Posted: 1/5/2009 12:24:40 AM EDT
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I know, wrong forum but this is a service rifle load so I put it here. Mods feel free to move it if you want..
I shoot a pretty common load of 24gr of Varget in a LC case, CCI 400 primer under a 77gr SMK seated to 2.250. It shoots well. But, I do notice that the primers are flattened and a slight cratering No flowing brass or other pressure indicators. I have read that lots of shooters get the same with the CCI 400's and I have also theorized that I might be bumping the shoulder back a little too far during sizing. The only other thing I can think of is to seat them out a bit further, maybe 2.260"? In comparison, over the weekend a buddy of mine shot my rifle in the following relay and was using 55 gr FC American Eagle that had LC headstamps and the NATO cross with no flattening of the primers at all. and on the opposite side I reloaded some rounds with 24.5gr of Varget and got cratered primers and much more flattening with that load.. I had the same with a stating load of 23.5 when I first got the upper. So what gives? I havent run the load thru a chrono yet.. As for sizing, I am running thru a batch of once fired LC so I have been FL sizing all of them which brings me to my next question. I have about 500 rounds of LC brass that I have fired tru my rifle and this was all FL sized after I decrimped and trimmed it to length. Would I run into reliability or feeding issues if I was to only bump the shoulder back a couple thousanths on this since it has been run thru my gun already? The rifle is a RRA upper with a Wylde chamber. Anyone run into this? 
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From the sounds of what you observed and looking at those cratered primers, you have got to make a change. Try seating the bullet .010" deeper into the case. If it improves then seat it another .005" - .010" and take a look. You may also back the powder down a bit after you get some improvement with the cratering from deeper seating.
Cratered primers have 2 main causes. The first is a weak firing pin spring, but this won't apply to an AR with the inertia driven pin; and it would also occur across the board with loads. The second cause is high pressure too early. This is what I think you have. Letting the bullet jump a bit further to the rifling will usually solve the problem, but sometimes you also have to back off on the powder. If you are cratering that bad in the winter, you will be piercing primers in the summer! |
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I think you're right,, about the shoulder bumped back a little too far. That load shouldn't show pressure. You also might have a large FP hole. 'Borg ETA, I would change primers tho. I'll try less shoulder set back. I have about 1500 of the CCI 400's though. I just looked at the bolt face thru a 10x loupe and the FP hole is definitley larger than the FP there is a gap around the FP when I push it thru. This bad? ETA the upper only has 597 rounds thru it. |
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Quoted:
I know, wrong forum but this is a service rifle load so I put it here. Mods feel free to move it if you want.. I shoot a pretty common load of 24gr of Varget in a LC case, CCI 400 primer under a 77gr SMK seated to 2.250. It shoots well. But, I do notice that the primers are flattened and a slight cratering No flowing brass or other pressure indicators. I have read that lots of shooters get the same with the CCI 400's and I have also theorized that I might be bumping the shoulder back a little too far during sizing. The only other thing I can think of is to seat them out a bit further, maybe 2.260"? In comparison, over the weekend a buddy of mine shot my rifle in the following relay and was using 55 gr FC American Eagle that had LC headstamps and the NATO cross with no flattening of the primers at all. and on the opposite side I reloaded some rounds with 24.5gr of Varget and got cratered primers and much more flattening with that load.. I had the same with a stating load of 23.5 when I first got the upper. So what gives? I havent run the load thru a chrono yet.. As for sizing, I am running thru a batch of once fired LC so I have been FL sizing all of them which brings me to my next question. I have about 500 rounds of LC brass that I have fired tru my rifle and this was all FL sized after I decrimped and trimmed it to length. Would I run into reliability or feeding issues if I was to only bump the shoulder back a couple thousanths on this since it has been run thru my gun already? The rifle is a RRA upper with a Wylde chamber. Anyone run into this? http://i242.photobucket.com/albums/ff110/1mccarty/FiredBrass.jpg?t=1231147250 It may have more to do with your brass, primers, or OAL than the powder charge. I am shooting the same rifle with almost the same load except for brass and primers, and I have not run into that problem. I am using R-P case set back .002, with 24.0 gr of Varget primed with a 205M primer with OAL of 2.260. They only chrono at 2,608 fps even though it is a max load as listed on Hodgon's site. I have shot with people that say with 24.5 grs of Varget they are around 2,800 fps, but you can't prove it with my experience. A fellow shooter in another thread here reported using 24.0 grs of RL-15 and is getting 2,754 fps. I can only assume since it is in this forum that it was indeed a 20" barrel similar to ours. |
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I know, wrong forum but this is a service rifle load so I put it here. Mods feel free to move it if you want.. I shoot a pretty common load of 24gr of Varget in a LC case, CCI 400 primer under a 77gr SMK seated to 2.250. It shoots well. But, I do notice that the primers are flattened and a slight cratering No flowing brass or other pressure indicators. I have read that lots of shooters get the same with the CCI 400's and I have also theorized that I might be bumping the shoulder back a little too far during sizing. The only other thing I can think of is to seat them out a bit further, maybe 2.260"? In comparison, over the weekend a buddy of mine shot my rifle in the following relay and was using 55 gr FC American Eagle that had LC headstamps and the NATO cross with no flattening of the primers at all. and on the opposite side I reloaded some rounds with 24.5gr of Varget and got cratered primers and much more flattening with that load.. I had the same with a stating load of 23.5 when I first got the upper. So what gives? I havent run the load thru a chrono yet.. As for sizing, I am running thru a batch of once fired LC so I have been FL sizing all of them which brings me to my next question. I have about 500 rounds of LC brass that I have fired tru my rifle and this was all FL sized after I decrimped and trimmed it to length. Would I run into reliability or feeding issues if I was to only bump the shoulder back a couple thousanths on this since it has been run thru my gun already? The rifle is a RRA upper with a Wylde chamber. Anyone run into this? http://i242.photobucket.com/albums/ff110/1mccarty/FiredBrass.jpg?t=1231147250 It may have more to do with your brass, primers, or OAL than the powder charge. I am shooting the same rifle with almost the same load except for brass and primers, and I have not run into that problem. I am using R-P case set back .002, with 24.0 gr of Varget primed with a 205M primer with OAL of 2.260. They only chrono at 2,608 fps even though it is a max load as listed on Hodgon's site. I have shot with people that say with 24.5 grs of Varget they are around 2,800 fps, but you can't prove it with my experience. A fellow shooter in another thread here reported using 24.0 grs of RL-15 and is getting 2,754 fps. I can only assume since it is in this forum that it was indeed a 20" barrel similar to ours. About a year and a half ago Hodgon reduced the published max load on their web site. IIRC it was 24.7grs for the 77's before the change. Maybe their powder recipe changed, I dont know? I definitely have a slightly large FP hole, I can see it easily with a loupe.. I also think Im bumping the shoulder back too far. I have to buy some new componants as Im flat out of powder and bullets so I'll have to see what happens. Instead of resizing FL I'll just bump one or two thousandths on the shoulder and see what that does.. |
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In my testing of reloads using Varget, I came to the conclusion that 24.0 gr of Varget was the maximum safe load I could use. It was the highest powder charge that still showed some margin of safety. That is, 24.5 gr was a very hot load.
This conclusion was drawn using: Winchester brass Winchester SR primers 2.250" OAL Shoulder set back 0.002" Bullets - 75 gr Hornady HPBT-M and 80 gr Sierra MatchKing What I am saying is, you got the right answer - 24.0 is a max load. |
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In my testing of reloads using Varget, I came to the conclusion that 24.0 gr of Varget was the maximum safe load I could use. It was the highest powder charge that still showed some margin of safety. That is, 24.5 gr was a very hot load. This conclusion was drawn using: Winchester brass Winchester SR primers 2.250" OAL Shoulder set back 0.002" Bullets - 75 gr Hornady HPBT-M and 80 gr Sierra MatchKing What I am saying is, you got the right answer - 24.0 is a max load. Interesting. Like I noted above they must have changed their recipe a bit. |
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I measured my FP hole and it is .061" and the FP itself is .060". I dont know if thats a big problem or norma
But I think I have found the problem. I measured a FL sized with a Hornady LnL headspace guage and found that it measured 1.455" to the shoulder where a fired case measured 1.465". Clearly I am setting the shoulder back to far. I think I am allowing the primer to unseat a bit due to the excessive HS and it is flowing into the bolt face, flattenting and cratering. Like I said, Ill try to go with a couple thousnaths max on the shoulder setback. |
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The seating depth has a lot to do with pressure and what powder charges are safe. Say for instance you have you rifle throated long (maybe for a long range Service Rifle) that you are only going to be using for Long Range matches, you will probably be able to put a little more powder in behind the bullet because you can seat the bullets out long. The case volume becomes significantly greater.
If you have a short throat (say for an Infantry Trophy gun, set up to shoot 75s at mag length), your case volume goes down in comparison. B |
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The seating depth has a lot to do with pressure and what powder charges are safe. Say for instance you have you rifle throated long (maybe for a long range Service Rifle) that you are only going to be using for Long Range matches, you will probably be able to put a little more powder in behind the bullet because you can seat the bullets out long. The case volume becomes significantly greater. If you have a short throat (say for an Infantry Trophy gun, set up to shoot 75s at mag length), your case volume goes down in comparison. B These are mag length reloads for reduced course matches and what I would shoot out to 300. I could prbably seat them out just a tad further to 2.260" but that would be it. not sure how much that would change things. I do know i have a lot of shoulder set back that I need to eliminate and that is likely a big contibutor to the issue. |
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The primers are not flattened. What I'm familiar with (as signs of high pressure) is the virtual disappearance of that radius at the outside edge of the primer where it meets the primer pocket in the brass.
Yes, the primer can crater back into the firing pin hole in the bolt face as well but if the primer is cratering due to pressure why isn't the radius around the edge flattening out as well? In the past I've seen the flattening, or reduction of the radius before cratering of the primer around the firing pin indentation. I've always read that an enlarged firing pin hole in the bolt face can promote such deformation of the primer even below maximum pressures. In any case. Go slow. The CCI military primers are supposed to have a thicker wall than the civilian primers. |
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For my 2 cents. If you have set your shoulder back too far (from SAAMI spec.) you are creating a head space problem. This will give you excessive pressure signs along with shortened brass life and probably some accuracy loss.
I would suggest purchasing a Wilson or Lyman "cartridge head space gauge". Using one of these gages eliminates all the guess work of setting up your sizing die. Available from several suppliers like Midway USA etc. I have one of these gauges for every bottleneck rifle caliber I load for. Never a problem 
Seating the bullets deeper in the case, especially with this heavy bullet will increase pressure due to less case volume and possibly compressing the powder charge. Since you have a Wylde chamber, the 77 SMK, even at 2.260" will not be bumping the rifling. This is why the Wylde chamber came about. Increasing the leade for using the heavy bullets like the 75's, 77's and 80's. The same principal Weatherby has used for many years for their line of magnum cartridges. Doing so, they were never known for their rifles accuracy but better known for their high velocity at safe pressure levels. On the Hodgdon Varget, it seems they have changed their formula at least two times, maybe more. That is why I went to RE-15 several years ago. Opening a new 8 pounder of Varget, I always had to work up or tweak my loads again. With RE15, never a issue or a problem. The CCI 400 primer while not my favorite, isn't a bad choice but I would recommend the Federal 205M or the Rem. 7 1/2 BR. Dave McGrath |
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The primers are not flattened. What I'm familiar with (as signs of high pressure) is the virtual disappearance of that radius at the outside edge of the primer where it meets the primer pocket in the brass. Yes, the primer can crater back into the firing pin hole in the bolt face as well but if the primer is cratering due to pressure why isn't the radius around the edge flattening out as well? In the past I've seen the flattening, or reduction of the radius before cratering of the primer around the firing pin indentation. I've always read that an enlarged firing pin hole in the bolt face can promote such deformation of the primer even below maximum pressures. In any case. Go slow. The CCI military primers are supposed to have a thicker wall than the civilian primers. They dont have the more radiused edge as a factory round but comparing them to unfired CCI 400 primers the radius is about the same. My FP hole is about .001" larger than the FP and I was FL sizing the brass shich set the shoulder back quite a bit. I just ran a few thru the dies and set it up to knock the shoulder back about 2-3 thousndths of an inch. I'm gonna stick with the same loading and seat the bullet a bit further out to 2.260" and see what happens. |
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For my 2 cents. If you have set your shoulder back too far (from SAAMI spec.) you are creating a head space problem. This will give you excessive pressure signs along with shortened brass life and probably some accuracy loss. I would suggest purchasing a Wilson or Lyman "cartridge head space gauge". Using one of these gages eliminates all the guess work of setting up your sizing die. Available from several suppliers like Midway USA etc. I have one of these gauges for every bottleneck rifle caliber I load for. Never a problem
Seating the bullets deeper in the case, especially with this heavy bullet will increase pressure due to less case volume and possibly compressing the powder charge. Since you have a Wylde chamber, the 77 SMK, even at 2.260" will not be bumping the rifling. This is why the Wylde chamber came about. Increasing the leade for using the heavy bullets like the 75's, 77's and 80's. The same principal Weatherby has used for many years for their line of magnum cartridges. Doing so, they were never known for their rifles accuracy but better known for their high velocity at safe pressure levels. On the Hodgdon Varget, it seems they have changed their formula at least two times, maybe more. That is why I went to RE-15 several years ago. Opening a new 8 pounder of Varget, I always had to work up or tweak my loads again. With RE15, never a issue or a problem. The CCI 400 primer while not my favorite, isn't a bad choice but I would recommend the Federal 205M or the Rem. 7 1/2 BR. Dave McGrath Dave, Looks like I was setting the shoulder back at least .010" from my max headspace. Im using the Hornady LnL gauges and a digital caliper. Im sure the FP was driving that case forawrd and then as it expanded during ignition the case stayed put and the primer backed up against the bolt face leading to what I am seeing here. In any case, I have been thinking of trying RE15, Varget is pretty dirty but it shoots good. Im all out so I need to decide. |
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I have read about some differences from lot to lot with Varget, but the only experience I had was comparing a can from about 2001 to one that I purchased this past year. I loaded up some rounds using equal amounts from each lot, and obtained pretty much the same velocity.
By looking at other shooter's results, it seems that RE-15 produces better velocity. Is it also an extruded powder, and is it cleaner than Varget? |
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For my 2 cents. If you have set your shoulder back too far (from SAAMI spec.) you are creating a head space problem. This will give you excessive pressure signs along with shortened brass life and probably some accuracy loss. I would suggest purchasing a Wilson or Lyman "cartridge head space gauge". Using one of these gages eliminates all the guess work of setting up your sizing die. Available from several suppliers like Midway USA etc. I have one of these gauges for every bottleneck rifle caliber I load for. Never a problem
Seating the bullets deeper in the case, especially with this heavy bullet will increase pressure due to less case volume and possibly compressing the powder charge. Since you have a Wylde chamber, the 77 SMK, even at 2.260" will not be bumping the rifling. This is why the Wylde chamber came about. Increasing the leade for using the heavy bullets like the 75's, 77's and 80's. The same principal Weatherby has used for many years for their line of magnum cartridges. Doing so, they were never known for their rifles accuracy but better known for their high velocity at safe pressure levels. On the Hodgdon Varget, it seems they have changed their formula at least two times, maybe more. That is why I went to RE-15 several years ago. Opening a new 8 pounder of Varget, I always had to work up or tweak my loads again. With RE15, never a issue or a problem. The CCI 400 primer while not my favorite, isn't a bad choice but I would recommend the Federal 205M or the Rem. 7 1/2 BR. Dave McGrath Dave, Looks like I was setting the shoulder back at least .010" from my max headspace. Im using the Hornady LnL gauges and a digital caliper. Im sure the FP was driving that case forawrd and then as it expanded during ignition the case stayed put and the primer backed up against the bolt face leading to what I am seeing here. In any case, I have been thinking of trying RE15, Varget is pretty dirty but it shoots good. Im all out so I need to decide. Dave's got you pointed in the right direction here. .010" is way too much setback. .003" is what I've found best to work in my Wylde chamber rifles. I measure with a Hornady LNL cartride headspace guage, comparing fired brass to resized brass. As far as Varget goes. I found that powder to be quite dirty, I call it the "Blue Goo". The "Blue Goo" would build up so much that by the end of an 80 rouond match the bolt would become sticky and hard to open. It must react with the chems I use to clean my rifles as not everyone has the same problem. I switched to RE-15 early last season and have not looked back. Hope this helps... Dan |