions. 1.5 or higher have not been a problem with getting predicted drop and actual drops to match up. So while the bullets may still group well with low numbers the BC will changing with temperatures and air pressures.
My proofs have held pretty good groupings through 10 rounds, get em HOT and they'll drift. I've never had a barrel that walked cold, and settled in once hot.
I hear you, and know that scenario exists, where some guys have experienced their dope going to shit under varying conditions while their 100 yard groups still look good.
But, in certain cases, IME, a stability factor that dips into the 1.4s isn't necessarily the end of the world. Chad Heckler and Francais Colon talked about it a couple of times in their Miles to Matches podcast a while back...
It seems to be mostly about yaw. Some bullets come out of the barrel as stable as they'll ever be, and then start to yaw later down the road (the classic good groups, but shit vertical downrange), while other bullets can yaw earlier in their flight and take a bit to settle down, and when they do they sail along just fine... this is my experience with a lot of the 110-115gn 6mm bullets that hammer a distance but stubbornly always seem to hover around 1/2" at 100 unless I'm luckier than usual.
Then there are the bullets that yaw right out of the barrel and never settle down... I think that's the real boogeyman that probably shows up once you get into a SF in the 1.3s (luckily I've never tried/experienced this)...
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Having an issue with flow around the primer with hornady brass. Row of brass on left. Not sure what causes it or what to do to prevent this. Any insight would be helpful. Current load is 32.6 of N150 and cci450 runs 2890fps.
Your load seems pretty safe/typical, but I've never experienced flow around the primer... what is the issue you're experiencing (besides funny-looking brass lol)?
Are you getting gas/smoke in the face, accuracy problems, or does the recoil feel differently or something?
velocity E/S has opened up. seeing a 30 fps variation. not sure if that is related to this but possible.
What do you mean by primer flow. The primers look normal to me. It does look like your pockets may be loose and you are leaking gas between the primer and primer pocket. How many firings on the brass?
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There is some black residue around the primer pocket after firing. approx 25% of my brass has this. the rest does not. pictured brass is after 2nd firing.
Have you done anything to the primer pockets? Ran a hotter load before this?
no prep/uniforming. only tumble in walnut media. same load. all the brass in the last lot of 500 has had this issue for a while. i dont remember seeing this in the last lot.
Pop some of the primers out that did this and look carefully around the perimeter under magnification.
I remember Winchester SRP having an issue with pin holes & results were sim to what you have. Never heard of it with cci 450 though.
Hmm... I'd look for a simple explanation first, and work back from there, it might be your barrel and not your load (especially if your velocity is getting wonky).
Any chance you're seating them long enough where they're jammed or too close to the lands (maybe causing an intermittent pressure spike), or have you checked for a carbon ring that might need some attention? Does a borescope show anything strange going on in there?
will have to find a bore scope, but i do clean after every outing with bore tech carbon remover. my jump started at .067 from the first round and have not checked it since. i am goint to inspect those 20 pieces and report back. i use the same primers in lapua 6.5cm brass and they seat more firmly.
I've got some my original batch of 500 ocd cases from 21 that are on their 4th barrel. 12-14 firings? Ran around 2850-2920 depends on bullet, with H4350 and 450s. Still good on pockets, don't feel like virgin, but still snug. I'd measure your firing pin diameter, VS the diameter of hole in the bolt. Low psi loads won't show flow, but medium and high will if the clearance is too sloppy in the clearance of this twos fit. I get primer flow/dimpling on zermatt actions on medium to higher psi laods but still have round edges on the primer.
Hornady brass(used this before Alpha ocd) has soft pockets and will only last 4-5 reloads at 2900+ with 109-115gr in 26" barrels. Cleaning pockets with certain tooling like the RCBS stiff steel pocket brushes can enlarge and loosen them even faster.
If you started jumping 67 thou, it's not that.
Yes, Hornady brass is shittier than Alpha, and it might be as simple as some of those cases starting to quit after only 2 firings...
...but IDK, I cleaned my barrels for a long time using only Boretech Eliminator... up until I got a borescope and was surprised to learn it wasn't really doing shit besides turning some patches blue while I conducted my very poor (unbeknownst to me) cleaning ritual/routine.
If you haven't looked, I'd assume there's a ring or at least the start of one until you know...
I suppose looking at the firing pin thing is worth a try as well, I'd just rule out the barrel first.
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357Max, how did you decide on the .267 bushing, and what brass are you using?I’m using the SAC die with .267 bushing for 6GT & .247 for 22GT.
Modular Sizing Die – GT
GT dies with .20 Caliber Bushings will not come with a decapping pin. If using an existing GT die, please reach out to us so we can send you a plug for your die to function properly [email protected]shortactioncustoms.com
I started with a whidden FL non bushing die that sized the neck down to .263 (expander ball removed). Made great ammo, but I just wanted to work the necks a little less.
Hornady brass so far & loaded necks measure .272
.267 + a little spring back = .2675 - .268. I use a 21st Century expander die + .2415 or .242 mandrel to finish.
Right or wrong my logic is that I want the expander mandrel to open it up .0015 - .002 to set final neck dimension. No less than .001 as I want the inside of the neck truly round. Working well for me.
I have some new Alpha ocd brass, but haven't loaded any yet.
@357Max, I have Alpha brass, new. The only rounds I have shot in this rifle are the Hornady Match factory ammo (which I stopped using after pierced primers broke my trigger) and a friend's handloads with better primers than Hornady is using.
So I do not have any Alpha brass loaded rounds to measure the neck.
357Max, do you have any suggestions for how I should go about selecting the correct bushing size from SAC?
Initially, as I was researching, I liked the idea of an expander die and mandrel, but I read so many opinions against it here on this site. I don't really know what to do, and, since I am just starting out, I wanted to keep it simple. So I figured I would not use an expander mandrel for now and maybe experiment with it later to see if it makes my groups better.
I have new brass (Alpha). I was going to just primer, chamfer the case with a VLD type chamfer tool in a drill, dump powder in the case, and seat the bullet to start out. So I guess I do not need to resize new brass, right? But when it comes to the second loading, I wanted to use the same SAC sizing die you are using. I had not ordered yet because when I went to order I saw it comes with only one bushing, and I had no idea what size to select.
Any advice you could provide, dumbed down for me, would be very appreciated.
I will be loading either Berger 109LRHT or Sierra 107 SMK (I have both, so probably the Sierras to start out). Varget. CCI 450. If you need to know anything else to answer my question, just ask. Thanks for taking the time to review my overly long post.
So I do not have any Alpha brass loaded rounds to measure the neck.
357Max, do you have any suggestions for how I should go about selecting the correct bushing size from SAC?
Initially, as I was researching, I liked the idea of an expander die and mandrel, but I read so many opinions against it here on this site. I don't really know what to do, and, since I am just starting out, I wanted to keep it simple. So I figured I would not use an expander mandrel for now and maybe experiment with it later to see if it makes my groups better.
I have new brass (Alpha). I was going to just primer, chamfer the case with a VLD type chamfer tool in a drill, dump powder in the case, and seat the bullet to start out. So I guess I do not need to resize new brass, right? But when it comes to the second loading, I wanted to use the same SAC sizing die you are using. I had not ordered yet because when I went to order I saw it comes with only one bushing, and I had no idea what size to select.
Any advice you could provide, dumbed down for me, would be very appreciated.
I will be loading either Berger 109LRHT or Sierra 107 SMK (I have both, so probably the Sierras to start out). Varget. CCI 450. If you need to know anything else to answer my question, just ask. Thanks for taking the time to review my overly long post.
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