Barrel time, based on Quickload

[calgarycanada]

Hello
In my previous thread I asked for some help related to 215 Hybrids in 308 rifle. I couldn't get it to shoot consistently, you guys suggested bunch of things to try. I tried them all/most and nothing seemed to help. Finally I broke down and ordered Quickload. After playing with it for few hours it looks like I'm not even close to node/barrel time based on calculations. It is only software and can't predict everything but it can't be that far off. For example, I found optimal barrel time/node for 30" barrel are at 1.520ms or 1.345ms(achievable in 308).
I read as many threads as I could find online(how much can I trust internet?) and people seem to have success with this combo around 2500ish fps or 2630ish fps. I was getting decent results around 2495fps which is close to most others and barrel time(according to quickload) is around 1.47ms so technically not in node. Other velocity folks are having luck with is 2630, barrel time of 1.362ms which is getting close to node, maybe software is off by a little, so possibly good node right? But catch is predicted pressure is 69090 psi . If we were to assume Quickload is correct(spot on), lower node velocity will be around 2430 fps(disappointing), give or take depending on powder used. Higher node velocity will be around 2707 with pressures of whooping 76000+ psi, only two powders that can be made to fit in this case will be RL 17 or IMR 4007ssc. Powder burn rate etc can have some effect but it can't be that far off?

So questions that are driving me nuts are
Are most of the claims on internet wrong, about 2500 or 2630 fps nodes?
If those velocities are working for some, are they running out of node and having success?
Is there a way to tune rifles when load is not spot on in node?
last but not least, most if not all are running overpressure or is Quickload built lawyer safe?

Thanks in advance
Av
BTW I'm new to quickload so maybe I'm screwing up data entry, so I'll add my inputs here if somebody wants to double check numbers
Barrel length 30 "
Bullet length 1.572"
Seating depth 3.050"
H2O capacity 56ish grains average(fired cases)
Powders I have on hand, H4350, IMR 4007ssc, H4895, Varget, Rl 17. I prefer to use H4350 or IMR 4007SSC or H4895.

 

[nastynatesfish]

Try 4007. I was running 48+ gr in my ftr 308 with 175s and it was running them 2945fps with lapua lo brass and no pressure

 

[fguffey]

It is only software and can't predict everything but it can't be that far off. For example, I found optimal barrel time/node for 30" barrel are at 1.520ms or 1.345ms(achievable in 308).

I purchased a rifle, it was decided by reloading forums to the ugliest, the more kind ask "What was he thinking?". I was thinking no one could build a rifle that ugly without knowing something about what they were doing, so I bid and won the auction. $120.00 for parts but on the outside chance the builder knew what he was doing I took the rifle to the range, 12 different loads of 10 rounds each using different cases, bullets and powder. There was nothing I could do to improve accuracy so I applied the 'leaver policy', I left-er the way I found-er. Some of the groups moved but never opened up, some shared the same hole.

The rifle had a trigger that cost almost as much as I paid to win the bid, I installed a scope, mount and rings that did cost more than the rifle.

F. Guffey

 

[wolley]

QL seems to have some inherent errors. I.E my Palma load per QL is 2980. My Chrono shows it at 3058. My come ups match the 3058 velocity much better than the 2980. I can fiddle with the weighting factor to get the velocity to match but the pressure drops 4,000psi. My brass says the pressure is much higher. 2-3 reloads is it at this velocity.
Now that I've prefaced that I will say that QL is extremely handy. One thing I do with it, is using a known accurate load I can run it through QL and get the barrel time. I then take that number and substitute powders or bullets and shoot for the same muzzle time. 9 times out of 10 I can take that load to the range it will be very accurate.

 

[CharlieNC]

Increasing your freebore may give you some pressure relief; this dimension is not directly accounted for in QL. You can also run some cases using lighter, lower BC bullets to see if the predicted higher velocities put you into a better ballistic combination. My 308 short throat Savage was pressure limited and I came out ahead with 155 palma vs 175 smk based on QL barrel times and confirmed shooting by reaching a higher charge node.

 

[waldo1979]

QL seems to have some inherent errors. I.E my Palma load per QL is 2980. My Chrono shows it at 3058. My come ups match the 3058 velocity much better than the 2980. I can fiddle with the weighting factor to get the velocity to match but the pressure drops 4,000psi. My brass says the pressure is much higher. 2-3 reloads is it at this velocity.
Now that I've prefaced that I will say that QL is extremely handy. One thing I do with it, is using a known accurate load I can run it through QL and get the barrel time. I then take that number and substitute powders or bullets and shoot for the same muzzle time. 9 times out of 10 I can take that load to the range it will be very accurate.

If your velocity numbers are off then Quickload needs to be tuned. Lot to lot burn rates are often attributed to these variances. There are a couple articles out there on how to tune Quickload. Generally this involves ensuring an accurate case volume, modifying the burn rate value, or just tweaking the bullet weight by a grain or two.

I noticed that Varget and reloder-15 are pretty spot on but vihtavuori powders are a little off.

 

[Joe R]

calgarycanada,
Have you read Chris Long's paper on Tuning QuickLOAD to achieve best results? What twist is your barrel?

Below is the paper you need to read.

Joe

 

[XTR]

I can't tell you anything about quickload, but I can tell you what happens if you start trying to get 2700FPs with 215s in a 308. You get as many uses from Lapua Palma brass as from the primers. That is an expensive experience.

I highly recommend you don't go there.

In 2012, once I figured out that single use brass was not for me I got a really good 215 load that was running about 2450, (my ES was in the range of 9 on my low quality chrono) which seems to match up with your predicted node. I never tried it any faster, and I dropped the 215 project because I couldn't control the recoil.

Another thing to consider is that reloading on the internet and reloading IRL are quite different.

 

[dcali]

I just went through this today with the 215's in a new barrel. After a near heart attack when the first two rounds landed 4 MOA apart, things settled in and a stout load of Varget got me up to about 2580 out of a 32" barrel. Although the brass looks fine, according to QuickLOAD, it's pushing things, but not outrageous. I hesitate to mention the load because it will be hugely overpressure in the wrong chamber.

I'm an OBT heretic (don't believe in it), so I won't comment on that. But what I have learned so far:

1) Velocity SD's dropped as pressure went up.
2) Accuracy is better jumping 15-20 thous than right at the lands no matter what the load
3) I'm worried about my brass life at these pressures. Palma brass may be on my list for next year.
4) 215's ain't no 6XC. Recoil control matters. It's not a setup for novices, who will struggle to tell a bad load from a bad position.
5) The faster I push it, the more accurate it gets.
6) I have a hunch that if I put another grain of powder in, I'd have an absolute hammer. But I don't think that would be wise.

Vibrations are more of a factor with a 32" tube than a 22" tube, and when you add heavy bullets to the mix to drive those vibrations, they just get temperamental. It's not that the recoil is so bad on an absolute scale, but combined with the noodle barrel, everything has to be just so to work. Throw in that long bullets are more sensitive to imbalance, and you have a challenging situation. But that BC...

 

[CPorter]

Checking Chris Long's optimal barrel time calculations I find your nodes to be at 1.63ms and 1.53ms. At 1.52ms the fastest velocity is 2502 fps using 41.8 grains reloader 17 and a 2.800" OAL. It is a compressed load. The pressure at that load is supposed to be 52,926 psi.

At 3.050 OAL the velocity goes to 2545 fps with 44.6 grains RL 17 at 98% case fill and 51547 psi.

Trying to hit the next node (1.33 ms is dangerously over pressure rating for the brass.

 

[Terry_M]

calgarycanada,
Have you read Chris Long's paper on Tuning QuickLOAD to achieve best results? What twist is your barrel?

Below is the paper you need to read.

Joe

Thank you very much for posting this. and thanks OP for asking the question.

 

[Keith Glasscock]

First, let me say that I have met Chris, and he is a real-life genius. If you talk to him long enough, there are nodes between his predicted nodes. Those nodes tend to be, in my experience, narrower and a little more touchy than the predicted ones.

Now, the funny stuff: Has anyone looked into the most touted load for 284 win in a 32" barrel? I'm talking about H4350 at 2800-2825 fps. If you run that through QL, you'll get a barrel time half way between the predicted nodes. The funny part is that this one shoots and shoots well with great consistency.

If you look at Chris' original white-paper, you will notice that his first predictions were done visually for a 30" barrel. The surprise is that the calculated barrel times differ a little from those numbers. Want to bet which set shoots best?

All-in-all, Chris' work is quite valuable when trying something new, but its usefulness is limited by inadequate tuning of QL to one's barrel and lot of power/primers. The first step in finding a load is a chrono session while doing the workup of charges to find max.

On another note, I've found that the Varget profile in QL is not even close in a 308 regardless of barrel (I've got 3 right now) and powder lot. The same lots of powder are dead-on with QL predictions in a 223.

 

[XTR]

If you are shooting 215s at an OAL of 3.050 you should to look into another .075 or more of throat. That OAL still leaves a lot of bullet in the case.

 

[calgarycanada]

Let me try and answer few questions that came up

I'm using 1-9 twist Benchmark barrel

I have thought about extending my OAL. I'm gonna try tuning to lower node(2500-2550) and if I cant, gun will go back to gunsmith for little tune up including extending throat.

In no way I'm trying to get to 1.345ms/2700 fps load with 308+215s, I just said they are achievable in 308(higher node with lighter bullets of course)

If I can at all, I don't wanna use RL 17 coz of its sensitivity to temperature change, we get big temperature swings from morning to afternoon. I have seen as bad as 30 degree Celsius change from 7 am to 2pm(-17 C to +14 c).

The reason behind this question was, if barrel times matter that much and nodes only exist at those barrel times, how can so many shooters be successful at 2500fps, 2550fps and 2630fps with this combo?

As mentioned above, there must be other nodes in existence coz most loads for 180 grains hybrids in 284(& shehane) don't match any of the barrel times in Quickload, unless of course if QL is that far off in predicting barrel times. That is what I was wondering about,(again) is QL that far off or is there other nodes as well that are not mentioned in that paper?
Actually Bryan Litz was generous enough to reply to my PM and he also said to not worry about any barrel times and see what gun tells you and more then likely it's not that I can't find a node but it's possible that I'm not consistent enough with these heavy bullets or setup is not consistent, which I totally believe.
So it's time to work on my position and setup and then test some more. Fun fun!

 

[dcali]

The reason behind this question was, if barrel times matter that much and nodes only exist at those barrel times, how can so many shooters be successful at 2500fps, 2550fps and 2630fps with this combo?

Barrel time does matter - but it's not simple, and there is a heck of a lot that goes into it. It's not just the barrel that matters. How the barrel is attached to the action, how the action is attached to the stock, how stiff the stock is, how the stock is held, how much your scope weighs, etc - all of these things impact the barrel vibrations. It's not surprising at all that different shooters find different loads even for rifles with nearly identical barrels. It's also not surprising that they tend to be close but not perfect. Just the way it works. Don't get wrapped up in trying to predict this stuff. I used to be a structural dynamicist that did this all day long for a living. Trust me when I sat you cannot predict this stuff with the accuracy we need without some very sophisticated software and careful testing. It's just too complicated.

 

[calgarycanada]

The reason behind this question was, if barrel times matter that much and nodes only exist at those barrel times, how can so many shooters be successful at 2500fps, 2550fps and 2630fps with this combo?

Barrel time does matter - but it's not simple, and there is a heck of a lot that goes into it. It's not just the barrel that matters. How the barrel is attached to the action, how the action is attached to the stock, how stiff the stock is, how the stock is held, how much your scope weighs, etc - all of these things impact the barrel vibrations. It's not surprising at all that different shooters find different loads even for rifles with nearly identical barrels. It's also not surprising that they tend to be close but not perfect. Just the way it works. Don't get wrapped up in trying to predict this stuff. I used to be a structural dynamicist that did this all day long for a living. Trust me when I sat you cannot predict this stuff with the accuracy we need without some very sophisticated software and careful testing. It's just too complicated.

That's the conclusion I have come to. QL is nice to have but not good for what I was thinking of doing. Learned my lesson

 

[XTR]

I think QL probably gives very good predictions of pressures if you put in the right info. The barrel tine nodes may or may not be of particular value, your targets will tell you that.

That said...

I don't own QL yet, and not sure if I'll get it any time soon, but when you consider that in competition shooting today people are loading super heavy for class bullets seated way beyond the OALs that the manuals are built around and burning powders that were never considered for those calibers. Then I think for a lot of what we are doing in competition shooting today, the ability to input actual parameters and get a reasonable estimation of pressure is in itself is of great value.

 

[dcali]

I think QL probably gives very good predictions of pressures if you put in the right info. The barrel tine nodes may or may not be of particular value, your targets will tell you that.

That said...

I don't own QL yet, and not sure if I'll get it any time soon, but when you consider that in competition shooting today people are loading super heavy for class bullets seated way beyond the OALs that the manuals are built around and burning powders that were never considered for those calibers. Then I think for a lot of what we are doing in competition shooting today, the ability to input actual parameters and get a reasonable estimation of pressure is in itself is of great value.

This has been my experience so far. I put off buying QuickLOAD for a while, and finally pulled the trigger last month because so much of what I shoot these days is weird - things like a .30 BR or F T/R with 215 and a ridiculous OAL. I just wasn't comfortable with the manuals, which generally don't have what I'm asking for. They're also a few years behind the cutting edge, it seems. I'm sure there will be a .308 (F T/R) section in the next edition of whatever loading manual, but I need info now.

Getting a sense of what effects pressure and by how much has been more valuable than getting exact numbers. I once had a college professor who had some wise words - "We analyze for insight, not numbers." I think that applies with QuickLOAD. You can answer questions like "What are the tradeoffs of a very long throat for 215's only vs a throat that's a compromise between 185's and 215's?"

 

[calgarycanada]

I've developed a number of loads for different rifles/calibers through careful and methodical testing that shot very, very well. This was long before I purchased a copy of Quickload. When I ultimately ran the numbers in Quickload for those loads, lo and behold they were very close to the OBT. Typically, they tend to be just a tick slower (higher barrel time) than the OBT nodes listed in Chris' table. For example, the most achievable OBT node for a .308 30" barrel is listed at 1.3684 ms. My best loads tend to calculate out to be in the 1.372 ms range, slightly slower than the values in the table. Although it is possible to achieve the next higher node with lighter bullets (I'm using 185s), after playing around with the numbers for some time, I've come to the conclusion that safely reaching the next higher node with 185s will be virtually impossible with my setup.

The table on Chris's paper that I found says 1.345ms OBT for 30" barrel, not 1.368ms. Is there any other place where other OBTs have been mentioned?

 

[Joe R]

gstaylorg,
That is some excellent shooting. I shoot with that kind of consistency only in my dreams.

Kindest regards,

Joe