Load data doesn't match results IRL

[STINGRAY1979]

Hello, and thank you all for allowing me to join! I've been a fan of this page for quite some time and has helped me through some quandries in the past. Ive got an issue ive spent the last roughly 5 years trying to figure out.

Learned reloading from my dad. better part of 40 years worth of helping him and learning. Reloading on my own for approximately the last 6 years. We'd always used the Lyman bible and worked up loads using that. My dad never had a Chronometer and never knew the velocities. Simply went with data from book, and went with whatever load within what the book said, was most accurate.

It wasn't unti lI started doing my own reloading, a bit more financially secure, and wanting to be more high tech, that I got a chronometer and use it whenever I do load workups. But this is when things started to go off the tracks. I have found that real life data isn't matching, or even coming close to what the bibles say. So, I got the Hornady bible. Lyman and Hornady seem to be in different worlds, as the data between them isn't even close for what I reload. (.223, 9mm, 45-70 Govt, 6.5 CM, .357 Mag) Lyman has charge weights WAY above what Hornady says typically. So, this is when I brought in a 3rd source. I typically use Hodgdon powders, and therefore use their load data. Again, sometimes WAY different than Lyman and Hornady. So, then I got Quickload program. A bit of a learning curve, but I got it and find it to be more accurate in predictions than the bibles typically are.

This is where my question comes in. Using my .223 Rem load data...
Rifle: Ruger AR556 MSR
18" barrel Direct Impingement
1:8 5R rifling
Miculek Comp
No modifications
Lyman data says: test barrel from Colt AR-15 20" barrel, 55gr Jacketed SP and H335 at 24.3gr should be hurling the freedom seed at about 3150fps. Hornady says 23.2gr should get 3100fps, same barrel length. Hodgdon says, 23 grains at just over 3000fps, but their twist is 1:12 and 24" barrel. QL shows it should be doing 2650fps.
MY real data taken by a Chrony shows 23 grains of H335 behind a 55gr Jacketed SP from my 18" barrel 1:8 twist is only doing 2600fps. 80 degree humid Iowa weather. Why? Why the huge difference? I am taking into account for the 2" less barrel length, but not 500fps difference. What am I missing? How can the bibles be so wrong, but QL be so accurate?

My dad must have great confidence in me, as I convinced him to lower his charge weight in his .357 Mag because the velocities were too high. He asked my why the bibles were so different than the real world results. He was really upset he'd been using dangerous load for such a long time. I couldn't answer him. And this has been something I have been trying to figure out for the past 6 years. And now I feel its imperative to find out. Perhaps someone can help me understand. Oh, and BTW, this isn't the only load i've seen these disparities with.

 

[Ned Ludd]

Pressure/velocity as reported by either a reloading manual, or even QuickLoad, should be taken as a guide, not necessarily as gospel. In your specific example, there are some differences that may collectively explain the lower than expected velocity. First, you're running a barrel that is 2" shorter than the reference values. As noted, the barrel twist rates are also different. The manuals don't know the burn rate of your specific Lot# of H335, the case volume of the particular brand of brass you're using, the specific primer, or even how "tight" the bore of the rifle is. Although these items collectively may not seem to fully account for the magnitude of velocity differential you're observing, the fact remains that your velocity was only ~2600 fps, so they must at least be part of the explanation. In this particular case, it seems as though the QuickLoad estimate is far closer to your actual value than the manuals. However, it is worth noting that even the values reported in the manuals differ by as much as 150 fps.

FWIW - I always "calibrate" QuickLoad files for a given setup/rifle by obtaining an average velocity for at least 5 rounds using a slightly reduced load for safety reasons. All the required measured values (barrel length, case trim length, bullet OAL, case volume, COAL, temperature) are input into the program using the factory preset burn rate (Ba) for the specific powder used. Then the Ba is then adjusted until predicted velocity matches the actual measured average velocity. At this point, the program has been "calibrated" to the given setup and predictions should be reasonably good within a given charge weight range. If the final charge weight selected is too far away from that used for the "calibration" velocity reading, it will likely be necessary to re-adjust the Ba with the new charge weight (i.e. re-calibrate the program). I believe this is because QuickLoad treats many of the responses/outputs as linear, but they are not always linear.

As another thought about why the manual values might be so different from real world results, just take a look at the number of variables involved in setting up a QuickLoad file as an example, which you have already done. There is no way a manual can realistically take all of these variables into account. Different cartridges, powder burn rates, primers, case volumes, bullet weights, etc., make it very difficult even for the reloading program to make exact predictions without some tweaking to account for differences between user setups. Nonetheless, I agree with you that a 500 fps difference seems larger than it should be. This may be a case where several small differences collectively account for the discrepancy. I should also note that the differential between the QL prediction and your actual velocity is only 50 fps. So in this case, it may also be that the velocity values reported in the manuals are overly generous, and that the QL prediction is more realistic and closer to the actual velocity than the manuals. I would stick with the QL outputs in this specific case.

 

[Oso]

As Ned said… minor variances can add up. Primer, case volume / case fill, neck tension, bullet crimp, bullet jump.

We get used to think of components as constants…. Use same powder and brand of primer then no difference, when in fact there are differences from batch to batch (lot to lot).

Each rifle will shoot the same cartridge differently. Two identical production rifles with consecutive serial numbers may behave differently (variations in velocity and accuracy).

Load Manuals are guidelines. Start low and build up.

 

[rebeltex]

223 data in a 556 chamber?
556 longer throat may make a difference.

 

[STINGRAY1979]

223 data in a 556 chamber?
556 longer throat may make a difference.

Yes. .223 in 5.56 chamber

I'd also like to add that just recently I developed a load for my .357 mag. Fired from a GP100 6". 158gr seed, 16gr H110, CCI 550. In m y GP100 it does 1250fps. Dad's Python, 6" its doing 1432. How? really that much difference from gun to gun? 200 fps?

 

[PigButtons]

Four minor points to consider with the AR numbers: 1 ) The Colt barrel was possibly chrome lined. 2 ) The Colt barrel was definitely not 5R. 3 ) The 20" Colt barrel may have been a rifle length gas system. 4 ) Not all 55gr Jacketed SP are created equal, jacket material, flat bottom vs boat tail, etc.

Some of these factors could make it slower, some faster, but in the long run only testing can answer these questions.

 

[Doom]

Most of the data you reference is from test barrels not actual guns. These have minimum sized chambers. Typically commercial chambers are larger than minimum and often have longer freebore. In the case of H335 you should be in the 24.5 to 25 gr range. Be very careful in that hot Iowa sun if you go much above 25 gr. That powder is temperature sensitive. A locked up bolt is no fun.

As for the revolvers, there is clearance between the cylinder and forcing cone that allows gasses to escape which can result in different velocities. Also the same comment applies to the chamber in that the chambers may be different.

 

[Pawnee Bill]

You don't mention anything about how accurate the loadings are. Is accuracy your goal or just fast loads? The two don't usually go together.

 

[STINGRAY1979]

You don't mention anything about how accurate the loadings are. Is accuracy your goal or just fast loads? The two don't usually go together

the .357 is same hole at 17 yds. .223 is 1.5 MOA. The purpose of my inquiry is that the loads are falling in line with what the resources (Lyman, Hornady, Hodgdon, QL) are telling me. Looking for signs of overpressure but not seeing it. When Im only dealing with 30k psi, not going ot see them anyways. Its more of trying to understand why such a large descrepancy between resources and real life. Trying to find a pin point answer. See how far I can push the loads. I really don't want one to blow up in my face just to find out. If I can pin point a reason, then perhaps I can figure for it and compensate. But it seems to be random. Just my perspective.

 

[Webster]

You don't mention anything about how accurate the loadings are. Is accuracy your goal or just fast loads? The two don't usually go together.

I always go for accuracy. I don't care what the velocity is as long as it's reasonable. Always above 3550 in my 6BR & 6BRX with safe pressures. Shooting the 6BR for 11 years long case life.

 

[Jager]

As mentioned by a bunch of fellows up thread... load data sources will often vary quite a bit from each other. That's one reason why depending upon a single data source is rarely a good idea. The ideal is to find general consensus across multiple load sources. When you don't have consensus... tread extra carefully.

QuickLoad, calibrated carefully as described by Ned Ludd, is an excellent resource. It's particularly valuable because it gives you insight into your chamber pressures. Once you're confident you can model it properly, it can save you a lot of time and components.

That said, something is amiss with what you're describing. When I input your 24.3/H335 load drawn from the Lyman manual, using a Sierra 55gr SPBT, and coming from an 18" barrel such as on your Ruger - all other factors in QuickLoad left at their defaults - it predicts 2902 fps and 45K psi chamber pressure.



I'd suggest not putting too much faith in the results you're getting from your Chrony until you can validate its numbers with another chronograph; or verify it's in the ballpark with a factory load of known performance. And if you're seeing the same 2600ish print from QuickLoad, something is wrong with that. You need to figure out what that is before making load decisions based on it.

 

[rebeltex]

Jager,
223 in a 556 chamber, pressures are different.

 

[Jager]

Jager,
223 in a 556 chamber, pressures are different.

5.56 Nato chambers are rated at a slightly higher pressure but cartridge and chamber dimensions are essentially identical. The longer throat in a 5.56 chamber isn't going to make any meaningful difference.

QL shows the above 24.3/H335 load making 16 fps more velocity in a 5.56 Nato chamber.

 

[Bronsin]

I have only ever had one instance where my rifle matched the book. The Hornady manual used a M70 to test loads for the .243, and I have a M70 in .243. Powder for powder, and bullet for bullet, those loads match. Nothing else ever has.

 

[Webster]

Hello, and thank you all for allowing me to join! I've been a fan of this page for quite some time and has helped me through some quandries in the past. Ive got an issue ive spent the last roughly 5 years trying to figure out.

Learned reloading from my dad. better part of 40 years worth of helping him and learning. Reloading on my own for approximately the last 6 years. We'd always used the Lyman bible and worked up loads using that. My dad never had a Chronometer and never knew the velocities. Simply went with data from book, and went with whatever load within what the book said, was most accurate.

It wasn't unti lI started doing my own reloading, a bit more financially secure, and wanting to be more high tech, that I got a chronometer and use it whenever I do load workups. But this is when things started to go off the tracks. I have found that real life data isn't matching, or even coming close to what the bibles say. So, I got the Hornady bible. Lyman and Hornady seem to be in different worlds, as the data between them isn't even close for what I reload. (.223, 9mm, 45-70 Govt, 6.5 CM, .357 Mag) Lyman has charge weights WAY above what Hornady says typically. So, this is when I brought in a 3rd source. I typically use Hodgdon powders, and therefore use their load data. Again, sometimes WAY different than Lyman and Hornady. So, then I got Quickload program. A bit of a learning curve, but I got it and find it to be more accurate in predictions than the bibles typically are.

This is where my question comes in. Using my .223 Rem load data...
Rifle: Ruger AR556 MSR
18" barrel Direct Impingement
1:8 5R rifling
Miculek Comp
No modifications
Lyman data says: test barrel from Colt AR-15 20" barrel, 55gr Jacketed SP and H335 at 24.3gr should be hurling the freedom seed at about 3150fps. Hornady says 23.2gr should get 3100fps, same barrel length. Hodgdon says, 23 grains at just over 3000fps, but their twist is 1:12 and 24" barrel. QL shows it should be doing 2650fps.
MY real data taken by a Chrony shows 23 grains of H335 behind a 55gr Jacketed SP from my 18" barrel 1:8 twist is only doing 2600fps. 80 degree humid Iowa weather. Why? Why the huge difference? I am taking into account for the 2" less barrel length, but not 500fps difference. What am I missing? How can the bibles be so wrong, but QL be so accurate?

My dad must have great confidence in me, as I convinced him to lower his charge weight in his .357 Mag because the velocities were too high. He asked my why the bibles were so different than the real world results. He was really upset he'd been using dangerous load for such a long time. I couldn't answer him. And this has been something I have been trying to figure out for the past 6 years. And now I feel its imperative to find out. Perhaps someone can help me understand. Oh, and BTW, this isn't the only load i've seen these disparities with.

With my two rifles I get load data from 2 or 3 manuals. I use commonly available powders. Start about two grains of powder below what looks like a max charge in the books. Shoot ladder test and judge pressure by looking at primer crater size, ejector swipe marks or bolt lift stiffness. Any of the three I back off. It's worked for me for 50 years of reloading. Don’t know anything about pistol reloading. If you look at the primer crater indents after a ladder test you can clearly see the indents getting bigger with each powder increase and you will develop a feel for when the pressure is getting pretty high. Never got the ejector holes bushed tight to save money and keep my pressure indications. Both of my GH hunting rifles are Rem 700 with a lot of money in them. Never cared for QL. It might give pressures and fps but I don’t see how the results relate to accuracy. I develop loads by looking at the group size and shape. It isn't difficult if you are careful and pay attention to details. It helps to have a rifle that shoots just about any load under ½”.

I was involved with materials qualification of bar stock of about 20 alloys coming into the plant, production quality auditing and metallurgical failure analysis for 45 years. Also performed mechanical testing of carbon steel alloys for 9 years. May not be the smartest kid on the block but I was very good at what I did. I seem to have an obsession for details and not general statements. Don’t want to seem like I am bragging but some people on this website that didn’t know what they were talking about insulted my opinion on a few things. Had to get this off my chest.

Happy Shooting!

 

[Jeff Porter]

Welcome to the addiction. What chronograph are you using ? What powder measure system are you using ? How do you store your powder ?

 

[Dave M.]

I always go for accuracy. I don't care what the velocity is as long as it's reasonable. Always above 3550 in my 6BR & 6BRX with safe pressures. Shooting the 6BR for 11 years long case life.

3550fps in a 6BR??? I don’t think so sir. Likely not even 3000fps from a 6BR

 

[Webster]

3550fps in a 6BR??? I don’t think so sir. Likely not even 3000fps from a 6BR

58 and 60 gr bullets. Have shot a few at 3620. Over 3700 with my 6BRX 58 gr bullets.

 

[Dave M.]

58 and 60 gr bullets. Have shot a few at 3620. Over 3700 with my 6BRX 58 gr bullets.

I was thinking you were shooting longer range and were using a 95+g bullet.

 

[Rsadams]

I have never had a load perform like the reloading manual said it was supposed to...