Muzzle brake woes and copper projectiles

[skipglo]

I've chased my tail for too long. the very first round i tried in my 7mm was a 160gr factory accubond. it shot .2-.34 groups at 100yd. i would have stopped there but i wanted an all copper projectile for hunting. the 139lrx shot an occasional .75 group but wasn't consistent and the 160tsx/168vdl had 2-5" groups at 200yd. the groups opening up seem to be the result of adding a new muzzle brake (jp tank). the factory brake from fierce grouped better and was much lighter weight. after adding the heavier jp tank i was able to shoot a 6" 3 shot at 700 with the lrx, which showed promise. the next time out, the bullets were flying. after trouble shooting scope, mounts, barrel contact, action screws, myself, etc. i went back to the accubond and the factory muzzle brake. it shot a .33" group. i threw on the jp tank and the group opened up to about 2". the first shot was always a flyer with this brake as a cold bore shot. full disclosure, i did bore out the brake to comfortably shoot at 30 cal and sanded down any burrs. i still believe the weight may have affected the harmonics. it's a shame because i had no issue spotting hits at 100 yards with this brake. my factory radial has a bit of flip and plenty of dust blow up to prevent spotting hits.

so, now i'm back to the decision of shooting the accubonds or selling the gun and finding something to shoot a copper bullet. how much lead do accubonds really shed when shooting lungs? my small sample size of 1 cow with an accubond was a double lung pass though with no blood trail.

If you want to try a break I will send you one. You like it, I will discount the price to 80.00 U.S. If you don't send it back. They are a new 2 piece set..the shroud Re-directs the sound.

 

[skipglo]

P.S. comes with the crush washer and jam nut!

 

[skipglo]

I've chased my tail for too long. the very first round i tried in my 7mm was a 160gr factory accubond. it shot .2-.34 groups at 100yd. i would have stopped there but i wanted an all copper projectile for hunting. the 139lrx shot an occasional .75 group but wasn't consistent and the 160tsx/168vdl had 2-5" groups at 200yd. the groups opening up seem to be the result of adding a new muzzle brake (jp tank). the factory brake from fierce grouped better and was much lighter weight. after adding the heavier jp tank i was able to shoot a 6" 3 shot at 700 with the lrx, which showed promise. the next time out, the bullets were flying. after trouble shooting scope, mounts, barrel contact, action screws, myself, etc. i went back to the accubond and the factory muzzle brake. it shot a .33" group. i threw on the jp tank and the group opened up to about 2". the first shot was always a flyer with this brake as a cold bore shot. full disclosure, i did bore out the brake to comfortably shoot at 30 cal and sanded down any burrs. i still believe the weight may have affected the harmonics. it's a shame because i had no issue spotting hits at 100 yards with this brake. my factory radial has a bit of flip and plenty of dust blow up to prevent spotting hits.

so, now i'm back to the decision of shooting the accubonds or selling the gun and finding something to shoot a copper bullet. how much lead do accubonds really shed when shooting lungs? my small sample size of 1 cow with an accubond was a double lung pass though with no blood trail.

One more thing....is your scope base a one piece base...20 moa?

 

[Snowbird]

skipglo,

i like the idea behind redirecting the sound away from the shooter. how much does the brake weight? 5/8x24 or 1/2x28? i'm running the latter but can get an adapter.

and yes, the scope base is a 20moa one piece.

 

[skipglo]

skipglo,

i like the idea behind redirecting the sound away from the shooter. how much does the brake weight? 5/8x24 or 1/2x28? i'm running the latter but can get an adapter.

and yes, the scope base is a 20moa one piece.

5/8 x 24tpi .. 30 cal.pull your base and put a level on it...side to side not length ways... I had a very similar situation to what you are describing...to long of a story. Cost me 6 G's...three new Scopes...nope the base...see below and not the muzzle break either. Theses are great brakes. I regularly sell them for 185.00

 

[skipglo]

P.S. I will weigh one in the morning and get back to you!

 

[NotAMillennial]

I have a Fierce 7mm as well with fascinatingly similar results. The gun CANNOT shoot factory 160AB or 175LRAB in a group bigger than 0.6", usually 0.4".

DO NOT try any other bullets with that rifle. I am close to 600 rounds of load development deep on my rifle and ended up saying F it and loading 160 AB's at 2945 FPS because it cannot fail. I too wanted solids to shoot in the rifle.

A list of the bullets I tried EXTENSIVELY to make shoot:

145 LRX
168 LRX
160 Partition
175 Partition
175 ELDX
143 (or was it 140?) gr hammer hunter

Powders: RL 23, H4831, Retumbo, H1000

Again, I cannot test a powder or seating depth with the 160AB or 175 ABLR that shoots much over 1" with that rifle, and anything else has been no better than 0.5", and those with horrible SD/ES that I couldn't keep.

I re bedded the thing to be safe as well with no change.

If anyone else has theories on this I'm all ears (perhaps bore diameter??).

I gave in and am rolling with the 160 AB using RL 23 @ 2945 fps, a large jump to lands, and federal 215m primers. I suggest you do the same before throwing money supplies and time away.

 

[J E Custom]

My suggestion would be to replace the existing brake and have a new one installed properly on a Lathe as mentioned.

I have never seen a muzzle brake hurt accuracy when installed correctly, But have seen many bad installations wreck accuracy.
They must be installed perfectly concentric to the bore and have minimum clearance to the bullet. I recommend .015 to .020 to get the most effect from the brake. More clearance only reduces the recoil reduction more.

Brakes should be installed without any crush washers if possible and should be timed and shouldered against the barrel shoulder for the best/most accurate concentricity.

Also, barrels are individuals and sometime prefer one or two bullets, so changing to something else is often counter productive. The bonded core Accubonds will perform well on game and are normally very accurate if the barrel likes them.

Replace the brake and stay with the Accubonds would be my advice.

J E CUSTOM

 

[Snowbird]

I have a Fierce 7mm as well with fascinatingly similar results. The gun CANNOT shoot factory 160AB or 175LRAB in a group bigger than 0.6", usually 0.4".

DO NOT try any other bullets with that rifle. I am close to 600 rounds of load development deep on my rifle and ended up saying F it and loading 160 AB's at 2945 FPS because it cannot fail. I too wanted solids to shoot in the rifle.

A list of the bullets I tried EXTENSIVELY to make shoot:

145 LRX
168 LRX
160 Partition
175 Partition
175 ELDX
143 (or was it 140?) gr hammer hunter

Powders: RL 23, H4831, Retumbo, H1000

Again, I cannot test a powder or seating depth with the 160AB or 175 ABLR that shoots much over 1" with that rifle, and anything else has been no better than 0.5", and those with horrible SD/ES that I couldn't keep.

I re bedded the thing to be safe as well with no change.

If anyone else has theories on this I'm all ears (perhaps bore diameter??).

I gave in and am rolling with the 160 AB using RL 23 @ 2945 fps, a large jump to lands, and federal 215m primers. I suggest you do the same before throwing money supplies and time away.

I agree it seems the gun wants what it wants. I found very high ES & SD on my factory AB rounds too. It's why I initially discounted them and started looking elsewhere for a factory longer range round. I'm going to put on skipglo's brake and see how it goes. I may end up hunting with the Tikka this year for my cow hunt and take the savage 6.5 cm for antelope. That gun seems in capable of larger groups than a half moa out to a thousand. It regularly shoot 2" groups at 700 but it is my heaviest gun.

Good time to take the great advice I got in this thread and shoot what works in each gun. Thanks for all the replies.