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Posted: 7/16/2019 6:01:02 PM EDT
at my last trip to the range, I noticed my reloads were getting flattened primers. Then I noticed later even the factory IMI brass even had flat primers. I'm using 44gr of varget with a 165gr SST. The IMI was 150gr. Thats the only two types I have tried this yr, my last trip last year I shot some factory FGMM 168gr but I don't have that brass to check them.
I've read that may be from the chamber headspace. Is that a problem? Should I have the headspace checked? I'm going to shot with a chrono next time at the range so I'll get an idea of the fps my reloads are getting with the 44gr. |
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Posted: 7/16/2019 9:00:31 PM EDT
[#1]
Several things to check...is the chamber clean, no signs of a carbon ring in the chamber or throat? Pics of the brass would go a long way in seeing the issue, especially on factory ammo...
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Posted: 7/18/2019 9:05:29 PM EDT
[#2]
IMI brass is GI spec. 2.0 grain reduction in charge weights is the standard rule of thumb.
Try 42.0 grains (or less) of Varget with 165/168 grain bullets. |
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IA, USA
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Posted: 7/20/2019 3:24:26 AM EDT
[#3]
Typical AR10 platform. Get an adjustable gas block and tune it down.
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Posted: 7/20/2019 10:48:31 AM EDT
[#4]
Quote HistoryOriginally Posted By borderpatrol:
IMI brass is GI spec. 2.0 grain reduction in charge weights is the standard rule of thumb. Try 42.0 grains (or less) of Varget with 165/168 grain bullets. |
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Posted: 7/20/2019 10:49:29 AM EDT
[#5]
Quote HistoryOriginally Posted By tommee-boy-72:
Typical AR10 platform. Get an adjustable gas block and tune it down. |
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Posted: 7/20/2019 6:56:43 PM EDT
[#6]
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Posted: 7/20/2019 6:59:46 PM EDT
[#7]
pics of the cases don't do it justice, but you can see on the federal primers a little material smeared up past the firing pin recess.
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IA, USA
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Posted: 7/20/2019 9:09:48 PM EDT
[#8]
Cut off the gas. The bolt is unlocking too soon. Shut it down till it will not cycle. Then open it till it does then leave it there. These ar10's are HARD on brass.
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Posted: 7/20/2019 10:45:41 PM EDT
[#9]
Gas was cut back till the bolt wouldn't lock back. I still had trouble today with it not locking back.
It ran fine before i changed the stock so i don't get it. It has a 5.6oz buffer in it swapped from the og H buffer. I figured, one shot, and open it till the bolt locked back, and 1/4 turn more and lock it down.... wtf |
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Posted: 7/20/2019 11:23:24 PM EDT
[Last Edit: snakeyes711]
[#10]
Also, kept getting a ftf occasionally. Sro said he thought the bolt was too fast for the magg from to much pressure, But when i did the bolt wouldn't lock back.
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Posted: 7/22/2019 12:11:40 AM EDT
[#11]
The IMI factory is "full power". The Federal reloads are something more than that.
Drop your powder charge and I bet your problem disappears. Try 41.5, 42.0 and 42.5 grains of Varget and see which one groups the best. |
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Posted: 7/22/2019 12:15:15 AM EDT
[#12]
BTW - Hornady's manual lists 42.7 grains of Varget as a maximum load for semi-auto rifles.
2600 fps from a 22" barrel, that's around 2550 fps from a 20", 2500 from an 18". |
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Posted: 7/22/2019 11:59:20 AM EDT
[Last Edit: snakeyes711]
[#13]
Quote HistoryOriginally Posted By borderpatrol:
BTW - Hornady's manual lists 42.7 grains of Varget as a maximum load for semi-auto rifles. 2600 fps from a 22" barrel, that's around 2550 fps from a 20", 2500 from an 18". 
These are 44gr... |
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Posted: 7/22/2019 12:00:47 PM EDT
[#14]
Quote HistoryOriginally Posted By borderpatrol:
The IMI factory is "full power". The Federal reloads are something more than that. Drop your powder charge and I bet your problem disappears. Try 41.5, 42.0 and 42.5 grains of Varget and see which one groups the best. |
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Posted: 7/22/2019 12:11:01 PM EDT
[Last Edit: wildearp]
[#15]
My PA10 did that. They are overgassed. You need an adjustable gas block. Another choice is a Criterion barrel, no adj. gas block needed.
I also had severe ejector marks and blown primers. My rounds were completely safe when re-weighed and chrono graphed. 6 clicks from closed. 
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Posted: 7/22/2019 12:14:50 PM EDT
[Last Edit: wildearp]
[#16]
Quote HistoryOriginally Posted By snakeyes711:
https://live.staticflickr.com/65535/48333225122_19526c14e1_k.jpg20190720_185133 by Teresa King, on Flickr" target="_blank">https://live.staticflickr.com/65535/48333225122_19526c14e1_k.jpg20190720_185133 by Teresa King, on Flickr https://live.staticflickr.com/65535/48333090206_c47cbff1b0_k.jpg20190720_185129 by Teresa King, on Flickr" target="_blank">https://live.staticflickr.com/65535/48333090206_c47cbff1b0_k.jpg20190720_185129 by Teresa King, on Flickr I also bought a Magnetospeed just to diagnose this issue. My rounds were completely safe. When I was over gassed, I had severe ejector marks and even some bent rims (caused by the extractor) on the cases, along with blown primers. I tried the gas block first and it solved the gas issues, and then eventually found out my barrel just would not group, which is why I picked the Criterion. I also changed from the mid length gas to rifle length gas. What barrel length and gas length do you have? |
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Posted: 7/22/2019 2:10:35 PM EDT
[Last Edit: snakeyes711]
[#17]
Quote HistoryOriginally Posted By wildearp:
My PA10 did that. They are overgassed. You need an adjustable gas block. Another choice is a Criterion barrel, no adj. gas block needed. I also had severe ejector marks and blown primers. My rounds were completely safe when re-weighed and chrono graphed. 6 clicks from closed. https://i.imgur.com/ZWFxBiP.jpg Mid length 18" |
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Posted: 7/22/2019 9:39:14 PM EDT
[#18]
Quote HistoryOriginally Posted By snakeyes711:
I've shot those except 41.5 |
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Posted: 7/23/2019 9:44:37 AM EDT
[Last Edit: snakeyes711]
[#19]
Quote HistoryOriginally Posted By borderpatrol: What were the results? Accurate? Reliable? Better looking primers? |
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Posted: 7/23/2019 10:31:42 AM EDT
[#20]
This is pretty common in the large frame gas guns. I see brass on ranges all the time shot of out of gas guns that looks horrible, 6.5mms seem to be even worse with near case head separations being not entirely uncommon.
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Posted: 7/23/2019 10:31:54 AM EDT
[Last Edit: TeeRex]
[#21]
DT.
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Posted: 8/3/2019 10:13:56 PM EDT
[#22]
Quote HistoryOriginally Posted By snakeyes711: It was factory imi loads And while those IMI primers look flattened... I have seen far worse. What primer are you using in your reloads ? Some primer cups are softer then others ... and how easily do the primers push out ? I also don't see typical other signs of troublesome over pressure... ejector flow and the smear from that, or the typical excess extractor damage on the case rim associated with trying to yank the case out under extreme pressures...( slightly bent rims disfigured rims ) Hodgdon Reloading data has 2 separate 308 Winc. load recipes for 308. 308 Winc. ... and 308 Winc. Service Rifle. ( gas operated ) The Hogdon 308 Winc. Service Rifle load data is lower pressure, and also more oriented towards proper gas port pressures found in S/A rifles. Especially M1A's and M1's Even that has a max of 43.2gr w/ a 168gr bullet The Hodgdon 308 Winc. load data is more oriented to bolt guns. And that charge weight is much higher. Where did you get your load data from ? I would back off your Varget charge weight. Since your chamber / barrel doesn't like it. |
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Posted: 8/4/2019 12:03:44 AM EDT
[Last Edit: snakeyes711]
[#23]
Quote HistoryOriginally Posted By bfoosh06: All IMI factory ammo has been known to be loaded hot, on and off over the years. Your 308 may be one of those hotter loads. And while those IMI primers look flattened... I have seen far worse. What primer are you using in your reloads ? Some primer cups are softer then others ... and how easily do the primers push out ? I also don't see typical other signs of troublesome over pressure... ejector flow and the smear from that, or the typical excess extractor damage on the case rim associated with trying to yank the case out under extreme pressures...( slightly bent rims disfigured rims ) Hodgdon Reloading data has 2 separate 308 Winc. load recipes for 308. 308 Winc. ... and 308 Winc. Service Rifle. ( gas operated ) The Hogdon 308 Winc. Service Rifle load data is lower pressure, and also more oriented towards proper gas port pressures found in S/A rifles. Especially M1A's and M1's Even that has a max of 43.2gr w/ a 168gr bullet The Hodgdon 308 Winc. load data is more oriented to bolt guns. And that charge weight is much higher. Where did you get your load data from ? I would back off your Varget charge weight. Since your chamber / barrel doesn't like it. |
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