308 load with IMR4064

[newton]

I am hoping some of you seasoned 308 shooters can give some insight to some chrony results I got from yesterdays trials.

Here is a link to the chrony data I recorded.

It's not a cast boolit load, but I know a good amount of you also shoot jacketed rounds right? I am going to be working on a cast load after I get the jacketed one ironed out, but I only chrono those for fun. I chrony the jacketed ones to see how the loads are developing and as a saftey measure.

So, the details of the load are that I am using Sig brass, Fed210 primers, IMR4064, and 165gr nosler BT's at 2.825" OAL.

The powder charges are listed at the top of that page in the link. What is interesting to me is the velocity of shots 5-9. There is a spread of 2 full grains of powder across that range. Just very interesting to me.

On a secondary note, I was not shooting for group with these, just using the target as a point of aim, but the shots all ended up being pretty close. Here is a picture.

Any insight would be helpful.

[MT Gianni]

Shot number one seems to be an anomaly. I would expect the best accuracy to be around loads 9-10 IME. Was your bbl heating up during the testing?

[Norske]

If you use a chronograph, you will find your first shot is noticeably slower than following shots. That's because some of the energy is being used to heat the chamber and barrel interior. For hunters, it's a problem because the odd shot is their most important one.

[country gent]

Shot number 1 may be a clean cold barrel giving the results it did. I would say to test a 10 shot group at load 7 and a 10 shot group at load 12. these are the points where 3 shot clustered close.

[newton]

Thanks guys.

I guess more info from me would be helpful.

On the chrony data, up at the top, you will see where my notes are. I list what each shot was. Shot #1 was a test round from a box of Hornady Whitetail ammo, 150gr. The following shots you can see exactly what I loaded powder wise. All the rest of the load - brass, primer, bullet, oal - is the same.

Here is where it gets sketchy. Like you country gent, I also saw the results of them grouping together. I honestly was not looking for how they grouped, this test was just to check velocity and pressure signs. I only had loads 2-9 at the bench. I am waiting for a new scope to arrive, so in the meantime, I am using an older scope that is not ideal for target work.

However, after I shot load #9, I started wondering what going on up to 45gr might do. I was really wanting to hit the 2700fps mark and I hadn't really seen any pressure signs that made me think to stop. I went back to the bench, loaded up the 45gr and saw it land right there where it did and decided to load three more up just to do a simple group test. So those three shots you see down in the lower left-hand corner is the 'group' test of 45gr.

But, kinda after the first shot(#11), but most certainly the second of the three(#12), I noticed the bolt lift getting a little heavier. Not super heavy, it did not require me to force it, but shot #12 produced a shiny extractor swipe. I went ahead and shot #13, just to see, and I got the somewhat heavy bolt lift, but no swipe. It could be me just being paranoid, because I have never really had a heavy bolt lift in a gun before so I do not know what one feels like for sure. I just know it felt heavier than before. Also, there is a slight - very slight - primer cratering. I know from experience this can come from a number of factors. The cratering is nothing like what I have seen before, and can only be seen under certain light conditions.

So I am going to hold off on that higher end load for sure. I like the velocity, I like the group, but it's not worth it to me to risk overpressure. I really wonder what quickloads would say about that load. I need to get that program one day....

The reason I am posting is I am really curious about the flat-lining of the velocity there between shots 5-9. That is a 2-grain difference in charge weight.

Here is a picture of the shot cases. I wish there was a better way to get pictures, I suppose that taking a picture of each one individually might get better resolution.

[newton]

Shot number 1 may be a clean cold barrel giving the results it did. I would say to test a 10 shot group at load 7 and a 10 shot group at load 12. these are the points where 3 shot clustered close.

And yes, the first shot was a clean cold barrel.

[MostlyLeverGuns]

Did you notice any difference in the bolt lift from your factory loads and the 45 grain load? Do the fired/empty cases from the 45 gr load chamber easily? I use the ease of chambering a case after firing as another observation of pressure. If cases chamber fired cases chamber easily, pressure is not usually beyond safe limits. Nosler does list 44.5 gr as max in their manual, Hodgdon has 46.3 for a 165 Hornady. 2700 with a 165 is about as good as you can get from the 308, barrel length, case capacity can change things a little but I think you are at Max or 'max+' using 4064. Reloder 15 or Varget might get a little more. I have used Reloder 15 with very good results in several .308 Savage 99's. IMR4064 is an old standard that does well. I used up 8 lbs in a 300 Savage with 150's.

[newton]

Did you notice any difference in the bolt lift from your factory loads and the 45 grain load? Do the fired/empty cases from the 45 gr load chamber easily? I use the ease of chambering a case after firing as another observation of pressure. If cases chamber fired cases chamber easily, pressure is not usually beyond safe limits. Nosler does list 44.5 gr as max in their manual, Hodgdon has 46.3 for a 165 Hornady. 2700 with a 165 is about as good as you can get from the 308, barrel length, case capacity can change things a little but I think you are at Max or 'max+' using 4064. Reloder 15 or Varget might get a little more. I have used Reloder 15 with very good results in several .308 Savage 99's. IMR4064 is an old standard that does well. I used up 8 lbs in a 300 Savage with 150's.

I think so? I know that's not definitive, but its a new gun. Literally, I have shot less than 20 rounds through it, only 6 of them being factory ones. So I do not have a good idea of the differences yet. I would say though, for sure, it had to have been a little more or else I do not think I would have noticed it.

I really do think, after doing a lot of searching, that the general consensus is when you reach a powder charge velocity plateau then you are generally to the point that pushing it further is going to be overpressure.

I am going to get a brighter light and look the cases over better. Even though I was seated out further than the Nosler data which means I should have been at a lower pressure(slightly), I am now thinking that even the 44.5-grain load might have been overpressure.

Their data was with 24" barrel, mine is a 22" barrel. I am also going to measure case capacity with water to see how it lines up with theirs.

I will try chambering some of the fired cases. I know that even though the bolt lift was a tad heavier, the cases came out of the chamber as easy as any of them.

[country gent]

Another thing that can be helpful when testing loads or a new rifle is to buy a few boxes of good ammo for it. In .308 federal gold medal match comes to mind. Starting the day off fire a 5 shot group with it as a control. ( after a few sessions you know what to expect group velocity and variation wise in your rifle. Then Do the testing if your loads.
I carry this 1 step farther, I have a rws side cock pellet gun and a lot number of pellets. I fire a test group with this over the chrono to verify numbers, then the test group with known ammo. THen the test ammo.

[newton]

I just ran across this. I found it interesting. It came from an article that is describing a lot of different pressure signs.

Increase in powder charge achieves unexpected velocity. (Average velocity will tend to increase by the same number of feet per second per grain of additional powder over the normal operating pressure range. If your next charge increment fails to produce the expected additional velocity or produces too much additional velocity, pressure may be high. Poor grouping usually accompanies this symptom. It is also caused at reasonable pressures by uneven bolt lug contact (lugs need lapping), in which case still further charge increments go back to producing orderly velocity increases and grouping improves. Suspect this last situation if the charge at which the velocity anomaly occurs is in the middle of a published load range. Otherwise, back the charge off 5% from where the issue started.)

I am going to take a look again, but I distinctly remember looking at my bolt before I ever put it in the gun. There was one lug(its a three lug Ruger) that had a chamfer on the locking surface, and the others did not.

I will take some pictures and also test the interfaces with some marker.

[newton]

I did not get to test the interfaces of the bolt lugs and receiver last night, because when I pulled the bolt out something else caught my eye. I still plan to test it anyways.

I did test to see if the fired rounds would chamber fine. They all did. When I pulled them out I noticed more/new shiny ejector swipes on them. I found that interesting, so I tested an unfired case. No ejector swipe on the unfired case.

Pulled the bolt and saw this. Right off the bat I saw that the brass was being shaved off by the ejector itself, not being smeared off by the ejector hole. Two totally different things.

After taking the picture, I noticed the gap between the firing pin and its channel. This explains why I was seeing some slight cratering.

I then took a piece of sized but unfired brass and slipped it underneath the extractor, put a little pressure against the bolt face, and rotated it some. Trying to simulate if the case had expanded against the chamber/something slightly holding it stationary(dirty/rough chamber) while the bolt was being lifted. I got this picture. It's sitting next to the case that had the largest swipe I saw. So clearly the swipes are being caused by a sharp edge on ejector, not because brass is flowing back into the ejector channel.

I was pretty relieved at this point, just knowing that some of the signs I was seeing were not full on pressure signs. I still think that I am at the top end, and probably hotter than I should be simply because of the velocity readings and the slightly heavier bolt lift - even though there could be an explanation other than overpressure for both of those things.

I would dearly appreciate it if someone with Quickloads could run my numbers and tell me what it says. Would be interesting to see at least.

Here is what I know. My OAL is longer than Noslers and my case capacity is more than theirs. Both given to the side of having lower pressure for given powder charges. I think that's why Hodgdon lists even higher max charges because they use Winchester cases which have even more volume inside. That's my theory anyway.

[sfcairborne]

Never could get 4064 to settle down in my 308's. Moved to I4895 and have never looked back. Try 42.5 I4895 it's a solid driver in my 308s

[Wayne Smith]

"My OAL is longer than Noslers" - this might be your problem. If your bullet is into the rifling this will increase pressure even with a larger case capacity. Check your bullet jump and try loading them at Nosler's OAL and see what happens.

[swheeler]

I didn't know Nosler ever gave an OAL in their reloading manuals.

[Larry Gibson]

With just 1 shot per incremental increase in powder charge it's hard to determine anything based on velocity other than the velocity increased as the charge increased.....but we already know that. Problem with a 1 shot test of any load is you've no idea of the ES of that load. Therefor you've no idea if the recorded 1 shots velocity was in the top end, the bottom end or the middle of the velocity ES for that load.

Basically your target is a representation of the oft misused Audette Ladder as a means of load development. Since the method is misused it really tells you nothing because you have no idea of the cone of fire (group potential) of any load. Ergo, not knowing the size of the group you've no idea where in the cone of fire that bullet went.

If you want a hunting load I suggest testing 3 five shot groups of loads 7 through 11 looking for the best accuracy. That will give you the best of both velocity and accuracy for hunting.

If you're looking for a target accuracy load then test ten shot groups of loads 4 through 7 as accuracy is the name of that game.

Back in the day IMR 4064 was a favored powder for loading 3.08W match loads with 168 MKs. The standard load was 42 gr.

[newton]

"My OAL is longer than Noslers" - this might be your problem. If your bullet is into the rifling this will increase pressure even with a larger case capacity. Check your bullet jump and try loading them at Nosler's OAL and see what happens.

I am .075” away from the rifling. I was going to load to Nosler length, but my magazine allows me to at least get out a little further. I know for sure I am a long ways away from the rifling causing pressure issues.

[newton]

I didn't know Nosler ever gave an OAL in their reloading manuals.

I’m not sure on their book manuals, but their online data shows OAL for each bullet.

https://load-data.nosler.com/wp-cont...ersion-8-3.pdf

[newton]

With just 1 shot per incremental increase in powder charge it's hard to determine anything based on velocity other than the velocity increased as the charge increased.....but we already know that. Problem with a 1 shot test of any load is you've no idea of the ES of that load. Therefor you've no idea if the recorded 1 shots velocity was in the top end, the bottom end or the middle of the velocity ES for that load.

Basically your target is a representation of the oft misused Audette Ladder as a means of load development. Since the method is misused it really tells you nothing because you have no idea of the cone of fire (group potential) of any load. Ergo, not knowing the size of the group you've no idea where in the cone of fire that bullet went.

If you want a hunting load I suggest testing 3 five shot groups of loads 7 through 11 looking for the best accuracy. That will give you the best of both velocity and accuracy for hunting.

If you're looking for a target accuracy load then test ten shot groups of loads 4 through 7 as accuracy is the name of that game.

Back in the day IMR 4064 was a favored powder for loading 3.08W match loads with 168 MKs. The standard load was 42 gr.

I always value your input Larry. So please don’t take this the wrong way. I’ve loaded for a few cartridges now, not near as much as you I know, but I have never run into a cartridge where I could have a range of 2 full grains and not move much in velocity much.

I know that ES could be crazy high, but this just seemed way weird. Maybe it was just a fluke. I plan to do more testing, and knowing that anything past the low end looked like it was going to group well enough makes me feel good about starting there.

I just never had this happen before. I’ve shot many incremental loads like this, singularly, and have always seen some rise as I go up. Maybe not always a big, not always just small, but never hanging out in one area for a 5% increase in charge weight.

[newton]

Just to clarify, the target was only an aiming spot. Never was meant to be looking for group size. Only the last three shots in the lower corner were a little test for group. Even at that, it was not meant to be a serious test.

[244]

Your test seems much like Dan Newberry's Optimal Charge Weight (OCW) method. If you are not already familiar, perhaps reading his explanation will be useful.

http://optimalchargeweight.embarqspace.com/