Pressure Signs - M16 High Power Rifle

[Chris F]

When you start playing with OALs to the lands here's some numbers to bear in mind that most service rifle shooters will understand;
A Sierra 80 (old style) will touch lands at around;
2.460 in a Wylde;
2.440 in a CLE
2.550 in a NATO
Under 2.400 in the 223 match that Krieger was using.
Using a different bullet will give you different numbers. John at White Oak changes out his reamers regularly…but if a smith doesn't, reamer wear will give you a shorter measurement than above.

 

[jeb405]

Toddexusmc did a much better job in his explanation related to distance to rifling than I did, I was trying to say the same. The following video has an interesting option to find lands without tools, first I have heard of this one and I am old.

From Ultimate Reloader, Three Ways to Find the Lands!

 

[Citified]

When I had a barrel made for my match ar15, I had it short throated so there would not be a big jump to the lands with 77 grain bullets.
I will never shoot 80s in this rifle because of mag length requirements.

 

[grizlywinkleman]

Toddexusmc did a much better job in his explanation related to distance to rifling than I did, I was trying to say the same. The following video has an interesting option to find lands without tools, first I have heard of this one and I am old.

From Ultimate Reloader, Three Ways to Find the Lands!

This is the video I actually learned from to do on a few other rifles. I prefer the loctite method. I just thought the mag length was more important than the lands jump.

 

[Chris F]

I tried nationalmatch.us board in the past and didn't get any responses. I thought it was a dead forum.

I just got on there after a bit of a hiatus. I can assure you it's still pretty active. In fact I slid down the rabbit hole catching up on discussions I had missed. Some of the more interesting ones were "cam pin wear; problem or no", and how good offhand shooters approach their hold. Ron Zerr posts as r_zerr and he always has good insights.

I'll share a story for the folks that are sorting and weighing LC brass. When I switched over to the AR Service Rifle, I didn't have loads of time to work up loads. I spent the time working up a 600 yard load (24.0 gr Varget which caused marks on my cam pin right away) and I went with Black Hills Remanufactured 68 gr Hornady (this was the pre-77 days). If you've been around long enough you've seen the BH Blue Box ammo. It was x-ring accurate and even after I started reloading short line ammo, I had no problem grabbing blue box if I was short on loading time. That stuff was loaded with mix-master brass. Not only was it multiple years of LC, but also WCC, Win and Fed. I might have even won a leg or two with Blue Box.

Another story. In my early AR days, I was discussing short line bullets with a friend who shot for the USAR Team, Al Ewing. Al told me he was asked to T&E a new bullet from Sierra not yet available to us mortals. He said it weighed 77 grs and shot well out of the magazine. In fact he said it didn't care how far it had to jump to the lands. We were talking about throat configurations and his advice was, if this bullet made it to market, it wouldn't matter what chamber I chose. He was right. That was probably 25 years ago and I'm still shooting 77's. RIP Al!

 

[bamban]

I just got on there after a bit of a hiatus. I can assure you it's still pretty active. In fact I slid down the rabbit hole catching up on discussions I had missed. Some of the more interesting ones were "cam pin wear; problem or no", and how good offhand shooters approach their hold. Ron Zerr posts as r_zerr and he always has good insights.

I'll share a story for the folks that are sorting and weighing LC brass. When I switched over to the AR Service Rifle, I didn't have loads of time to work up loads. I spent the time working up a 600 yard load (24.0 gr Varget which caused marks on my cam pin right away) and I went with Black Hills Remanufactured 68 gr Hornady (this was the pre-77 days). If you've been around long enough you've seen the BH Blue Box ammo. It was x-ring accurate and even after I started reloading short line ammo, I had no problem grabbing blue box if I was short on loading time. That stuff was loaded with mix-master brass. Not only was it multiple years of LC, but also WCC, Win and Fed. I might have even won a leg or two with Blue Box.

Another story. In my early AR days, I was discussing short line bullets with a friend who shot for the USAR Team, Al Ewing. Al told me he was asked to T&E a new bullet from Sierra not yet available to us mortals. He said it weighed 77 grs and shot well out of the magazine. In fact he said it didn't care how far it had to jump to the lands. We were talking about throat configurations and his advice was, if this bullet made it to market, it wouldn't matter what chamber I chose. He was right. That was probably 25 years ago and I'm still shooting 77's. RIP Al!

Chris, thank you for bringing up the BH offerings into service rifle community. Another company supported our TX team with manufactured ammo when they first started - HSM. That was before the 77s. We bought our short line and NTIT ammo from them loaded with 69s. We must have bought north of 50K from them at a bargain price lower than what we load for. Then they got big.

 

[grizlywinkleman]

Teslong borescope came in today. I'm not a borescope aficionado but I am very impressed with it for the price! I do believe I have a carbon ring. Here are the pics in order and with description...


PIC 1: Shoulder location of chamber


PIC 2: Case neck location of chamber


PIC 3: End of case neck/throat and perceived carbon ring


PIC 4: Throat


PIC 5: Lands


The two below pics are of the perceived carbon ring:



The three below pics are the carbon ring with a fired piece of brass fully seated in the chamber for reference:

Your expertise in confirming (or denying) this is appreciated. I'll wait to get the scrubbing on this spot until then.

Ryan

 

[Chris F]

Chris, thank you for bringing up the BH offerings into service rifle community. Another company supported our TX team with manufactured ammo when they first started - HSM. That was before the 77s. We bought our short line and NTIT ammo from them loaded with 69s. We must have bought north of 50K from them at a bargain price lower than what we load for. Then they got big.

I remember those! little orange boxes of X's! Jeff had the Ditch guy bring a case when he came to visit. I think the TSRA Team spec'd 69 Molys on top of Varget. Worked out great since at that point I was shooting Varget at 600.

 

[Citified]

Little carbon ring. That is not the cause of your issue though.

 

[Chris F]

That's more like normal flame wear. A carbon ring would be a black shiny buildup almost like glass or ceramic. I believe that black ring I see in the later pics is just a shadow of the neck/throat junction. It's not present in the oic without the case.

Hit your throat with some JB if that black stuff bothers you. Iosso if you "really" think you got a carbon ring.

 

[grizlywinkleman]

Thanks. I will remove it just to eliminate it as the culprit.

 

[Citified]

I think you are down to switching to a thicker primer.

 

[grizlywinkleman]

Switch to CCI 450 or 41. Another option is the Federal 205MAR.

Bamban hit the nail on the head! Threw some 5 shot groups together with all my loads I had worked up and CCI 41 primers and had minimal flattening issues. Even had a kinda loose primer pocket (top left in pic) and still looks good.

Basically ending up sticking to my Varget load with .2 gr added. Had the best SD, ES and grouping. Might not be a great velocity bump but it is the most consistent. I will start separating my brass by year and weight though. See if I can bring those numbers down o. The other powders.

Thanks a bunch to you all! I learned alot and continue to get more polished with my reloading.

 

[Chris F]

Looks like you are on a good path now. I also saw that you found your way back to NationalMatch and are getting good insights on mixed lots of brass.
If I could give you a thought to close out...Highpower is not benchrest and the AR is inherently accurate. With a 2moa 10 ring, 1 moa x-ring it shouldn't be hard to find a load that will clean a target. Now that you're almost there...the real work starts; working on positions, wind reading and the many human factors that put you in the X-ring out of position. Good luck!