A little help please

[AMGtuned]

Ok gents, this is gonna be long winded. I've been in front of the bench or chrono all day and I'm getting a little frustrated.

Rifle: Aero AR10, .308, 20", 1:10, round count is at 250 now.

Hornady brass, hornady 168gr match, Varget, CCI 200, powder throw then tuned using RCBS 505 and trickler.

I loaded a ladder from 40.2 to 42.9 in .3 increments. Had a small flat at 40.8-41.1 at 2492 and 2496. Then another beautiful node from 42.3-42.9. Velocity stayed quite consistent; 42.3 @ 2610, 42.5 @ 2608, and 42.9 @ 2616.
So I then loaded an OCW at 42.2, 42.4, 42.6, and 42.8. Groups ranged from 1" to 1.5". ES was all over the map and SD's were in the mid 20's. Wondering what I did, I realized there was some mixed brass in there. Definitely makes a difference in velocities. So I selected 10 more pieces of Hornady brass, and loaded all 10 at 42.5 (the higher side of my high node). Average Velocity was 2598, ES 54.9, SD 18. Seems ok, but my group was 2" at 100! Wal Mart ammo has been the only thing I've ever fired that does that crap. What happened? My 42.2gr group was exactly 1", but avg velocity was 2564 and I wanted 2600 or faster. I have fired ammo at 2700+ with 150gr through the rifle and it took it well, but i want to use my stockpile of 168gr Hornady. Advice/input appreciated from those of you that have spent a lot of time doing this @spife7980 @Subwrx300 @sirhrmechanic @anyonewhowillhelp
Thank you for hanging in through this read.

 

[AMGtuned]

And because everyone loves gratuitous gun porn.....here she is

 

[sirhrmechanic]

Assuming you are full-length resizing and Small base?

Are your bullets seated out as far as you can and still getting them into the mag? Is the ogee on them close to the rifling?

My AR-10 is about as accurate as yours. It is hard to get it under 1". I've done it, but never consistently. It's a good 1" gun, though.

Have you tried cam 'locking' pins between upper and lower? I found that helped a bit on mine.

I have not used Varget. But have used 2520 which (and I'd have to look this up) is pretty much the most best-metering powder I've used for .308. When you can get it.

You didn't say if your Match bullets were HP... but that's what I prefer. Not the plastic tip.

Just some thoughts.

Cheers Sirhr

Oh... Very nice looking rifle! Sounds like you are on the right track!

 

[AMGtuned]

I should have been more specific, Hornady projectiles are 168gr match HPBT. I loaded rounds to OAL of 2.8", cant go much longer, if at all, due to pmag size. Full length sized using RCBS die. Not sure of locking pins, but I have adjusted the screw under the grip to take some of the "slop" out of where the receivers mate. I do not have a comparator to measure distance to lands, just going by spec, and limited by mag size. Hoping to stay at, or under 1" at 100, so I can possibly use it for longer range fun when the bolt guns are taking a nap. Thank you

 

[Subwrx300]

Ok gents, this is gonna be long winded. I've been in front of the bench or chrono all day and I'm getting a little frustrated.

Rifle: Aero AR10, .308, 20", 1:10, round count is at 250 now.

Hornady brass, hornady 168gr match, Varget, CCI 200, powder throw then tuned using RCBS 505 and trickler.

I loaded a ladder from 40.2 to 42.9 in .3 increments. Had a small flat at 40.8-41.1 at 2492 and 2496. Then another beautiful node from 42.3-42.9. Velocity stayed quite consistent; 42.3 @ 2610, 42.5 @ 2608, and 42.9 @ 2616.
So I then loaded an OCW at 42.2, 42.4, 42.6, and 42.8. Groups ranged from 1" to 1.5". ES was all over the map and SD's were in the mid 20's. Wondering what I did, I realized there was some mixed brass in there. Definitely makes a difference in velocities. So I selected 10 more pieces of Hornady brass, and loaded all 10 at 42.5 (the higher side of my high node). Average Velocity was 2598, ES 54.9, SD 18. Seems ok, but my group was 2" at 100! Wal Mart ammo has been the only thing I've ever fired that does that crap. What happened? My 42.2gr group was exactly 1", but avg velocity was 2564 and I wanted 2600 or faster. I have fired ammo at 2700+ with 150gr through the rifle and it took it well, but i want to use my stockpile of 168gr Hornady. Advice/input appreciated from those of you that have spent a lot of time doing this @spife7980 @Subwrx300 @sirhrmechanic @anyonewhowillhelp
Thank you for hanging in through this read.

Whew... That's a tough one. It makes me think that something is changing in barrel. Couple of questions:

What chronograph?
Rounds since last clean scrubbing?
How was ejection pattern?
Barrel a Teludyne? Whose blank?

It sounds an awful lot like one of the following: inconsistent ignition (hammer force not strong enough), barrel starting to carbon up (which will stabilize at some point and stay consistent) or possibly gas port starting to erode a bit and causing a "rough" spot in barrel.

My 224, 223 and 6.5 gassers all went through a period like this with poor ES/groups between 100-250 rounds. Even my bolt guns have done it but less severe.

I think it's barrel starting to form carbon ring: in both my match rifles and 2 gassers, if I scrub them clean the pattern looks like this:
From 3-40 rounds groups are very tight, SDs great (single digits for almost all rifles).
From 40-100 SDs increase a bit (10-18) and speeds fluctuate even for known loads.
From about 100 onward, the speeds jump up about 10-20fps and SDs come back to normal range (4-10).

The carbon in the throat seems to need a period to cool, harden and normalize before staying consistent. If carbon ring is forming, it can cause all sorts of weird crap, including the high SDs you experienced.

And on a side note, while I really like Hornady brass overall, I only use same lot Hornady. I have a box of 6.5 mixed lot brass that catches any piece of brass that I'm not 100% certain is from same lot.

If I shoot a known load from that lot for practice rounds, my SDs are easily in the mid teens and ES in the 40s even with bolt guns using Bartlein, Kreiger and Criterion barrels. Then, the same day, I shoot my match load and match Hornady brass ... SDs are 6-8 again.

Hornady is really good overall but their lot to lot consistentcy is about as good as Wolf or Tula. Mix lots together and you could easily see what you are experiencing. If you can find 20 PC's of same lot brass, that will help you narrow the culprit down quickly.

 

[AMGtuned]

@Subwrx300 , thanks for your informative reply. My original post said round count was 250, that is a typo. Round count is 150, so I could be seeing some speed changes there. AR15 settled at less than 200, was hoping this would do the same. Chrono is a Shooting Chrony Beta master, only a few weeks old, seems to work well. Positioned at 10' from muzzle on a tripod. Barrel is definitely wrapped (good assumption ?), and the blank used was a lothar/walther 20" heavy profile, with a rifle length gas system. Once you mentioned it, I dont believe I have thoroughly cleaned the barrel since it was jacketed. I was waiting to feed a few through it, but that's probably not helping my reloading procedure. Overall, I have had good luck with the hornady brass in my bolt guns, but it definitely seems to vary in my gasser. I'll scrub it down, and fire some factory ammo through it. Maybe that will change its attitude?

 

[AMGtuned]

Update for those interested: qorking off some great advice from @Subwrx300 , I scrubbed clean (dont believe I had yet at all) , then proceeded to test my loads again. I also fired some xm80 i have in bulk for a control. Still couldn't keep my numbers down, and groups tight. So, i reloaded my original ladder using only 41.9-42.4 in .1 increments. Barrel speed had DEFINITELY changed, as i was seeing faster speeds, in lower charges than my initial test. Using that data, and knowing i wanted around 2600fps, I loaded up a smaller ocw using only 41.9 and 42gr, and 5 rounds each. Long story short, 42gr got me and average velocity of 2611fps, ES of 20.2, and SD of 9.1! It also grouped very nicely, at 100 yards, inside .75". Very psyched! Thank you all for the input, I now have my first known load for this little sweetie, and I think shes gonna be a fun one!

 

[bax]

Picking up on the gratuitous comment theme ... a .308 with 168 gr bullets and Varget will achieve roughly 2,625 fps out of a bolt gun with a 24-inch barrel - more or less. You are shooting a 20-inch barrel. Maybe when the bullet leaves the muzzle, not all of that varget has burned up. If you want the 24-inch velocity from a 20-inch barrel, maybe try a faster powder? When the round goes off, do spectators see a fireball?

The muzzle-end of that free-floating barrel with sights 3/4 of the way out, a flash suppressor, and a gas tube is doing a jig when that round goes off. You need a node, it sounds like you found one so good on ya. My AR-10 hits a 6-inch plate at 600 yards most of the time, they are a blast to shoot. Enjoy.

 

[AMGtuned]

Picking up on the gratuitous comment theme ... a .308 with 168 gr bullets and Varget will achieve roughly 2,625 fps out of a bolt gun with a 24-inch barrel - more or less. You are shooting a 20-inch barrel. Maybe when the bullet leaves the muzzle, not all of that varget has burned up. If you want the 24-inch velocity from a 20-inch barrel, maybe try a faster powder? When the round goes off, do spectators see a fireball?

The muzzle-end of that free-floating barrel with sights 3/4 of the way out, a flash suppressor, and a gas tube is doing a jig when that round goes off. You need a node, it sounds like you found one so good on ya. My AR-10 hits a 6-inch plate at 600 yards most of the time, they are a blast to shoot. Enjoy.

Haven't shot it with anyone yet, so no idea on a fireball. My initial test revealed the node to be higher than it actually was, due to being a new barrel. After cleaning, and some foulers, a new ladder test revealed the node almost a full grain less. 20 shots averaged 2611fps with an ES of 20. I'm happy with that speed. There are no sights on my barrel or handguard (?), and if there is one thing I am CERTAIN of, my barrels do not "whip". My bolt guns are silly fast, without pressure signs. Those usually end up getting ammo loaded wayyyyyy below book listed speeds, to achieve the same, or faster. My R700 tac, and gen 1 RPR, both have 20" tubes and sling ammo accurately and high speeds. Win mag has a 26" tube, because, well, magnums should be savage beasts. And you can get some pretty fast numbers out of that. I launch 150gr out of that, at well over 3000fps. The technology behind the barrel system takes out a lot of the "chasing" (for lack of a better term" that we have to do when loading ammo. No more trying to "time" the round to the harmonics of the barrel, because it just doesn't whip. I appreciate the feedback, and, like you said, I'm looking forward to banging some steel with this bad boy. Her "twin", my 5.56, is a hammer on steel. Having no problems hitting 8" plates, at 450, in 15mph cross wind, with even Winchester white box 55gr. Happy shooting

 

[918v]

Which Hornady brass? The one that weight 165grs? If so then you’re loading them too light. Go up to 44.8grs or so.

 

[AMGtuned]

Which Hornady brass? The one that weight 165grs? If so then you’re loading them too light. Go up to 44.8grs or so.

They're the ones from American Whitetail, not match. I have some match, but not nearly as much. When I got up to 42.9, I was getting some funky fluctuations in my speeds. I had some bolt gun handloads; in my stock, that were 45gr of IMR4320, with nosler 150gr Ballistic tip, that average 2750 from my bolt, but blew primers out when I tried them in the AR. First shot registered 2800, next one blew the primer onto the table upon ejection. I stopped there. Why would I want faster than 2600?

 

[918v]

You’re the one complaining about the accuracy. The charge weights you’re running are inaccurate. The accuracy loads are around 45grs, 43.5grs, I haven’t played lower with 168 and Varget. You’re running an inaccurate charge weight and complaining about accuracy then asking why would a higher velocity be beneficial??? WTF?

 

[AMGtuned]

You’re the one complaining about the accuracy. The charge weights you’re running are inaccurate. The accuracy loads are around 45grs, 43.5grs, I haven’t played lower with 168 and Varget. You’re running an inaccurate charge weight and complaining about accuracy then asking why would a higher velocity be beneficial??? WTF?

Wait a minute, what? I used the fast loads to TRY. I did the research, performed the tests, and my subsequent posts revealed that I HAD found the correct node. And was happy with 2600fps as my target speed. How can I argue with .75" groups, an SD of 9, and 2600fps? I WAS worried about accuracy, when I created the original post. After receiving HELPFUL advice from another member, my problem has been solved. 42 gr netted me 2600, why would i even consider trying, what I believe to be BAD advice, and up my charge 2 full grains? Do you want someone to get hurt? Who's accuracy nodes are that high? Mine certainly are not.

 

[AMGtuned]

And I only asked you a simple question; why would one want any faster than the 2600 I posted I got, and was happy with, in a gas gun?

 

[918v]

You tried 43.5grs? Really?

 

[AMGtuned]

I hit my target velocity of 2600fps with 42. My question was, why? Not trying to be a dick here, but I'm not understanding the why. Seems as though most gas gun loads hover the same speed, and based on what I've read, 2600 gets you places with a .30 cal. After my original posts, you suggested 44.8, based on my case choice. Then proceeded to belittle my findings, with no evidence or facts, other than what is quite possibly YOUR personal findings. I started this thread looking for insight; expecting, from a good bunch of enthusiasts, SAFE, practical, advice. Just not sure where this has come from. Regardless, thank you for turning this thread into a playground bully match, instead of answering the simple question of, "why?" What are the benefits of trying for more? Heckle the guys shooting 2400fps from 24" tubes. Maybe they're willing to attempt some facial scars. You've opened my eyes to the fact that not everyone on here is as willing to be helpful as others.

 

[Subwrx300]

You tried 43.5grs? Really?

While there might be a higher node for some rifle/barrel combos, @AMGtuned 's combo may not reach that node without causing some issues with early unlocking/gas timing. I have a gas gun with a Dracos barrel (very similar to his) and it does not respond that well to the upper nodes for most bullets. Generally, I've needed to reduce loads to either 1-1.5gr less than known nodes to keep precision without causing flyers/odd random shots from creeping into a specific load.

Example: my bolt 6.5CMs run 2780-2810 with 140s no problem but my gas gun needs those closer to 2650-2700 to run well. So I opted to push a lighter bullet (123gr) at 140 velocities of around 2800-2830. Its a different caliber than AMG is running to be sure, but I have yet to build a gas gun that will run same loads as bolt gun with similar precision. I've always needed to reduce load to achieve precision I needed from the system.

He could certainly try the higher nodes but would likely require additional tuning of gas system/buffer/spring to keep timing without early bolt unlock and swiping.

 

[918v]

45.8grs of Varget in a 165gr Hornady case does 2780 FPS in a 26” bolt gun. 43.5grs in a 176gr FC case does 2720 FPS. But he’s getting 2600 FPS out of a 20” gas gun using only 42grs. Is he using 185gr cases? I cNt get that kind of speed out of my 21” gas gun with that little powder.

 

[AMGtuned]

I am currently loading ammo in question. I weighed cases for you @918v. They're all primed, so I weighed the primers too. They've all been fired twice, if that makes a difference.
Primed case: averaged 190.2-190.4

CCI 200 lrp: 5.4

If my math is correct, give or take .2gr, it appears I'm using 185gr cases.

 

[918v]

Then you should be happy with your velocity.

 

[AMGtuned]

It appears the "match" brass is the 165gr case. I had some on hand. I am, and the only reason for my choice in Varget, had been its consistency across calibers and platforms. I'm able to load .223 69gr Matchkings with 24.1 and average 2600 from a 16", and I can load for my .308 rifles with it also.

 

[bax]

... a new ladder test revealed the node ...

Are you telling me that as you increase your powder charge the group size never changes? That isn't what your original post said. And what is this in your comment about revealing a node? The node MEANS that the bullet emerges from the barrel at a time when the barrel is pointing in the same direction. Shorter is stiffer and that helps but all barrels vibrate and if you shoot when the muzzle direction is rapidly changing, you get big groups.

 

[Subwrx300]

Are you telling me that as you increase your powder charge the group size never changes? That isn't what your original post said. And what is this in your comment about revealing a node? The node MEANS that the bullet emerges from the barrel at a time when the barrel is pointing in the same direction. Shorter is stiffer and that helps but all barrels vibrate and if you shoot when the muzzle direction is rapidly changing, you get big groups.

I don't think @AMGtuned was saying that at all. But a "node", which is usually found at a specific velocity range, can require a different charge to stay in the zone as barrel speeds up/slows down.

I think he was saying that barrel technology today affords us a lot more repeatable precision for the dollar than 20 years ago.

Here's an OCW/Audette ladder for two bullets covering nearly a full grain of powder in one and .5 grains in the other with a 6.5CM and groups change but nearly all are at or under 1/2 moa at 400 yds. I don't have to "chase precision" as most loads virtually all reasonable charges will produce sub minute precision.

Doesn't mean that they stay the same with Al charges but precision is easier to find/maintain with modern quality barrels and equipment.

 

[bax]

But a "node", which is usually found at a specific velocity range, can require a different charge to stay in the zone as barrel speeds up/slows down.

I think he was saying that barrel technology today affords us a lot more repeatable precision for the dollar than 20 years ago.

And you posted a picture that proves my point. Your top target: 41.7 grains of powder, 2.4 inch group. 41.9 grains, 0.83 group. Assuming, for the sake of argument, that these results are repeatable, when you use the 41.9 charge the bullet emerges from the barrel at a point in time when the barrel has instantaneously stopped moving so you get a smaller group. With 41.7 grains, the bullet emerges a a slightly later time when the barrel is moving so you get a bigger group. If the results are not repeatable, then it is the shooter or the weapon causing the group size.

416 stainless hasn't changed. The barrel profile didn't change. A shorter barrel moves less than a longer one - I would call that a more stiff barrel.

The key difference over 20 years is that specific cartridge - the 6.5 crede is an awesome round that shoots like a laser beam - similar to a dasher or 6PPC. I suppose, without any evidence, that the 6.5 Crede causes less barrel motion -or- y'all shoot known good brass/bullet/powder/primer combinations that other cartridges cannot match. I cannot make a 308 shoot like that regardless of materials or technology and I don't mind a bit. If it was dependent on modern materials or barrel technology then I could make a 308 shoot like that.

 

[AMGtuned]

Are you telling me that as you increase your powder charge the group size never changes? That isn't what your original post said. And what is this in your comment about revealing a node? The node MEANS that the bullet emerges from the barrel at a time when the barrel is pointing in the same direction. Shorter is stiffer and that helps but all barrels vibrate and if you shoot when the muzzle direction is rapidly changing, you get big groups.

My barrel was almost new. Round count was low (120-150) during my first test. When ALL charges tested, I repeat, ALL charges tested, would not produce low SD and ES, i reached out for help. ALL early charge weights produced sub 2" groups, and i knew that both my weapon, and myself as a shooter, were capable of better than that. A good scrubbing, then shooting some factory ammo to increase round count and foul the barrel back up, I decided to try the first batch of charge weights again. At which point, I was getting FASTER speeds from the SAME charges as first test, but still producing 2" groups, at the higher speed. Curiosity and fellow encouragement led me to reload my ladder test. First ladder revealed a "node"; or whatever youd like to call it (flat spot in velocity within a certain charge range), in the 42.5-42.8 range (2615 was the speed at that time. After cleaning and fouling, the same components in a new ladder, revealed that the "flat spot" in velocity (coincidentally 2600ish again), was at 41.9-42.2. Loading within that range tightened my groups significantly as well as ES and SD. Maybe were both right? This thread is now beating me to death. Maybe I shouldn't have said my barrel "does not" whip; whereas I could've said, "not as much as yours". But I'm not a dick, and get encouraged and more confident by replies such as your first one. All in all, it was interesting to see that rounds still grouped, with crazy spreads on the chrono. When charges were bringing speeds closer to 2700, POI raised an inch, but the rounds still grouped, just not as tight as I wanted. I think I'm rambling now

 

[AMGtuned]

Descent Into Madness: Intro to Teludyne Tech and the “Straight Jacket” - The New Rifleman

Over the last few years, the quality in the A15 barrel market has improved substantially... even basic, free floated barrels have been shown capable of 1 MOA or better with quality ammunition. Not only has the quality improved, but so has the pricing. In spite of any advancements the market has...

www.thenewrifleman.com

 

[Subwrx300]

And you posted a picture that proves my point. Your top target: 41.7 grains of powder, 2.4 inch group. 41.9 grains, 0.83 group. Assuming, for the sake of argument, that these results are repeatable, when you use the 41.9 charge the bullet emerges from the barrel at a point in time when the barrel has instantaneously stopped moving so you get a smaller group. With 41.7 grains, the bullet emerges a a slightly later time when the barrel is moving so you get a bigger group. If the results are not repeatable, then it is the shooter or the weapon causing the group size.

416 stainless hasn't changed. The barrel profile didn't change. A shorter barrel moves less than a longer one - I would call that a more stiff barrel.

The key difference over 20 years is that specific cartridge - the 6.5 crede is an awesome round that shoots like a laser beam - similar to a dasher or 6PPC. I suppose, without any evidence, that the 6.5 Crede causes less barrel motion -or- y'all shoot known good brass/bullet/powder/primer combinations that other cartridges cannot match. I cannot make a 308 shoot like that regardless of materials or technology and I don't mind a bit. If it was dependent on modern materials or barrel technology then I could make a 308 shoot like that.

Totally get what your saying and completely agree that precision changes with different charges due to a number of factors including barrel time, harmonics and more. I was only saying that you may have misinterpreted what AMGTuned was saying in his post about node moving. His node changed due to barrel speeding up and carbon forming in barrel between the two tests he ran.

After he scrubbed barrel and reshoot for third time, the results matched up much better and became more repeatable.

While steel hasn't changed, more barrel makers have invested in better equipment, allowing them better machining of barrels/rifles. As a result, it's easier to tune rifles for precision than it has been in years past. Bullets are more precise, barrels are better, (some) cartridges are better and tools like SnipersHide make it easier to find information faster. All of which contribute to improved precision faster.

Only reason I put up that OCW test was to show that for a lot of guys, 1/2moa would have been good enough from the start. I could have loaded any one of those charges and shot well to distances beyond 800-1000 yards. I know what my limitations are as a shooter, so when I hit .3-.4 MOA, I call it a day and keep that load going for matches.

All good stuff though and glad we were able to help AMG get some ideas for his load and, in this case, it worked out!