I’ve been loading and shooting .308 for many years. For much of that I used 4064 behind a 165 gr Hornady btsp. Then a few years ago I picked up an Armalite AR-10T and worked up a load with LC brass, 168 gr Hornady A-Max, 42.5 grains of Varget with CCI 250 Large Rifle Magnum primers. The Lake City loads of 42.5 grs of Varget behind a 168 gr Amax were around 2550 FPS. About a month ago I picked up a FNAR and discovered that it didn’t like Lake City Brass. I did find out that the FNAR grouped much better so far using Federal Brass. So today while working up loads I was running my stash of older proven loads for the AR-10T and decided to load them a bit hotter than the 42.5 gr Varget load. My son-in-law and I were in the front yard shooting at my 100 yard range and I had loaded up 5 rounds of 43.5 grains Varget, CCI 250 behind a 168 A-Max Hornady bullet. So we are setting in the front yard and using the Chronograph the first 5 rounds of the 43.5 gr load and to our surprise the Chronograph was showing an average of 3686 FPS with an extreme spread of 43.68 and standard deviation of 21.11. Now I know this is impossible and the brass didn’t show any signs of too much pressure and the rifle didn’t feel wrong. After that 5 rounds I fired 5 of my old 42.5 gr load and the chronograph showed 2550 FPS with a lousy group. I went back inside and loaded 5 more 43.5 gr loads and this time the chronograph showed 5485 average and the 42,5 gr load still was around 2500 FPS. I changed the chronograph battery and the velocity went to 2695 for an Average . This was a first for me. I’ve got what I thought was the one of the best chronograph. Any idea’s on why the new load showed so fast but the old load was normal? This spooked me as I’ve been reloading for over 30 years and chronographing loads since I first picked up my Olher 33. Right now I’m using a Chrony Gama model with the printer. I’ve got a lot of work to do in working up the load that is best for FNAR and I’m looking forward to getting this right. Anyone ever run into this type of problem.
-
Having trouble using the site?
Contact support
Strange problem while loading .308
- Thread starter ridurall
- Start date
Re: Strange problem while loading .308
Greetings, Ron. Got the bottle openers in good shape. Thanks! I had problems with the Chrony. Shadows, lights, glints, inconsistencies...you name it. Once I found that the folding hinge had stuck so the screens were minutely closer together. That made the loads a hundred or more fps faster. Not the 1000. I suspect internal glitches in the motherboard coupled with some external impulses. I don't have the Chrony anymore. Go back to your Oehler. Good luck.
Greetings, Ron. Got the bottle openers in good shape. Thanks! I had problems with the Chrony. Shadows, lights, glints, inconsistencies...you name it. Once I found that the folding hinge had stuck so the screens were minutely closer together. That made the loads a hundred or more fps faster. Not the 1000. I suspect internal glitches in the motherboard coupled with some external impulses. I don't have the Chrony anymore. Go back to your Oehler. Good luck.
Re: Strange problem while loading .308
Low power (electrical,battery) can cause just that sort of problem. Don't understand why you had normal readings for your standard load though. Or being close enough for muzzle blast to affect chrony. I'm usually at around 12 ft. from the muzzle.
Low power (electrical,battery) can cause just that sort of problem. Don't understand why you had normal readings for your standard load though. Or being close enough for muzzle blast to affect chrony. I'm usually at around 12 ft. from the muzzle.
Re: Strange problem while loading .308
I always set my chrony up as far away as I can. Being that I have a CED M2, that means the full length of the cables, which is about 20ft. I've definitely experienced all sorts of issues with Chronys.... I kinda hate them.
In your case, is it possible the muzzle blast of your 42.5 load wasn't enough to screw up the reading, but 43.5 was?
Also, in your post you mention 2550fps for 42.5, then 2500fps for 42.5... Then you said after the battery change you got ~2700fps from 43.5?
That is 150-200fps from one grain more powder??????? Seems off to me. I'd expect more like 100fps, but you never know.
I always set my chrony up as far away as I can. Being that I have a CED M2, that means the full length of the cables, which is about 20ft. I've definitely experienced all sorts of issues with Chronys.... I kinda hate them.
In your case, is it possible the muzzle blast of your 42.5 load wasn't enough to screw up the reading, but 43.5 was?
Also, in your post you mention 2550fps for 42.5, then 2500fps for 42.5... Then you said after the battery change you got ~2700fps from 43.5?
That is 150-200fps from one grain more powder??????? Seems off to me. I'd expect more like 100fps, but you never know.
Re: Strange problem while loading .308
The actual velocity for the 42.5 load was 2550 FPS and I just rounded down when I mentioned the 2500 FPS. I had not thought about the hinge that could be a problem, I'll have to remember that. I do suppose I could have moved it a bit farther away. Usually I set it as far away as the printer cord will allow and don't even have a problem chronographing the 50 BMG. This time is was closer so you might have something there. I've got a lot more loads to test so thank you for the food for thought.
Thanks guys.
The actual velocity for the 42.5 load was 2550 FPS and I just rounded down when I mentioned the 2500 FPS. I had not thought about the hinge that could be a problem, I'll have to remember that. I do suppose I could have moved it a bit farther away. Usually I set it as far away as the printer cord will allow and don't even have a problem chronographing the 50 BMG. This time is was closer so you might have something there. I've got a lot more loads to test so thank you for the food for thought.
Thanks guys.
Re: Strange problem while loading .308
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: former naval person</div><div class="ubbcode-body">[snip]
Once I found that the folding hinge had stuck so the screens were minutely closer together. That made the loads a hundred or more fps faster. [snip]
</div></div>
Let's see, if the Chrony you speak of had 18 inches of screen spacing unfolded (I'm not familiar with that), the hinge would have to be so the "sensor area" of the screens' image of the bullet path fully .705 inch closer together for a 2550 fps load. (Less for shorter screen distance, more for more.) My rough understanding of geometry puts that as being a pretty big deviation from fully unfolded.
It's just a math thing.
Screens 10% closer than they're supposed to be will read 10% faster, 10% farther will read 9.sumthin' percent slower.
Unless I got it backwards.
To the OP, I can report some hugely high speeds from a lowly .357 Magnum under conditions where either the gas cloud's shadow, or the shock wave's shadow (at speed of sound it couldn't have reached it sooner), triggered the stop screen long before the bullet got there.
*****
Two different powders, possibly slightly higher or lower bullet paths affecting the possible shadow factor.
So, I really don't know a thing about YOUR situation but I think I can guess real good!
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: former naval person</div><div class="ubbcode-body">[snip]
Once I found that the folding hinge had stuck so the screens were minutely closer together. That made the loads a hundred or more fps faster. [snip]
</div></div>
Let's see, if the Chrony you speak of had 18 inches of screen spacing unfolded (I'm not familiar with that), the hinge would have to be so the "sensor area" of the screens' image of the bullet path fully .705 inch closer together for a 2550 fps load. (Less for shorter screen distance, more for more.) My rough understanding of geometry puts that as being a pretty big deviation from fully unfolded.
It's just a math thing.
Screens 10% closer than they're supposed to be will read 10% faster, 10% farther will read 9.sumthin' percent slower.
Unless I got it backwards.
To the OP, I can report some hugely high speeds from a lowly .357 Magnum under conditions where either the gas cloud's shadow, or the shock wave's shadow (at speed of sound it couldn't have reached it sooner), triggered the stop screen long before the bullet got there.
*****
Two different powders, possibly slightly higher or lower bullet paths affecting the possible shadow factor.
So, I really don't know a thing about YOUR situation but I think I can guess real good!
Re: Strange problem while loading .308
I guess the biggest deal was when I saw 5500 FPS on my Chronograph and even knowing that was impossible I still had to check the brass for cratering or other signs of high pressure. When there were none I knew it had to be something different.
From now on, I'm moving the chronograph as far away as the printer will allow. You all have given me some wonderful things to think about and correct. I want to wring the best accuracy that I can out of this FNAR and of course my AR-10T.
Ron
I guess the biggest deal was when I saw 5500 FPS on my Chronograph and even knowing that was impossible I still had to check the brass for cratering or other signs of high pressure. When there were none I knew it had to be something different.
From now on, I'm moving the chronograph as far away as the printer will allow. You all have given me some wonderful things to think about and correct. I want to wring the best accuracy that I can out of this FNAR and of course my AR-10T.
Ron
Re: Strange problem while loading .308
Sam and I got back out in the heat today at 105 % with the FNAR and my AR-10T. We tried 43.7 gr of Varget for a velocity average of 2645 out of the FNAR and a 2 ½ inch group. The Extreme spread was 107 FPS. Not good at all. Oh I set the Chronograph as far away as the printer cord would allow. I didn’t have any of the variable velocity problems that I had yesterday.
I then bumped the load up to 44 grs of Varget for an average of 2717 and 1 ¼ inch groups. Much better but I do hope to bring the groups down more. When I went back to the 43.5 gr load that I had so much trouble with before the groups were not any better than the 43.7 charge I got an average velocity of 2673 and extreme spread of 225 FPS. Sucks! I then decided to try the 44 gr load in my AR-10T with 24” barrel. Average velocity of 2817 ES 90.36 and ¾ groups. I was impressed with it. I’ve got more work to do but at least I got the bugs worked out of the Chronograph. I just think I was too close to it.
Thanks for all your help. I tell you it’s hard to beat the Armalite AR-10T.
Sam and I got back out in the heat today at 105 % with the FNAR and my AR-10T. We tried 43.7 gr of Varget for a velocity average of 2645 out of the FNAR and a 2 ½ inch group. The Extreme spread was 107 FPS. Not good at all. Oh I set the Chronograph as far away as the printer cord would allow. I didn’t have any of the variable velocity problems that I had yesterday.
I then bumped the load up to 44 grs of Varget for an average of 2717 and 1 ¼ inch groups. Much better but I do hope to bring the groups down more. When I went back to the 43.5 gr load that I had so much trouble with before the groups were not any better than the 43.7 charge I got an average velocity of 2673 and extreme spread of 225 FPS. Sucks! I then decided to try the 44 gr load in my AR-10T with 24” barrel. Average velocity of 2817 ES 90.36 and ¾ groups. I was impressed with it. I’ve got more work to do but at least I got the bugs worked out of the Chronograph. I just think I was too close to it.
Thanks for all your help. I tell you it’s hard to beat the Armalite AR-10T.
Re: Strange problem while loading .308
Ron...I'd suggest a few things...which you may or may not be doing. Brass prep...polishing the insides of the necks. Neck tension. What variance of thickness of the neck are you experiencing? Primer flash hole inside reaming? Dry lube the inside of the necks before seating the bullets. Try for .003 or .004 for the tension since it is a semi. Further...Try different primers. The CCI Mags do well in that persuasion, although I prefer the Fed 210 and the Wolf LR's. Primers can make a significant difference in the velocity variation...Then, consider a different powder. 4895 is the old standard, as is 4064. The change in the brass can be significant also. My rifles like the 42.5 Varget in the Federal brass. With Wolf primers. OAL in my rifles is more than 2.800. That may help, but magazine length may limit you. You should be able to better the extreme spread. Good luck. FNP
Ron...I'd suggest a few things...which you may or may not be doing. Brass prep...polishing the insides of the necks. Neck tension. What variance of thickness of the neck are you experiencing? Primer flash hole inside reaming? Dry lube the inside of the necks before seating the bullets. Try for .003 or .004 for the tension since it is a semi. Further...Try different primers. The CCI Mags do well in that persuasion, although I prefer the Fed 210 and the Wolf LR's. Primers can make a significant difference in the velocity variation...Then, consider a different powder. 4895 is the old standard, as is 4064. The change in the brass can be significant also. My rifles like the 42.5 Varget in the Federal brass. With Wolf primers. OAL in my rifles is more than 2.800. That may help, but magazine length may limit you. You should be able to better the extreme spread. Good luck. FNP
Re: Strange problem while loading .308
That is one place where I got lazy by not using my lube powder inside the case neck. I usually do that. I've played with almost every brand of brass and I was pleasantly surprised at the Federal Brass for accuracy. Every case was trimmed with a Lee trimmer and deburred inside and outside. I've got a Forester Neck reamer but I use that more often on the 50 BMG. I will get with the program on the neck lube. I don't know why I didn't bother with that this time. I do want to get that SD down much lower.
That is one place where I got lazy by not using my lube powder inside the case neck. I usually do that. I've played with almost every brand of brass and I was pleasantly surprised at the Federal Brass for accuracy. Every case was trimmed with a Lee trimmer and deburred inside and outside. I've got a Forester Neck reamer but I use that more often on the 50 BMG. I will get with the program on the neck lube. I don't know why I didn't bother with that this time. I do want to get that SD down much lower.
Re: Strange problem while loading .308
Paul, I forgot to add that I do clean out the primer pocket and flash hole. As for switching primers, I've got a few thousand CCI 250 Large Magnum Rifle and it was a consolidation so I didn't have so many different types of primers. When I first started loading .308 for my model 70 Winchester Featherweight I used 4064 and could consistantly shoot under 1/2 MOA. When I got that rifle I got lucky to find a factory light weight barreled gun with that kind of accuracy. I'm sending my wife on a Montana Elk/Mule Deer hunt in November with it and since she has to use factory ammo she will be using Hornady Superformance 165 gr. That rifle has always liked that weight bullet. It's one gun that I wouldn't take $2000 for. Even though I purchased it in 1983 for no where near that amount.
Paul, I forgot to add that I do clean out the primer pocket and flash hole. As for switching primers, I've got a few thousand CCI 250 Large Magnum Rifle and it was a consolidation so I didn't have so many different types of primers. When I first started loading .308 for my model 70 Winchester Featherweight I used 4064 and could consistantly shoot under 1/2 MOA. When I got that rifle I got lucky to find a factory light weight barreled gun with that kind of accuracy. I'm sending my wife on a Montana Elk/Mule Deer hunt in November with it and since she has to use factory ammo she will be using Hornady Superformance 165 gr. That rifle has always liked that weight bullet. It's one gun that I wouldn't take $2000 for. Even though I purchased it in 1983 for no where near that amount.
Re: Strange problem while loading .308
Is there a possibility that the light was somehow coming in from a different angle during that strange velocity group?
I sometimes have weird velocities show up at random, especially when people with brakes are shooting near me.
Is there a possibility that the light was somehow coming in from a different angle during that strange velocity group?
I sometimes have weird velocities show up at random, especially when people with brakes are shooting near me.
Re: Strange problem while loading .308
I did have the defusers mounted on the top of it to block stray light. My bet is that it was closer then I usually use it and with new batteries and being farther away it seemed to solve the problem.
I did have the defusers mounted on the top of it to block stray light. My bet is that it was closer then I usually use it and with new batteries and being farther away it seemed to solve the problem.
Re: Strange problem while loading .308
Did some more loading today and took some advice from Paul. While using the Lee case trimmer that kind of polishes the mouth of the case, I also used some Midway Mica Dry White Lubricant in the case neck. Still the same 44 gr of Varget, 168 gr Amax, CCI 250 primer and Federal Cases. I was pleasantly surprised when shooting the AR-10T and got an AV Velocity of 2830 from the 24” barrel, ES of 25.8 and SD of 11.78. Much better then yesterday. I got a 4 shot group of ½ MOA with a flier on the 5th round stretching the group to 1 inch. I don’t know what caused that In the 20” FNAR .308 the same load went down to an AV of 2709, ES 35.64 & SD of 15.23. The group was 1.5 inches so I’m going to have to work on that. It was also 105 degrees today. I don’t like shooting when it’s that hot but life goes on. At least the Varget is stable at those temperatures. I did have one problem with the chronograph. It was about 6 pm and I think the way the sunlight was shining into the sky screens and I got 2 ERROR codes with the first 2 shots. The sunlight was shinning at an angle past the diffusers. We went to supper and when we came back out the sun was at a better angle and the chronograph worked perfectly.
Ron
I'll cling to my God and my guns, and you can keep the "Change".
Did some more loading today and took some advice from Paul. While using the Lee case trimmer that kind of polishes the mouth of the case, I also used some Midway Mica Dry White Lubricant in the case neck. Still the same 44 gr of Varget, 168 gr Amax, CCI 250 primer and Federal Cases. I was pleasantly surprised when shooting the AR-10T and got an AV Velocity of 2830 from the 24” barrel, ES of 25.8 and SD of 11.78. Much better then yesterday. I got a 4 shot group of ½ MOA with a flier on the 5th round stretching the group to 1 inch. I don’t know what caused that In the 20” FNAR .308 the same load went down to an AV of 2709, ES 35.64 & SD of 15.23. The group was 1.5 inches so I’m going to have to work on that. It was also 105 degrees today. I don’t like shooting when it’s that hot but life goes on. At least the Varget is stable at those temperatures. I did have one problem with the chronograph. It was about 6 pm and I think the way the sunlight was shining into the sky screens and I got 2 ERROR codes with the first 2 shots. The sunlight was shinning at an angle past the diffusers. We went to supper and when we came back out the sun was at a better angle and the chronograph worked perfectly.
Ron
I'll cling to my God and my guns, and you can keep the "Change".
Re: Strange problem while loading .308
So I am new to reloading and I have a question about varget. I just tried using it for my 18" 308 and had one of those rcbs powder dispensers. It work well with 4060 but the varget gave me super inconsistent powder dumps. I was thinking that it may be the shape of the powder.... any ideas
So I am new to reloading and I have a question about varget. I just tried using it for my 18" 308 and had one of those rcbs powder dispensers. It work well with 4060 but the varget gave me super inconsistent powder dumps. I was thinking that it may be the shape of the powder.... any ideas
