Gas guns and EldM problems?

[CST]

I've got a ar10 6.5 cm we have been shooting with American gunner 140 with no issues for years now.
I am now reloading 140gr. EldM with H4350 in annealed once fired Hornady brass with about .003 neck tension loaded to 2.800. Its been totally reliable but I suddenly noticed occasional wild flyers. Sometimes a round would impact 6-10 inches off to the side. Otherwise the groups are all sub moa.....at 100 yards.

Everything has been torqued and rechecked. Anyone have any guess on why occasional fliers occur? It doesn't seem to happen with the American gunner. I have no baffle strikes thru the surefire can so they are coming out straight. It's a lilja barrel with approx 1000 rounds thru it.

All I can assume is something is wrong with neck tension or the EldM tips are getting messed up so bad it's throwing off the shots.

 

[FredHammer]

What distance are the flyers 6-10" off bull?

Eliminate the variables of the bullet first:
Neck tension, even heavy, doesn't cause flyers.
Gyroscopic instability of the bullet causes flyers. (Or equipment failures, test second since the American gunner worked)
You can weigh and measure each bullet for consistency and shoot the cream of the crop to see if this still occurs.
You can also shoot that cream of the crop against the American gunner.

The BTHP might be shooting better because the ogive is further forward and having less jump to the lands.
The ELDM ogive is farther back, and then when restricted by magazine length, has too much jump to the lands.
I would think if the DTL is off, they would all be fucked up though. You might be right at that cusp of good jump though.

Tip deformation, I've read reports from manufacturers, like Barnes, and some older material that tip deformation doesn't have an impact on precision. Then Hornady switched to non melting tips because they claim they are melting in flight...So then I guess tip deformation matters. LOL See the mindfuck about this now?

I'd chamber a few rounds and eject to see if those ELDM tips are getting jacked up from the extension cuts. I think tip deformation matters, but that could be my OCD bias.

Next step would be to evaluate the equipment and shooter. That latter variable can get touchy!

 

[TheOfficeT-Rex]

Drop the bolt on a couple rounds then eject them to make sure the feed ramps aren’t jacking up the tips. I’ve seen some that actually snapped some tips off.

 

[Rocketvapor]

Check for copper at the gas port.

 

[FredHammer]

Drop the bolt on a couple rounds then eject them to make sure the feed ramps aren’t jacking up the tips. I’ve seen some that actually snapped some tips off.

...and "They" back in the day warned of shooting exposed soft lead tipped bullets in gas guns, but plastic shredded tips are ok? LOL

 

[FredHammer]

Check for copper at the gas port.

That was a strong thought, and I've lately been doing a lot of gas port evaluation, but I was still riding on the claim that the American gunner didn't have flyers...maybe...

 

[CST]

Thanks for the advise....I wouldn't be concerned if I got the fliers that open em up to 1+....but I'm getting fliers im getting are complete off target... Again. ......6-10inch or more from point of aim....this is at 100 yards to clerify

 

[Hecouldgoalltheway]

That was a strong thought, and I've lately been doing a lot of gas port evaluation, but I was still riding on the claim that the American gunner didn't have flyers...maybe...

That american gunner ammo is an anomaly. I've shot it in probably a half dozen rifles, and it's probably the most consistent factory ammo I've ever seen. (I'm speaking specifically about the 140gr 6.5cm variety.). I bought a pile of it pre-covid for less than $1 per round, but didn't realize how good it was until it was gone or ridiculous. Had I known how consistent it was, I would have bought 10k rounds. You'll struggle to do much better than it with handloads. Of course, user experience may vary..

 

[spife7980]

Get a bigger target board, catch those fliers and see if they are round holes or if they are oblong or spewing lead.

Also, clean your barrel.

 

[FredHammer]

Thanks for the advise....I wouldn't be concerned if I got the fliers that open em up to 1+....but I'm getting fliers im getting are complete off target... Again. ......6-10inch or more from point of aim....this is at 100 yards to clerify

Oh boy. I know you said American gunner didn't "seem" to do this. Outside of this I am thinking an equipment issue of some sort. With what HCGATW said about the gunner ammo, I am thinking equipment.

 

[Rocketvapor]

I've shot .224 80/88 ELD with broken tips for 100 yard range time rather than toss them.
Groups opened up some but not terrible.

 

[CST]

Could serious bullet setback from the forces of the feeding or weak neck tension cause a sever flyer like that?

 

[Ledzep]

Tip breaking is something you can encounter with semi-autos. It's not isolated to one brand either. It's another one of those things "It depends". Feed cycle, bolt speed, magazine presentation... blah blah blah. Adjustable gas blocks (mild as possible to reliably cycle) and the magazine sitting as high as possible seems to be the best situation.

It's not especially common, but we've seen it. Stuff with large case body to bullet diameter ratios and long skinny ogives seem to suffer the worst (224 Valk, 22 grendel, 22 GT, 6 GT etc.). We have also had isolated cases of tips with less-than-ideal properties coming from the molders. It's something that myself and others are actively working to improve to make it even less common. FMJ, BTHP, and A-tips eliminate the chance. The non-heat shield tips (older Amax, SST, Vmax, etc.) is much more likely to get mangled and not shear, but comes with its own set of issues for long range shooting. Mangled/scratched/deformed tips range from "can't see a difference" to very very different. The most common tell-tale sign is at 600+yd you'll have a round land WAY low.

 

[FredHammer]

Could serious bullet setback from the forces of the feeding or weak neck tension cause a sever flyer like that?

Yes. However, .003 NT is enough to keep them in place. Over .004 is reported to be diminished returns due to brass elasticity issues. (Brass losses the tension)

To check, chamber the rounds as mentioned previously check the tips and check your length.

Also describe your method of setting & checking NT (Interference fit technically)

 

[Waco Kid]

Good timing on this thread, and good info! I’ve been wanting to take a 6.5g ar hunting and had similar issues to op. Shoots bthp of different flavors great, but I tried some SST’s out and they are all over the place. Maybe due to the tip deformation mentioned above? This was with factory Hornady Custom, not hand loads.

 

[Ledzep]

Let the rifle cycle and pull a few rounds at random and see what they look like. In general, I'd say that dispersion issues aren't related to tips getting dinged or scratched. They gotta be pretty smashed and usually it's more of a long-range drag issue than it is close-range dispersion. It's usually more a barrel+powder combination that is happy or unhappy. I have also noticed that loads are much more sensitive to muzzle devices in semi-autos. You can see distinct, repeatable dispersion profiles when swapping through multiple brakes/cans with a given load. As an example, 108 Factory match 6mm ARC in my PRS rig shoots awesome with a Hellfire Match brake and poopoo with my Ultra 5. Conversely, my 109+Varget load HAMMERS with the ultra 5 and is erratic with the HF match brake. That has been my general takeaway from the last 2 years of shooting gas gun for precision, lots more nuances and BS that wouldn't matter with a bolt gun that absolutely matters with a gas gun. Adjustable gas is another thing that can really put a damper on erratic fliers.

 

[FredHammer]

That american gunner ammo is an anomaly. I've shot it in probably a half dozen rifles, and it's probably the most consistent factory ammo I've ever seen. (I'm speaking specifically about the 140gr 6.5cm variety.). I bought a pile of it pre-covid for less than $1 per round, but didn't realize how good it was until it was gone or ridiculous. Had I known how consistent it was, I would have bought 10k rounds. You'll struggle to do much better than it with handloads. Of course, user experience may vary..

$648 ($1.30 per round) shipped 500rnds decent today?

 

[UpSideDown]

The 140gr American Gunner also performed way better than I expected in my Tikka. I bought it as cheap practice ammo and pulled a 1/8 MOA group out of it after some break-in. It was slooooow though, and I think the BC was was under advertised.

 

[FredHammer]

The 140gr American Gunner also performed way better than I expected in my Tikka. I bought it as cheap practice ammo and pulled a 1/8 MOA group out of it after some break-in. It was slooooow though, and I think the BC was was under advertised.

Oh do please specify amount of rounds for that 1/8" MOA group. I said 1/4" MOA one time and the goblin haters automatically assumed I meant 150rnds into that .25MOA group. It is still a point of contention to this day, even after it was established it was 3-5rnd groups. Haters gonna hate.

 

[AZLong]

I would check the runout and jump on those rounds. As mentioned, if the longer bullets have a further jump, any runout would be amplified.

 

[UpSideDown]

Oh do please specify amount of rounds for that 1/8" MOA group. I said 1/4" MOA one time and the goblin haters automatically assumed I meant 150rnds into that .25MOA group. It is still a point of contention to this day, even after it was established it was 3-5rnd groups. Haters gonna hate.

Bro, it was a 4 round group, it's the only way these things exist


I just didn't think I needed to say it....

 

[FredHammer]

Bro, it was a 4 round group, it's the only way these things exist


I just didn't think I needed to say it....

Most rational people don't, but this place is full of the irrational...

 

[UpSideDown]

For realsies though, the 140gr AG is the first round I took out to 900yds. It was surprisingly consistent and accurate and was regularly a 1/2 MOA round in all my groups if I was doing my part, but it was very slow and low BC compared to the box numbers. This is all pre-covid. I've just started seeing it around again.

 

[FredHammer]

For realsies though, the 140gr AG is the first round I took out to 900yds. It was surprisingly consistent and accurate and was regularly a 1/2 MOA round in all my groups if I was doing my part, but it was very slow and low BC compared to the box numbers. This is all pre-covid. I've just started seeing it around again.

Cool. What was it cruising out your Tikka?

 

[UpSideDown]

Cool. What was it cruising out your Tikka?

My numbers say 2,590fps and .222 G7 BC is what I trued it to.

 

[FredHammer]

My numbers say 2,590fps and .222 G7 BC is what I trued it to.

I thought Hornady made that round to cruise 2700-2750. Can you give barrel length and atmospherics?

 

[John Glidewell]

Drop the bolt on a couple rounds then eject them to make sure the feed ramps aren’t jacking up the tips. I’ve seen some that actually snapped some tips off.

This ^^^^^^ I had this happen, went to regular BTHP and no more issues. It was breaking the plastic tips off when it cycled.

 

[Longshot231]

I've got a ar10 6.5 cm we have been shooting with American gunner 140 with no issues for years now.
I am now reloading 140gr. EldM with H4350 in annealed once fired Hornady brass with about .003 neck tension loaded to 2.800. Its been totally reliable but I suddenly noticed occasional wild flyers. Sometimes a round would impact 6-10 inches off to the side. Otherwise the groups are all sub moa.....at 100 yards.

Everything has been torqued and rechecked. Anyone have any guess on why occasional fliers occur? It doesn't seem to happen with the American gunner. I have no baffle strikes thru the surefire can so they are coming out straight. It's a lilja barrel with approx 1000 rounds thru it.

All I can assume is something is wrong with neck tension or the EldM tips are getting messed up so bad it's throwing off the shots.

I've shot .224 80/88 ELD with broken tips for 100 yard range time rather than toss them.
Groups opened up some but not terrible.

Tip breaking is something you can encounter with semi-autos. It's not isolated to one brand either. It's another one of those things "It depends". Feed cycle, bolt speed, magazine presentation... blah blah blah. Adjustable gas blocks (mild as possible to reliably cycle) and the magazine sitting as high as possible seems to be the best situation.

It's not especially common, but we've seen it. Stuff with large case body to bullet diameter ratios and long skinny ogives seem to suffer the worst (224 Valk, 22 grendel, 22 GT, 6 GT etc.). We have also had isolated cases of tips with less-than-ideal properties coming from the molders. It's something that myself and others are actively working to improve to make it even less common. FMJ, BTHP, and A-tips eliminate the chance. The non-heat shield tips (older Amax, SST, Vmax, etc.) is much more likely to get mangled and not shear, but comes with its own set of issues for long range shooting. Mangled/scratched/deformed tips range from "can't see a difference" to very very different. The most common tell-tale sign is at 600+yd you'll have a round land WAY low.

I cannot speak for the AR-10 in 6.5 CM but have an AR-15 in 224V, shooting the Hornady 88 ELDM. Broken tips led to a lot of my fliers. I switched to the Federal GMM 80.5 Bergers. No more fliers.

That's not exactly proof of broken tips. However, when I suspected broken tips, I started chambering the rounds without firing. Then I extracted the rounds and discovered the broken tips.

Maybe you could chamber a round, or several, then extract them. If the tip is broken, then that's your answer.