Has anyone experimented with berger 109s and h4350. Ive found a good powder node around 36.6 grains resluting in 2900-2930 but im curious as to what everyone is jumping the 109s.
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6gt
- Thread starter Dthomas3523
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I jumped mine .060" around your node at 36.0 h4350 giving me 2850
I think .050 to .070 is a great place to start them for jump. And there always seems to be a great node around 2920fps.
are these all with the .120 free bore it seems as though that will have my bullet pushed way down in the case.
whats yall CBTO if you dont mind me asking. I know everyones going to be a couple thou different but given the fact these are all custom chambers it should be close.
That’s left over match loads from GAP Grind. Was shooting 1 hole at 100. 36.68 of 4350. 2948fps from AB lab. Did have heavy bolt on Saturday during rain storm but not Sunday when sunny. 109s.
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Got my new 6mm GT out yesterday and got some velocities that were a bit higher than I was expecting:
23" barrel, 112gr MatchBurners, 0.070 off jammed, StaBall, Hornady cases,CCI 450s, 80 deg.
38.2 - 2,847 fps
38.5 - 2,845 fps
38.8 - 2,841 fps
39.1 - 2,879 fps
39.4 - 2,947 fps
39.7 - 2,948 fps
40.0 - 2,992 fps
40.3 - 3,011 fps
I was kind of surprised by the big velocity jump between 38.8 and 39.4, and it was accompanied by a pretty significant POI shift. Started seeing some pressure on the cases around 40gr.
23" barrel, 112gr MatchBurners, 0.070 off jammed, StaBall, Hornady cases,CCI 450s, 80 deg.
38.2 - 2,847 fps
38.5 - 2,845 fps
38.8 - 2,841 fps
39.1 - 2,879 fps
39.4 - 2,947 fps
39.7 - 2,948 fps
40.0 - 2,992 fps
40.3 - 3,011 fps
I was kind of surprised by the big velocity jump between 38.8 and 39.4, and it was accompanied by a pretty significant POI shift. Started seeing some pressure on the cases around 40gr.
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You're running the exact same load as me. 36.6gr H4350 in cold weather is 2900, warm weather 2920. I run the 109s at 40k off and it shoots very well in my 28" bartlein 7.5t, been runnig this load for about 1200 rounds now.
Whoops, that's kind of an important omission. It was 6.5 StaBall, updated my post
Wow, I hit pressure way before those weights but have higher speeds I’m at 3025fps at like 38 something. Anything over 3020 I hit swipes. Using alpha OCD. Maybe that’s why.
Yes I'd guess the case capacity of the Alpha must be significantly less to induce such a difference. My velocities are pretty close to what I'd expect given Hodgdon's data. Maybe a hair slower, but given these were the first rounds on this barrel, and it's 23", I'm guessing it will settle in very close to the data.
What is the H2O case capacity of your fired Alpha brass? I measured 3 of my cases from this first trip and got: 45.7gr, 45.6gr and 45.7gr.
When I get some time I'm planning on playing around in QL a little too try and get a starting point for AR-Comp loads. It's certainly fast for this application, but folks seem to be having good luck with Varget, and I'm not going for max velocity, so I may be able to find something decent.
Thank you, and that would be in what is called " a standard freebore chamber" ?
also, where is the gas ring, or the base of the full Dia. of the bullet in relationship to the case's neck body junction.
Again, thank you
also, where is the gas ring, or the base of the full Dia. of the bullet in relationship to the case's neck body junction.
Again, thank you
Standard cut by straight jacket. Th boat tail is in the shoulder.
bearing surface is right at neck shoulder junction
Thank you ,Going,
to have to re think the GT project, as I'd bet everyone has the same design , OR won't tell you what the FB is on their reamer till you buy a $$$$ barrel
to have to re think the GT project, as I'd bet everyone has the same design , OR won't tell you what the FB is on their reamer till you buy a $$$$ barrel
Went back and read a lot of previous posts, seams all bullets used shot well with some amount of jump vs being jamed to just kissing the lands. Also seams most are using long bbl's, {longer that 24" ??
Most are using 6gt for competition or at least a similar practical type shooting.
Jamming and such increases the chance of sticking a bullet at an inopportune time. So most won’t even test it. I’m sure you’ll find some jams that shoot well.
Most will also be using around a 26” barrel. But I’ve seen plenty of shorter 6gt.
Thank you,I was inquiring from strictly an accuracy stand point. All the " fun" I had in my past finally has caught up with me , so now I'm limited to shooting from a bench on 600 and 1100 yd ranges either paper punching or banging steel.
I've been having some strange bullet seating behavior along with inconsistent or very light bullet grip with 112gr Match Burners and GAP branded Hornady cases. I'm using RCBS Matchmaster dies with .266" collet which gives me ~.002" measured neck tension. I'm curious if anyone else has seen these problems, or even if they are really the issue.
I called Josh at PVA to ask about the freebore length on my barrel, and he mentioned that Barnes and to a lesser extent Hornady had had some issues with some bullets having an enlarged what he called a "pressure ring" where the boat tail meets the shank. Josh said bullets with this problem would feel normal during most of the seating process until, at some point resistance sharply dropped off and it felt like the bullet might just drop right into the case.... which perfectly describes the weird feel I've been getting with these loads. In fact, on deeper seating depths, I've been able to push bullets into the case by hand without to much effort even though the ogive should still be well above the case mouth.
I went out and measured some of the 112gr MBs and, admittedly with calipers, the junction of the boat tail and shank does seem to be up to 0.001" larger than the shank itself. I also measured 108gr ELDs, and they have a ring as well, but it seems to be a much smaller difference.
Josh said a large diameter difference was a manufacturing error, I wonder if a smaller .265" collet would help though. Intuitively, it makes sense that a significantly larger ring/bulge being pushed through the case first could act like an expander ball and lead to poor tension on the rest of the bullet once the ring passed the sized portion of the neck.
Anyone else had this problem before? Recommendations, or maybe just go down a collet size and see what happens?
I called Josh at PVA to ask about the freebore length on my barrel, and he mentioned that Barnes and to a lesser extent Hornady had had some issues with some bullets having an enlarged what he called a "pressure ring" where the boat tail meets the shank. Josh said bullets with this problem would feel normal during most of the seating process until, at some point resistance sharply dropped off and it felt like the bullet might just drop right into the case.... which perfectly describes the weird feel I've been getting with these loads. In fact, on deeper seating depths, I've been able to push bullets into the case by hand without to much effort even though the ogive should still be well above the case mouth.
I went out and measured some of the 112gr MBs and, admittedly with calipers, the junction of the boat tail and shank does seem to be up to 0.001" larger than the shank itself. I also measured 108gr ELDs, and they have a ring as well, but it seems to be a much smaller difference.
Josh said a large diameter difference was a manufacturing error, I wonder if a smaller .265" collet would help though. Intuitively, it makes sense that a significantly larger ring/bulge being pushed through the case first could act like an expander ball and lead to poor tension on the rest of the bullet once the ring passed the sized portion of the neck.
Anyone else had this problem before? Recommendations, or maybe just go down a collet size and see what happens?
I would think such a manufacturing inconsistency would show up downrange
since its probably not modeled that way in the design drawings.
i would think so as well but personally id test them just to see...with the pressure ring being a bit larger id guess youll see a bit more velocity and your ESs-SDs open up a bit but id be curious to know for sure how much this will effect your rifles preformance.
That's a bit harder to answer, the rifle is brand new, and the only bullets I've run though it thus far are the 112gr, since I've been able to get ahold of several hundred.
I started with this OCW with StaBall at 200yds, which appeared to give some useful POI shift information. Each of those red dots is the center of a 3 shots, and there were one of two weird flyers that I disregarded because I figured they might have caused by the new rifle or even my shooting at the time.
From that I decided to try 30, 60 and 90 thou off the lands for 38.6gr and 39.5gr @ 300 yds.
There's some unexplained flyers in there too, along with some just plain bad groups.
So I'd say yes, something is affecting performance (I was shooting my Sig Cross at half the weight better than this on the same trip), but hard to tell if the problem is the bullets or something else on the new rifle. BTW, I've checked all the action and scope mount screws a few times.
I've been reloading for a while, and the bullet seating seemed off compared to pretty much all the other cartridges I've loaded, so that's where I started looking. I guess next step would probably be to see if I can get it to shoot with the box of 108gr ELDs I have.... maybe throw in a .265" collet while I'm at it.
Here's a pic of the rifle itself.
that is a nice rifle!
thats said my suggestion would be to stop shooting load development and or shooting groups to verify a load at 200 and 300yds because the smallest movement on your part becomes a huge disappointment on target...i know because ive been here myself.
i would take your 38.5g load and run a seating test starting at .010 off the lands or as close as your mag will allow you to....load 3 rounds each...personally id load 4 each just in case you call a pulled shot... jumping .010 at a time to about .100 off if the case allows you to without crushing powder...so .010 off .020 off .030 off ECT until your at .100 off WITHOUT changing anything else.
you see when you start changing multiple things at once your going to have a hard time figuring out what the problem is so one thing at a time.
i picked the 38.5g load because your 3/10s of a grain on either side and the velocity does not change much so id say thats a pretty stable load and at this point your just trying to figure out if bullets are the problem nothing else.
bring your targets in to 100yds...if a load shoots at 100yds 99% of the time its going to shoot good all the way out...ive only had 1 time a load shot at 100yds and not good at distance...this will also help eliminate shooter error to a point.
once you find a good load at 100yds shoot it at 200 or 300yds if you like to check the load...do not take this wrong but looking at your groups at 300yds im going to guess you are most of the problem not the gun or bullets...again do not take that wrong im just being honest with what i see on paper...the ONLY decent group i see is the 39.5g load at .060 off the lands but yet i see 1 round approximately 2" or so off to the right.
thats said my suggestion would be to stop shooting load development and or shooting groups to verify a load at 200 and 300yds because the smallest movement on your part becomes a huge disappointment on target...i know because ive been here myself.
i would take your 38.5g load and run a seating test starting at .010 off the lands or as close as your mag will allow you to....load 3 rounds each...personally id load 4 each just in case you call a pulled shot... jumping .010 at a time to about .100 off if the case allows you to without crushing powder...so .010 off .020 off .030 off ECT until your at .100 off WITHOUT changing anything else.
you see when you start changing multiple things at once your going to have a hard time figuring out what the problem is so one thing at a time.
i picked the 38.5g load because your 3/10s of a grain on either side and the velocity does not change much so id say thats a pretty stable load and at this point your just trying to figure out if bullets are the problem nothing else.
bring your targets in to 100yds...if a load shoots at 100yds 99% of the time its going to shoot good all the way out...ive only had 1 time a load shot at 100yds and not good at distance...this will also help eliminate shooter error to a point.
once you find a good load at 100yds shoot it at 200 or 300yds if you like to check the load...do not take this wrong but looking at your groups at 300yds im going to guess you are most of the problem not the gun or bullets...again do not take that wrong im just being honest with what i see on paper...the ONLY decent group i see is the 39.5g load at .060 off the lands but yet i see 1 round approximately 2" or so off to the right.
Thanks, the rifle is nothing special, but it's a step up from the factory rifles I've used in the past.
I can certainly blow a group, but I shoot at range weekly, have for a while and have a pretty good idea of what par looks like for myself. It's uncommon for me to blow groups like that... and it's not every group. I was doing much better with my Cross hunting rifle on the same trip stacking them on the 300 yd silhouette's forehead, so I don't even think I was particularly off my game those days. I appreciate where you're coming from, but I don't think that is the problem in this particular case. I'd also add that I just put this rifle together, but I've had others in the past that I had set up for similar uses like my RPR and CTR that I never had this kind of inconsistency with. Coupled with the weird seating feel and neck tension issues, that's why I started looking around, called PVA and posted the question up here.
To follow up, I have gotten a micrometer out and measured some of my 112gr Match Burners, 105gr Match Burners and 108gr ELDs, and I think this is the problem:
112gr Match Burners
Shank diameter: 0.2430"
Pressure ring diameter: 0.2439"
108gr ELD
Shank diameter: 0.2430"
Pressure ring diameter: 0.2430"
105gr Match Burners
Shank diameter: 0.2435"
Pressure ring diameter: 0.2436"
Those numbers are pretty indicative of the few bullets of each type I measured, some of the 105s have a difference of up to 0.003" or so, but only the 112gr are nearly a thou over.
I also played with repeatedly resizing and seating 112gr, 108gr and 105gr, and trying to push them into the case to get an idea of bullet grip. The 112gr is the only one I could consistently push into the case with reasonable effort, by hand with the shorter OALs, and pressing against the table with minimal force at any OAL... 108gr and 105gr did not budge, same cases, same neck collet.
I talked to a Barnes technician on the phone today for a while and they asked for pictures of my lot numbers, so we'll see. For now, I suspect that Josh from PVA was right about the source of my issues, so I'm going to move on and work with the 108gr ELDs next.
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I personally had a spectacular 112 mb failure at the AZ 2 day match. Had a roughly 30% explosion rate from the jackets separating. I'm not sure if it was the heat (112°), or what but 2850 fps and a 7.5 twist should not have led to them poofing. I could have had a fucked up lot I don't know.
Not sure which portion of the number at the bottom is the lot number, or if it's the whole thing. The box on the left is one I've used up at this point, but the other two both measure the same.
I've measured maybe 6 or 7 between the boxes and they all measure between 0.2438" and 0.244 at the pressure ring.
Just curious, anything particular about the GT that didn't work out for you for Benchrest, or just on to something else?
May want to pay for a full membership before posting for sale ads as it’s a good way to get banned.
Also, this isn’t the PX.
Also, this isn’t the PX.
I don't think the geometry of the gt in 6mm is quite as efficient/accuracy pedigree as the BR cases adaptations. However there are a few running a 6.5gt variant and it's given great benchrest accuracy. It boils down to case capacity to bore ratio, using the fastest available powder burn rate to achieve your desired velocity nodes.
I measured the pressure ring on 10 bullets from two different batches of the MB 112's. The first 500 count box is the one I've been shooting and have had some difficulty getting consistent groups in my Dasher. I'm not really sure which thread to keep that data in, though. I've posted it here which is specific to the 112's.
Iv heard about a couple of bad batches of the 112 burners due to a enlarged pressure ring could be part of the problem
Started breaking in my new MPA 6GT this past week. Worked up a generic load and damn does it just shoot nice.
0x (GAP)Hornady brass neck turned
Cci400 srp
36.0gr h4350
105gr hornady bthp
Cbto 1.940" with 0.050" jump.
Average speed using magnetospeed v3 2853fps
Zeroed my rifle at 100 yards, set zero stop and was cleaning every couple rounds. 10 round group with a sighter. Have another 40 rounds loaded and once I've run through them I've loaded up some 108gr eldm to do a ladder test. I will post results.
0x (GAP)Hornady brass neck turned
Cci400 srp
36.0gr h4350
105gr hornady bthp
Cbto 1.940" with 0.050" jump.
Average speed using magnetospeed v3 2853fps
Zeroed my rifle at 100 yards, set zero stop and was cleaning every couple rounds. 10 round group with a sighter. Have another 40 rounds loaded and once I've run through them I've loaded up some 108gr eldm to do a ladder test. I will post results.
I was out breaking my barrel in and decided to see how my 6GT handled 500 yards with a 12-15 mph crosswind. My vertical spread was about 1/2" and my horizontal was about 2-1/2" or less. I was running 105gr hornady bthp at 2853fps. I am working up a load with 108gr ELDM's H4350 and Hornady brass that will do even better. I will post my load workup once I have dialed it in.
You'll likely find best accuracy 2900-2920 or just up on the top side of 3k. That 3k velocity node may be warm/hot in your rifle with Hdy brass.
