Pressure Signs - M16 High Power Rifle

[grizlywinkleman]

Primer pocket go/no go gauges are on the shopping list as well. I do get varying resistance when seating primers amd have had to toss a few cases out for being to loose.

To clarify, I do ream the primer pockets with a uniformer on a brass prep station.

 

[Seabeeken]

Cleaned a carbon ring today. Used a new to me water based paste from us products. Made short work of it and was very easy to clean the paste out. Very impressed with it. Worked easier than iosso.

 

[RegionRat]

Can't the base armorers help you out?

Are there any competitive shooters on the base who can help you scope and debug?

 

[Chris F]

arggghhh...I can't contain myself any longer.

I've had a Hawkeye since the days when the price to peek was the cost of a WOA upper...and I can't tell you when the last time I saw a carbon ring in a service rifle barrel. While I don't discount the possibility that a carbon ring in the THROAT can cause pressure signs, but...

The most likely culprit is that he is running up pressures on a thin cupped primer. I'm pretty sure some of those loads exceed SAAMI (yes, I do have a strain equipped upper that I did run pressures on a bunch of N540 loads because of certain Texas shooters). Combine that with CCI400 and those flattened primers are a virtual certainty.

My best advice is to switch to a primer that is proven in Highpower competition; Rem 7.5's, CCI450's, and Fed 205MAR's. Stay away from Rem 6.5's, CCI400's and some will say Win SRP's.
Second best advice; sign up for the NationalMatch.us board where you can bounce questions off experienced Service Rifle shooters.
Third best advice I can give you; ALWAYS choose accuracy and reliability over speed. Nothing wrong with your Varget load if it shoots tight. I've won stuff with Varget at barely over 2600.

...of course you can always get a Teslong (for much less than I paid for my Hawkeye) and some Iosso paste...but I predict that until you change your primers, you'll see the same thing.

 

[grizlywinkleman]

Can't really tap into Army resources. Privately owned firearms are not allowed on cantonment and those types of tools are considered sensitive items so can't really walk away with them

The Teslong that Chris F mentioned is what I ordered. Getting here tomorrow. I will be trying new primers. I tried nationalmatch.us board in the past and didn't get any responses. I thought it was a dead forum.

 

[SSG Graybush]

Hey erbody,

Hoping you all can help me out. I started to refine my typical load as well as try a few other powders in my high power/service rifle M16A4. I was shooting 77gr SMK's in LC brass (mix of years since 2000 not separated), CCI 400 primers, 23.5gr Varget. I would get the occasional AR ejector marks once and awhile but nothing else.

I recently worked some ladder tests with 8208XBR (Top) and N540 (Bottom) with the same components in 2x fired brass. Here are my findings:
View attachment 596973

I started getting increasing pancaking of my primers, ejector marks, and occasional extractor marks/burrs starting at the second load of 8208 and the fourth load on N540. Totally normal in a ladder test right...?

Here is the problem, I loaded up some 10 shot groups of N540 at 24.6gr hoping to get a 600 yard load and 23.7gr of Varget (added .2 gr) hoping to get a little more than 2600 FPS. I first fired a 5 shot control group of 77 gr OTM AAC factory ammo (fly's at about 2815 out of my rifle; it's good stuff!). Everything seemed to have followed the trend of pressure signs. Pancaking is especially more prevalent. Here are a few pics: View attachment 596975View attachment 596976View attachment 596977

I'm shooting a Bartlein Barrel that was manufactured at a time know for premature barrel extension wear out. Could these signs be a sign of that? The 23.7 gr load of Varget shot .863 MOA @ 100 and the function was fine. I've never shot a barrel out but I got the upper from a good friend and have put about 700 rounds through it.

Is my barrel that picky? I wouldn't expect such a drastic pressure sign jump with .2 gr of varget. I will be monitoring the 23.5gr load of Varget at my next practice. Maybe I'm over thinking this and need to just dumb down my loads but it really doesn't feel like I'm reaching for any extreme's. Perhaps I need to be humbled.

Any words of wisdom would be greatly appreciated. Thank you for your time.

Ryan

Stop chasing a factory loads speed. Actually stop chasing speed period. Develop a load development process and stick to it. Run a ladder, find max pressure and a charge weight to start with, then go back and forth between jump and charge weight to fine tune the load. Consistency is king, not speed.
Edit- 23.8 grs of 8208 is the book max for a 69 gr smk I believe, it was also the only load a picky 18" dmr lwrc of mine liked half way decent at .7 moa at ~2750 fps. The ES was meh as well, can't remember off the top of my head. Rifle price didn't match accuracy.
And don't forget, a load developed in cooler weather maybe over pressure on hotter days.

 

[Reelman1]

Suppose commercial loading in mil brass may be the problem. Just supposing, I have had very similar results in wildcatting mil brass.

 

[bamban]

... but I predict that until you change your primers, you'll see the same thing

Yes

 

[jeb405]

I read all replies and will add my experience, not sure if helpful but did not see others refer to this. I learned that my 2 WOA uppers have much shorter throats than other 5.56/223 barrels I have. I was loading at your OAL and periodically got a bullet stuck in bore. Not an issue with all bullet designs, but for sure with 77 SMK it was. If you are right around 0 jump could explain pressures. Not sure if you already know your jump, can't say if your chambers are like mine. Anxious to learn if you find carbon ring or not.

 

[Eric Musgrove]

I am going to chime in because I truly want to help you out. I don't have the extended experience of Bamban because I have been out of the high-power game for 10 years. When I started we still were issued match grade M-14s and then within two years everyone had ARs of some sort. So there was a big learning curve and we all helped each other figure it out for the sake of the team. High-power is really not that much of a precision game. If your able to shot MOA your able to clean the targets and too win matches and that's why the targets are the size that they are.
You have had a lot of suggestions about changing the primers so I want to address the brass and brass prep. Like other mentioned your after consistence here not speed. If you miss the wind call the difference you can gain isn't going to keep you from dropping a point at the long line.
I was able to go distinguished using LC97 brass Win SR primers and 24 grs of Varget for the 200 and 300 yrd lines. There is a big difference in case weight variance in the same year Head Stamp, let alone a mix bag of years. Get all the same year and sort them by 1 gr. lots and color the case head with a sharpie so they stay separated. I had 4 different colors/lots just from LC97 brass. I would suggest getting new brass and cutting out the crimp, I had nothing but trouble swaging pockets. If you need help acquiring one fired WCC brass let me know I can fix this this problem. I retired and left the sport in 2014 but still have lots of stuff.

 

[308plinkerVT]

Okay, lots of good info here to digest. Some personal Highpower rifle reloading experience for you. I've mentioned it in various other places: Zedickers ammo book. He was a master class Highpower shooter and wrote arguably one of the best books out there geared for this topic. Tidbits mentioned I echo: carbon ring, thicker primer cups. David Tubb sells a carrier weight system that will help you with bolt unlock timing, at the speeds/pressures your running at it might help you with a premature failure/separation. Grab yourself a broken case extractor if you don't already have one. You are running in load territory that produces excellent on target results but also is why the "factory" loaded stuff gets crimped in primers. I have seen a single feed 80gr load do the same thing to primers yet produce a 4.5" group at 600yds (with irons), most 77's like to be pushed faster too so head all the signs and keep double checking everything and taking notes and be careful. If you're not annealing and "gently sizing" you might want to look into it. Wouldn't hurt to batch your cases by weight and year, by water volume is tedious but some kind of capacity segregation is important. I'm not sure why you mentioned neck turning, I only suggest it if you're going to bump the shoulder with a groove to take care of the internal brass doughnut that happens with repeated firing. There used to be a cutter for the Sinclair/Wilson trimmer for that internal case neck doughnut if you want I feel a simpler approach. I don't recall if Zedicker applied both every/all the time or not to his cases but both are outlined in the book as steps. One last thing in mind right now, is that chamber a Wylde, 223 or Nato? That ring mark on the loaded round tells me things are a bit tight in there for 77's, Wylde specs work better.

 

[Teri Anne]

Hey erbody,

Hoping you all can help me out. I started to refine my typical load as well as try a few other powders in my high power/service rifle M16A4. I was shooting 77gr SMK's in LC brass (mix of years since 2000 not separated), CCI 400 primers, 23.5gr Varget. I would get the occasional AR ejector marks once and awhile but nothing else.

I recently worked some ladder tests with 8208XBR (Top) and N540 (Bottom) with the same components in 2x fired brass. Here are my findings:
View attachment 596973

I started getting increasing pancaking of my primers, ejector marks, and occasional extractor marks/burrs starting at the second load of 8208 and the fourth load on N540. Totally normal in a ladder test right...?

Here is the problem, I loaded up some 10 shot groups of N540 at 24.6gr hoping to get a 600 yard load and 23.7gr of Varget (added .2 gr) hoping to get a little more than 2600 FPS. I first fired a 5 shot control group of 77 gr OTM AAC factory ammo (fly's at about 2815 out of my rifle; it's good stuff!). Everything seemed to have followed the trend of pressure signs. Pancaking is especially more prevalent. Here are a few pics: View attachment 596975View attachment 596976View attachment 596977

I'm shooting a Bartlein Barrel that was manufactured at a time know for premature barrel extension wear out. Could these signs be a sign of that? The 23.7 gr load of Varget shot .863 MOA @ 100 and the function was fine. I've never shot a barrel out but I got the upper from a good friend and have put about 700 rounds through it.

Is my barrel that picky? I wouldn't expect such a drastic pressure sign jump with .2 gr of varget. I will be monitoring the 23.5gr load of Varget at my next practice. Maybe I'm over thinking this and need to just dumb down my loads but it really doesn't feel like I'm reaching for any extreme's. Perhaps I need to be humbled.

Any words of wisdom would be greatly appreciated. Thank you for your time.

Ryan

I have shot more than a few barrels out, but the signs of a shot out barrel have always been groups opening up. A group of .863 does not indicate the barrel being shot out. All barrels are picky about ammo, some more-so than others, even 1 gr of powder can make a difference. As for over pressure, again even 1 gr of powder can make the difference between being at max pressure or being over pressure. NEVER ignore the signs of over pressure. As mentioned by another, a carbon ring can pinch the case causing the bullet to have to remain in the chamber until sufficient pressure is built up to push it out and down the barrel. This can cause over pressure to show up on the fired cases. A carbon ring often shows up if the barrel only receives a cursory cleaning, running the brush down the barrel a few times without letting the solvent soak inside the barrel for any period of time.

To remove a carbon ring you will need to soak the chamber/barrel in a good powder solvent like Hoppes (CLP will not do the trick) or some other solvent, not multi use cleaning agents, most are not aggressive enough to tackle a carbon ring.

Soak the barrel, especially around the chamber with said solvent and let it sit for at least 10 to 15 minutes. Place a bronze (not steel) brush on the end of a multi section cleaning rod, chuck the rod into a variable speed drill and at a relatively low speed run the brush into the chamber and throat for 15 to 30 seconds. Clean the entire barrel thoroughly then soak it again and repeat until the carbon ring is removed. If you have a bore scope you will be able to see the progress, without a bore scope do the cleaning process at least 3 times then take the rifle to the range and check to see if your pressure problem has disappeared. Once the ring is gone, clean the rifle at least every 200 rounds letting the solvent soak for at least 10 minutes before brushing, then run the brush through the barrel at least 10 times. My experience is the soaking and 10 strokes of the cleaning brush will remove/prevent the buildup of a carbon ring. Before you ask, No, the bronze brush will not harm the chamber or rifling when using the drill. Bronze is much softer than the barrel steel. As a word of extreme caution DO NOT USE A STEEL BRUSH ON THE DRILL AS IT WILL DAMAGE THE CHAMBER AND BARREL.

Good Luck and Good Shooting.

 

[Toddxusmc]

One final observation... below is a pic of a round I chambered (left) and a round that has not been chambered (right). Every round that I chamber has some light scuffs approximately at the ogive all the way around the bullet diameter (pointing at the line with the tipped bullet in pic). I have read this is a sign of carbon ring build up. So its starting to sound like I do in fact have the ring. It looks worse in person, best I can do for a pic.



View attachment 597197

Besides everything that's been covered:
You could be jamming the rifling a bit. Competeting a long time ago-before Stoney Point came on the scene we'd use marker and adjust the seating depth until the marker wasn't scratched off. If with the 77gr SMK At COL 2.245-2.250 you have those markings it could indicate your chamber has a short leade, likely shorter than spec.. If that's indeed the case w the 77 SMK back off the powder and seat appropriately or have a smith extended the leade to proper spec. Match rifles tend to have chambers that are on the minimum side of specification standards so these problems aren't uncommon. Using a Stoney Point/Hornady comparator to determine CBTO measurements and leade measurements would help you in determining things.
As to your loads, the best way to determine max is using case head measurements. If lets say the average expansion on factory loads averaged .380 at the head; when your loads hit that measurement at the head of the brass you are at the maximum for your rifle and it really would be unwise to go higher. This method is irrespective of components, powders primers etc. It relies solely on the pressure exerted on the brass. A blade micrometer will give you best accuracy with this method.
Looking at primers is the least reliable way to try and figure out if you're at max, primer cups among all other things have min/max tolerances, a lot# that had cups made to the thinner side of acceptable spec will give different indications than the lot#s that favor the thicker side of the spec…combine that with min/max diameters to flash holes and the fact you're using brass from unknown lots and you have a lot of variable stacking. With military brass about the best you can do is use brass from the same year, then weigh sort them.
It IS all about details dimensions and physics.
Lastly, if you're shooting the warmer months id give AA2520 a try and look up the NATO loads in the Western Powder manual. It will give you top velocity with 75/77gr. The downside is it's temp sensitive.
The 8208 is a great powder but it is difficult to find and quite expensive.
Regards,

 

[grizlywinkleman]

I have not experimented with finding the lands. It is on my radar for my single feed stages of firing but I will prioritize that to see if my throat is indeed shallow. I will also start seperating my brass by year and weight as well. I have plenty of it. I will also put a few 10 shot groups together with CCI No.41 primers. Those are the only other SR primers I have at the moment. Got a primer pocket go/no go gauge on the way as well.

My barrel is 223 Wylde chamber. The reason I brought up neck turning is because it yields consistent neck tensions regardless of sizing method (so I read). I do not anneal. What is an affordable entry level set up I could look into?

I'll look into Zedickers book as well.