.308 Muzzle Break

I'm not familiar with VMR 4350 powder but from what I see with other powders, thats a pretty light load. IDK, like I said, not familiar with this powder.
 
Is the VMR-4350 a typo. I know IMR-4350 is pretty well known.
If its a typo and you are actually using IMR-4350, try switching to IMR-4895 or IMR-4064.
Those two are great for 308 Winchester
Again, if its supposed to be IMR-4350, thats a pretty slow burning powder for 308 especially with light weight bullets.
Just a suggestion.
 
Originally Posted By: wyshadowWas able to make it out to the range today. I shot the gun over the chronograph about 8 times but the chrony only read 5 of the shots. I was very disappointed by the numbers and shooting at a 100 yards, the gun couldn't group at all. Chrony numbers are 2564, 2588, 2534, 2478, and 2520. Average - 2536 ES - 110 SD - 42 and these numbers showed in the groups. Was getting a flyer out of every 4th shot and made for a frustrating day.
I tried to take off the break at the range but I couldn't do it. Came back to the house and put the gun in the vise. I was able to remove the break. Will try going back to the range this tuesday.

With you losing velocity AND accuracy, I am wondering if the bullet might be striking the brake. I too have installed a LOT of muzzle brakes without ever seeing a loss in velocity or accuracy. Are brakes necessary? Absolutely not. Can they make follow up shots faster? Yes then can. But I have not ever seen what you are seeing on any brake I have installed. I have seen similar problems with suppressors suffering from baffle strikes which can happen because the threads and the muzzle centerline are not parallel but I have not seen that with a short muzzle brake. Keep us posted.
 
Ya, the IMR 4350 is not going to be ideal for the 308. You are going to see low velocity and inconsistent results like you are getting. Like the others have said, IMR 4064, 4895 (IMR or H) will work. IMR 3031, Varget, or IMR 8208 XBR would also work for both. Not sure if you have any other powder on hand.


Curious, where did you find data for IMR4350, as I can't find any readily available? There is usually good reason for this.
 
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Before substituting one powder for another, you should be real sure they will interchange before you end up making a bomb and ruin a good rifle and get yourself hurt. Alot of times powder burn rates are very similar to each other but I don't trust myself to use powders not listed for certain calibers. Others with more experience do it but I don't feel like I have the knowledge to do it. Just saying be careful with your loads.
 
I've put about thousand rounds through my gun using this powder and have great results. I've loaded rounds to max charged and didn't get any pressure signs on the cases.
Lefty SRH, I will try IMR-4064. I've got about 1/2 pound left and will try a different powder.
 
Originally Posted By: wyshadowI've put about thousand rounds through my gun using this powder and have great results. I've loaded rounds to max charged and didn't get any pressure signs on the cases.
Lefty SRH, I will try IMR-4064. I've got about 1/2 pound left and will try a different powder.

What is the data you are referencing?
 
Originally Posted By: erikc838Originally Posted By: wyshadowI've put about thousand rounds through my gun using this powder and have great results. I've loaded rounds to max charged and didn't get any pressure signs on the cases.
Lefty SRH, I will try IMR-4064. I've got about 1/2 pound left and will try a different powder.

What is the data you are referencing?

IMR - 4320
 
Just got back from the range. was able to shoot the gun without the break over the chrony and this what I got with the 130 grain speer HP bullets. 2564, 2554, 2574, 2544, 2578, HI-2578, LO-2544, AV-2562, ES-34, SD-14 and this load was producing groups under an inch at a hundred yards. So, my $35.00 shipped muzzle break is the problem. If I had to guess, maybe the vents are not machine at the same angle on both sides of the break. I don't know but there is something up with the break
 
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One of the main issues with the muzzle brake, is that it is made for a .338 and not specifically for a .308, so your exit pupil is way oversize!

A muzzle brake for any .30 caliber barrel should have an exit pupil no larger than .338 or .030 over bullet diameter. When I make muzzle brakes for a .30 caliber or any caliber as far as that goes, I cut the exit pupil .014 over bullet diameter, which allows .007 per side clearance, which is as they should be...
 

harrel's precision is a very well known muzzle brake fabricator and probably really has made thousands of brakes. he says "All brakes must be bored .020" over bullet diameter and installed by a gunsmith"
other informational sources seem to all recommend around .020 clearance as a minimum.

https://www.longrangehunting.com/threads/muzzle-brake-bullet-clearance.56805/

http://forum.accurateshooter.com/threads/how-much-clearance-between-bullet-and-brake.3864952/

https://www.practicalmachinist.com/vb/gunsmithing/clearance-muzzle-breaks-310355/
 
Originally Posted By: wyshadowJust got back from the range. was able to shoot the gun without the break over the chrony and this what I got with the 130 grain speer HP bullets. 2564, 2554, 2574, 2544, 2578, HI-2578, LO-2544, AV-2562, ES-34, SD-14 and this load was producing groups under an inch at a hundred yards. So, my $35.00 shipped muzzle break is the problem. If I had to guess, maybe the vents are not machine at the same angle on both sides of the break. I don't know but there is something up with the break

That's one of the fundamentals of troubleshooting, go back to a known good point and see if we can replicate the proper behaviors, then install our variable and see if the variable is causing the issue. Sure feels good to find the problem.
 
Mr. Harrell will also tell you that if a barrel is turned between centers, and the headstock and tailstock are in proper alignment, you can actually go as tight as .007 over bullet diameter!

The .020 and .040 clearance that nearly all muzzle brake manufacturers insist on, is to keep the bullet from striking the inside of the muzzle brake or the exit pupil. But IF everything is machined properly and on centers, tolerances can be held much tighter!
 
Originally Posted By: 1ASSASSINMr. Harrell will also tell you that if a barrel is turned between centers, and the headstock and tailstock are in proper alignment, you can actually go as tight as .007 over bullet diameter!



please show me where he says that.
 
I had a gunsmith thread the break onto the barrel. The gunsmith did warn me the break was meant for a 338 cal but I decided to try it
 


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