Muzzle Break causing feeing issues? Update

rockchalk06

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Unless you’re shooting PRS I’ve found the temp issue to be over emphasized for many powders, TAC included. It’s there, keep it in mind and drive on. You most likely find a MOA load if not better. If you don’t like it, I’d probably take it off your hands.
Thanks. I was running low on 4064, so I went ahead and bought a 8# jug of Tac. Also grabbed a box of 77 grain Barnes bullets too. My Bergers are sold out.
 

rockchalk06

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Cabela's in Allen had a buttload of TAC and Varget, and 8208 and a few AA powders, and Gunmaster had a bunch of Varget and 4895 plus about 30 bottles of H4350 and some 8 pounders.

Cabelas or BPS might have the same since they all order the same

I don't think I'd spend $$ on VV powders. They're kind of unimpressive to me. But that's me.
I've had really good results with the pistol stuff over the years. Very clean too. I was hoping the same would be true on rifle. I have a bunch of N135 left too. I have a killer 62 grain FMJBT load for my 16" carbine that I can use it for.
 

JEVapa

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Thanks. I was running low on 4064, so I went ahead and bought a 8# jug of Tac. Also grabbed a box of 77 grain Barnes bullets too. My Bergers are sold out.
Don't hesitate to get 77gr SMKs; they're always on the shelf. It's the base bullet for MK262. Since the powders are blended for it, it's hard to get it going that fast without pressure signs or accuracy loss...and they like a crimp. TAC and 8208XBR are a couple you can get there. It'd be the same with the Bergers.
 

rockchalk06

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Another option might be to install a JP Rifles Silent Captured spring unit. You can tune your buffer weight and the spring weight. Might let you run the muzzle break and your load of choice. JP Rifles
I have actually been looking at that and possibility running an adjustable gas block if loading these hotter doesn't provide decent accuracy. The reason my load is so light was the SD and group it produced. When I got closer to max with N133, groups opened up past an inch and SD's went as high as 40. My current load was just shy of 1/2" and 7.6 SD.
 

rockchalk06

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The data for that powder and Berger 77gr are only on the VV sight. The mins are really slow. I'd pull them down and use a different charge or powder that should put them in the 2600-2750 fps space. That bullet is made to go fast. Attached is a pdf from Load Data
@JEVapa

Do you know the specs of this data by chance? Twist, Barrel Length, Temp?

These were my findings:
21.5
1668968689793.png

21.7
1668968722813.png

22.0
1668968745461.png

22.3
1668968762265.png

Screenshot_20221120_122331_Chronograph.jpg

This was the best group and just over an inch for 5 shots. I was impressed with it, but no clue what happened to my chrono. Same location of chrono, same location of rifle, no wind, chrono light on the entire time, but I'd assume this is 2458 FPS.

No pressure signs on the brass at all. I think I will work up a tad more and see what kind of velocity I can get and groups. I just wish that last SD was better. 25 isn't the end of the world, but I can do better.

I left the ammo in the bed of my truck over night and went from the bed to the rifle, so it was cold. Great thing about shooting in 31 degree weather, barrel stays pretty good.
 
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rockchalk06

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Also, I'm calling my issue fixed!

Prior to each 5 shot group, I fired one round of M855 to warm my barrel. Bolt locked backed on empty mag. 5 test loads inserted, all 5 fired with zero issues and bolt locked back on the empty mag. Did this will 3 different mags I brought.

I appreciate everyones help. If anyone knows a member here who would like a years subscription to the forum, let me know. I want to pay it forward for the help I received.

Thanks OSA
 

Bocephus123

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Also, I'm calling my issue fixed!

Prior to each 5 shot group, I fired one round of M855 to warm my barrel. Bolt locked backed on empty mag. 5 test loads inserted, all 5 fired with zero issues and bolt locked back on the empty mag. Did this will 3 different mags I brought.

I appreciate everyones help. If anyone knows a member here who would like a years subscription to the forum, let me know. I want to pay it forward for the help I received.

Thanks OSA
nice to help people when we can! ( i had no input on this subject )
 

JEVapa

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@JEVapa

Do you know the specs of this data by chance? Twist, Barrel Length, Temp?
Are you talking about the pdf I attached? If so, no, other than the info they give at the top. 👇 👇

Notes: Case trim length: 1.750; COAL: 2.260"; barrel length: 24"; NOTE: An 80.5 grain Berger Match Fullbore Target bullet can also be used for the 80 grain data. WARNING - Approach maximum loads with caution. (Berger Bullets Reloading Manual 1st Edition)

This is probably a 1-9 or 1-8 max.

Looking at your groups...it looks like you are using an electronic scale that's cold...or you're using a throw bar, or both. Just an assumption because your SD and ES should be way smaller...those are Lake City kind of spreads.
My scale will get all squirrely like that so I have to cal it often or bring it in the house.

Another thing is that your chrono looks like it's about to S**t the bed, or it doesn't like the cold. See if you can get a hold of a labadar, magnetospeed, or an Oehler to confirm. None of those speeds match up with the charges you have listed.
Don't forget a crimp

This is off Hodgdon for 77 gr SMK:

Ramshot TAC 0.224" 2.260" 21.1 2,483 49,100 PSI 23.4 2,759 54,500 PSI
 

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