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Posted: 3/18/2016 12:38:23 AM EDT
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So I have been struggling to pin down some issues with my rifle and thought I could use the hive to help figure it out
PSA upper/Lower, CMG Trigger with a 24" Black Hole Weaponry 1/11 twist. I'm using a PA 4-14 FFP Scope 
The Load LC 13, wet tumbled, swaged and trimmed to 2.005 Winchester Large Rifle Primers 43.6grs Varget 175gr Nosler Custom Comp with a light crimp I did a ladder test from 42.5 to 45 grains. I have nothing consistent at all. Other than at 43.6(see below), I was shooting 3-5 MOA Here are the results. Best Group I could achieve at 43.6gr of Varget. I always have a flyer, no matter what. 
Another example. Both are the same load at 43.6, same POA, 
7 round shot group @ 43.6 
Brass 42.5gr Varget 
43.3gr Varget. I had a blown primer. 
I chroned the round and what I got was extremely high 43.6gr - around 2750 M80 Ball (147gr)- 2810 (for reference) So from what I can conclude here are the likely issues 1. Scope will not hold zero( Doubtful, since I can't getanything consistent with another scope) 2. Headspace Issue? 3. Short Throat, causing the pressure issue. I am thinking about returning the barrel as I can't get anything remotely accurate with this gun. |
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Quoted:
I think you are putting too much powder in them cases, its not a bolt action. Agreed. Nosler lists 43.5gr of Varget as max with a Nosler case. They list 2589fps out of a 24 inch barrel. http://www.nosler.com/nosler-load-data/308-winchester/ The "rule of thumb" when using Military cases like the LC, ius to drop the charge down a grain or two. Following this rule, your load is well above MAX. Your Velocities and your fired brass confirm this. Drop that charge down before you damage that rifle, yourself or both. |
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My M118LR clone load is 42.5gr Varget and it's not a weak/mild load. Your min/max loads must be for Winchester brass.
LC Match brass 175SMK or 178AMAX (seem interchangeable) Varget 42.5 CCI 200 2.775 LFCD about 2600fps from 23.6" Steyr HB Many others use this same load or nearly identical loads. |
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Consult muliple sources for load data...but my lyman manual is showing 45.2 gr of Varget as the max load for 175 gr hpbt and 44gr for 178 gr Amax...
So I would say you are in the safe realm. Quoted:
Agreed. Nosler lists 43.5gr of Varget as max with a Nosler case. They list 2589fps out of a 24 inch barrel. http://www.nosler.com/nosler-load-data/308-winchester/ The "rule of thumb" when using Military cases like the LC, ius to drop the charge down a grain or two. Following this rule, your load is well above MAX. Your Velocities and your fired brass confirm this. Drop that charge down before you damage that rifle, yourself or both. Quoted:
Quoted:
I think you are putting too much powder in them cases, its not a bolt action. Agreed. Nosler lists 43.5gr of Varget as max with a Nosler case. They list 2589fps out of a 24 inch barrel. http://www.nosler.com/nosler-load-data/308-winchester/ The "rule of thumb" when using Military cases like the LC, ius to drop the charge down a grain or two. Following this rule, your load is well above MAX. Your Velocities and your fired brass confirm this. Drop that charge down before you damage that rifle, yourself or both. |
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Well before jumping to conclusions and blaming the loads, I would check your setup with known good ammo. Black Hills or Fed GM match. If it can't shoot that well then you have a gun or scope problem. If it shoots fine with factory, it's your load or technique. I agree with you, I would not be happy with those targets.
Good luck and let us know what you try and how it goes. |
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Quoted:
Consult muliple sources for load data...but my lyman manual is showing 45.2 gr of Varget as the max load for 175 gr hpbt and 44gr for 178 gr Amax... So I would say you are in the safe realm. Quoted:
Consult muliple sources for load data...but my lyman manual is showing 45.2 gr of Varget as the max load for 175 gr hpbt and 44gr for 178 gr Amax... So I would say you are in the safe realm. Quoted:
Quoted:
I think you are putting too much powder in them cases, its not a bolt action. Agreed. Nosler lists 43.5gr of Varget as max with a Nosler case. They list 2589fps out of a 24 inch barrel. http://www.nosler.com/nosler-load-data/308-winchester/ The "rule of thumb" when using Military cases like the LC, ius to drop the charge down a grain or two. Following this rule, your load is well above MAX. Your Velocities and your fired brass confirm this. Drop that charge down before you damage that rifle, yourself or both. Save realm? He is well over tested velocity, Not safe realm. He is blowing Primers, not safe realm. He is using Military brass whereas published load data is using Civilian, Not safe Realm. Nosler bullet, Nosler data, 43.5gr Max with civi brass, Not in Safe realm. Nothing about his load is within the Safe realm, nothing. |
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Get rid of the crimp, it adds a level of inconsistency to match ammo and will damage the bullet's jacket by deforming it.
Lower your powder charge to 40.5 grains to 42.5 grains maximum when loading 175 grain SMK's in Lake City brass. Try a softer flamed primer, Remington 9.5 or Russian large rifle primers. .308 AR's need 55 lbs. minimum to close to 70 lbs. of torque on the barrel nut. Go higher if you need to for alignment. I bed the barrel in the upper using high temperature Loctite and allow it to set up for several days before shooting a new rifle. 35 lbs. won't cut it. Your powder charges are hot for Winchester brass in a bolt action. Based on your 24" velocities I think you are 3.0 whole grains OVER maximum with your powder charge. |
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Welcome aboard to the forum!
There is one thing that jumped out at me immediately, and this is the 3rd time in the week I have seen someone complaining about terrible accuracy. Aside from your primer-blowing loads, with cratering so prominent there is no firing pin dimple even in some of your brass, I'll tell you exactly what is contributing to your accuracy problems. The Primary Arms scope, made in China, that can't take the abuse of a rifle, especially the AR10 action, or pretty much any self-loader. The backlash they suffer from, as well as erector tube gear slipping is common, just like with other cheap Chinese optics with no real QC, terrible engineering, and shoddy construction. For those of us who have been involved in regular firearms training covering decades, we see this as the standard for Chinese and Russian optics. Sometimes they come broken out of the wrapper. Return the scope, and mount either a Vortex or NightForce scope. They are the only two manufacturers that do one specific process when mounting their retaining rings for the lenses that others don't, and that is what you need on the large frame AR's to prevent beating them to death. Next, as others have mentioned, you really need to work up a load, looking over the chronograph as you increase your charge weight increments. With .308 and similar case capacities, which is about a 40 grain usable case +/-, using the 1% rule, I load in .4 gr increments when doing my initial ladders. With the gun bagged very well, settled, with the Natural Point of Aim in the center of the target for each shot, do a ladder test with a load sequence over a chronograph, with several solid sources of reloading data for reference, taking the cases they used into mind so you have an idea about volume. |
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Can you post larger pics of the spent brass and primers ? Looks like cratered primers, and ejector marks, both signs of high pressure. yikes My dad used to say - " you're better off with a $100 rifle, and $1000 scope, than a $1000 rifle and a $100 scope " I don't mean to pile it on, but like others have said, reduce that load and get a quality scope and mount. . |
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Quoted: I would not have fired a second shot after looking at the case from the first. Should this Forum have a sticky thread showing what to look for as signs of high pressure when testing reloads? It's called the Useful Posts tacked thread. 1) Any poster can post a link to a post or thread. 2) IM me so I can set the archive toggle so posters link won't die. (be sure to send me a hot link to said thread or post). How to post a link to a post? Open post you want to link. Below the post count is a "Link to this post". Click on it and the Url will now have some numbers on the end. Copy Url, paste your link where you want. Example, http://www.ar15.com/forums/t_6_42/460320_AR_10_Serious_Accuracy_Issues.html&page=1#i4537072 Motor1's post I quoted. Notice the numbers on the end of the Url. |
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That sounds like an amazingly hot load for an AR-10/SR-25 type rifle. Those are bolt rifle loads.
I typically see pressure signs at around the halfway mark with listed .308 pressure loads. My most accurate load is 43 grains of IMR4064 with a 155gr. OTM and get very similar velocity to M80 ball out of a 16" barrel. Like others have said dial your loads WAY back and try some known factory ammunition. If it won't shoot well, look into a different scope. |
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Quoted:
Consult muliple sources for load data...but my lyman manual is showing 45.2 gr of Varget as the max load for 175 gr hpbt and 44gr for 178 gr Amax... So I would say you are in the safe realm. Quoted:
Consult muliple sources for load data...but my lyman manual is showing 45.2 gr of Varget as the max load for 175 gr hpbt and 44gr for 178 gr Amax... So I would say you are in the safe realm. Quoted:
Quoted:
I think you are putting too much powder in them cases, its not a bolt action. Agreed. Nosler lists 43.5gr of Varget as max with a Nosler case. They list 2589fps out of a 24 inch barrel. http://www.nosler.com/nosler-load-data/308-winchester/ The "rule of thumb" when using Military cases like the LC, ius to drop the charge down a grain or two. Following this rule, your load is well above MAX. Your Velocities and your fired brass confirm this. Drop that charge down before you damage that rifle, yourself or both. No.... That's WAY too hot for a .308 AR with military brass. |
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As others have stated, that load is going to do some serious damage to your brass and all functioning parts of your rifle, or face.
Work-up another load from tested reloading books or the reloading forum. Second, nothing wrong with your scope. The PA scope is a solid choice, unless it's the ACSS reticle. Those are more suited for "combat" applications or quick shots. Not so suited for precision. |
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Look at the primer extrusion into the firing pin hole. The pressure is too high, at least for that bolt. Primers are also flowing over the edge break of the primer pocket; at minimum that is a sign the load is knocking on the door of excess pressure.
Get a micrometer to measure the case head expansion compared to a new case, or at least one from the same batch that has not been fired. If the expansion is measurable, then the load is too hot. If it is more than about a half thousandth, then it's definitely too hot. Quoted:
OP registered over a year ago, this was the first and only post. We'll give him a week or two to comment, then consider locking the thread. |
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Well, I am back. A couple things I want to address,. Yes I have been registered for a long while, yet I don't ever post. I usually have no reason to. I am slowly dipping my feet into the long range field and this is the first time I have been seriously concerned with accuracy. Next, I understand that a PA scope isn't exactly top quality. I tested that scope out on another rifle and still had tracking issues so I returned it and got a new one. I will post some more pictures that I shot with this new scope. I bought a SWFA 3-15 FFP that should be here in May, so I will try everything again with that scope( if this is not good enough,,, well I can't help you).
I should've listened to my gut with that blown primer. I tend to look at load data that is using both civilian brass and in use for bolt actions. I was dumb and in this world of controlled micro explosions, I'm lucky nothing bad happened. So that being said, I revisited the issue and here is the next set of data. Same rifle, other than the scope. I loaded 175 Nosler CC with Varget ranging from 40.5-42.0 and RL15 from 40.0-42.0 gr in 1/2 grain increments. I started by zeroing the rifle in with perfecta 147gr ball ammo from walmart. You can see the extractor marks in this photo 
Here is a primer that has popped out about 1/2 way 
41.0 RL15 
41.5 RL15 
I stopped here and went to Varget, thinking that maybe my rifle didn't like RL15 41.5 Varget 
Primer hole from the Varget round (second from the bottom) 
I am stumped. My thoughts are that there in insufficient headspace, causing the rounds to show the signs of high pressure( ejector marks, shiny brass spots along the bottom). |
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Get someone else to shoot the rifle. Get it onto a good benchrest if possible, however, a good bipod is not a serious detriment to accuracy if you know how to use one. Two of your last targets show a lot of horizontal stringing, indicating lack of compensation for the wind. Most of the rest show a lot of vertical dispersion, indicating a problem with your rest. Also check the scope for secure mounting, and you should probably try yet another scope.
There is a good chance the rifle is shooting to its capability. I'm still not impressed by the primer extrusion into the firing pin channel. That popped primer is probably caused by low pressure, not high pressure. The edges of all those primers are rounded, and the loose one probably popped out because the case was holding to the chamber wall with enough friction to keep the case head from contacting the bolt face. I doubt that signs of high pressure are caused by excess headspace unless you are pushing the case shoulders back too far, like over 10 thousandths of an inch. Ultra flat primers are also caused by low chamber pressure. The case fails to inflate sufficiently to grab the chamber wall, the case is off the bolt face just long enough for the primer to start to come out, then the case slams into the bolt face smashing the primer as flat as load with excess pressure. Does the bolt carrier engage the gas tube without interference or binding? Heck, is the barrel nut tight? |
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AR10 rifles need close to 70 lbs. of torque on the barrel nut, twice as much as an AR15. Did you torque the barrel that tight?
Because they have so much more recoil I also bed the receiver using high temperature wicking grade Loctite. I'm going by memory since it's been several years, I think it was Loctite 609. What powder measure are you using to throw the charges? One primer clearly shows leaking gas around the primer's edge. I would drop the charge even more. Try 40 grains even of RE-15, IMR-4064 or Varget and see how it shoots. Try hand weighing each charge. See if you can get some chronograph readings, I would consider 2550 fps to a maximum of 2600 fps as a reasonable top velocity from a 24" AR10 shooting 175 grain SMK's using Lake City brass. 2500 fps is perfectly acceptable and usually very accurate with Lake City brass. Try 168 grain Sierra Match Kings with up to; 41.5 grains of IMR-4064 40.5 grains of IMR-4895 39.0 grains of IMR-3031 39.5 grains of H4895 43.0 grains of WW-747 40.5 grains of AA-2460 It might be that your rifle simply doesn't like 175's. |
| Www.photobucket.com/kabooom Reduce powder charge for LC brass, by 2 full grains of powder. If you still have pressure signs at the starting load, return firearm for repair. |
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This may sound strange but last fall I had this exact same issue while using a Larue mount and a good quality vortex PST scope. I could not figure it out for the life of me. I didn't have hot loads like yours but my accuracy was all over the place and I could not figure out why.
I may be wrong because I can't tell from the smaller photo you have posted, but check your rail and make sure that any of your attachments you have, IE: fore grip, rail sections etc. don't have the screws that attach them to your rail protruding threw and touching against your barrel. In my case it was because the narrow profile MI rail I was using and a heavier Larue stealth barrel. It took me a couple of range trips to finally figure this out one day after mounting and remounting different scopes and mounts. 
I would also definitely listen to the other posters here because those loads look like they are way too warm. |
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Op,
In your last pic with the primer with the hole in it. Can't quite make it out, but are you chamfering and deburring your case necks? I went back and read that they were trimmed, but nothing about deburring. Is that metal shavings around the neck? If you are scraping the jackets while seating, they will never fly straight or accurate. Just a thought. SY |
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Quoted:
Op, In your last pic with the primer with the hole in it. Can't quite make it out, but are you chamfering and deburring your case necks? I went back and read that they were trimmed, but nothing about deburring. Is that metal shavings around the neck? If you are scraping the jackets while seating, they will never fly straight or accurate. Just a thought. SY I've had nasty double feeds where the bullet looked pretty mangled and it still went into the group with the others (100 yards), just saying. |
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when you zero'd the rifle in the 2nd set of pics you didnt post a picture of how factory ammo grouped?
if factory ammo shoots like crap too then proceed to the next steps. that will tell you if the problem is the rifle or your handloads. those are some real pressure signs for sure. provided factory ammo didnt group if it were me I would break the rifle down and pull the barrel off and take a look. clean it real good put it back together and check headspace Then try a group with some iron sights or a known good scope from another rifle. then move to evaluate your handloads at the lowest start data |
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so far looking at your pics and reading your data it seems you like hot loads? start from scratch using the "ladder" method or "OCW" method. these will help determine what's hot for your gun and help you find an accuracy load. all the pics of your brass show you are near or at overpressure! how long have you been reloading? also might try some GOOD factory ammo to see how it shoots(federal, remington and such), not the cheap ass crap. Bruce |
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The scope mount is a PA extended mount. I am going to start with the most likely issues here, as multiple people have suggested, with the barrel torque and rail clearance. I stripped the rifle down and checked the barrel nut and it didn't take much to get it off. I assembled this rifle myself and I suspect that I didn't use enough torque when putting it together. I tightened it down to 70lbs, but now I have the issue where the screw holes won't line up, either being too loose or tight. I have some shims coming in, but they won't arrive until I am back out in the field( so expect an update around the end of May). Once that is fixed, I plan on moving my keymod slots around, ensuring no possible contact between the slots and the gasblock, especially when loading the bipod and slighting flexing the FF rail.
For all rounds, I have chamfered, decrimped and deburred the cases, all being trimmed to 2.005". I can't comment on why that happened. I would hate if this rifle didn't like the 175's as I intend to shoot this rifle past 600M and heavier seems to be the best bet. |
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To the issue of barrel nut torque:
I have an Aero .308 gun that I built. I've only had occasion to put it through one range session. It did not shoot nearly as well as I had in mind. I ran a box of XM80, a box of Prvi "match" (168 gr), and a box each of PMC and Federal Gold match. (Both were 168 SMKs. Ordered from SG ammo, the federal was supposed to be 175s but they sent the wrong stuff). I was just getting the Vortex Viper PST sighted in (it's in a LaRue mount). I didn't measure the groups but suffice to say they weren't great. When I assembled the gun I followed the instructions that came with the hand guard and barrel nut (Odin) and tourqued to "40-50" ft-lb. I wonder if this could be causing the issue? Should I retourque to 70 as mentioned here? |
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The accuracy load with your components is going to be about 42.5gr Varget at 2.775 COAL and about 42.8 at 2.810 COAL. This is fairly hot, and will leave some ejector marks. But it shoots sub-MOA (in rifles capable of doing so) and is 'safe' in every single .308 rifle I've ever tried it in: 700SPS, 700P, SCAR-17, M1A, AR10T, Noveske N6, SBS Tactical, Colt 901, POF, SR-25.
I consider this a 'match plinking' load. I've posted the full details above. You'll like it. |
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