Muzzle Break question

[Ultramag45]

I have a 338 RUM ..I have chronographed it a few times at 3150- 3170fps with 93 gr.. of RL22 a 225 ACCUBOND...when I did this It was a stock barrel.... I know have a muzzlebreak on it, and just thought it wouldnt make any difference, as far as velocity I shot prob 200 rounds through it.... shot today , and checked it just for fun, and was 100 fps slower... Same conditions same batch of powder, clean rifle, would a muzzlebreak make you lose that much of velocity,,,, any help on this would be a plus, thanks guysgun)

 

[Rimfire]

When you first checked it on the crony was it much hotter out? I have seen a 100 fps spread with R-22 from a hot day to a cold day.

 

[J E Custom]

I have a 338 RUM ..I have chronographed it a few times at 3150- 3170fps with 93 gr.. of RL22 a 225 ACCUBOND...when I did this It was a stock barrel.... I know have a muzzlebreak on it, and just thought it wouldnt make any difference, as far as velocity I shot prob 200 rounds through it.... shot today , and checked it just for fun, and was 100 fps slower... Same conditions same batch of powder, clean rifle, would a muzzlebreak make you lose that much of velocity,,,, any help on this would be a plus, thanks guysgun)

The next time you go to the range shoot 3 to 5 rounds through the chronograph with the
break then remove it and repeat the process .

clean the barrel and reverse the order of the test and this should settle the question at
least with your rifle and load combination.

Make sure the barrel cools between each test.

J E CUSTOM

 

[Long Time Long Ranger]

Two great replies. I think it should get more velocity though with that bullet. I did a lot of work through the years with the 338-300 ultramag which is essentially the same thing and they will get over 3300 fps with the 225 AB. Just a tad more powder but shouldn't effect it that much. My 340 wby will shoot them over 3200 fps with a 28" Douglas supreme air gauge barrel made back in the 70's. Try some other powders.

 

[Ultramag45]

OK, It sure is strange that the gun shot 3150 +fps without the break and now all of a sudden a 100 fps+ difference... with a break on it.... I cant remove my break , and would a different can of powder make that much difference.... I had shot a couple hundred rounds through it with the break on it , long after I installed the break, figuring it wouldnt make a difference..... so it has been a couple years since I chronongraphed my gun, What else could there be!!!!!!! the accuracy hasnt changed at all.... I know every gun is different, but if you were to folow the book, I am already 2 grains over max... and was barely at their fps...... now I am 100 fps slower then the book..

 

[Franklin]

What style brake? If you had the barrel ported, then this would explain the decrease in velocity.

 

[Ultramag45]

Nope barrel isnt ported, Had Wayne york of Oregunsmithing intsall one of his....also, possibily throat erosion.... How would one eliminate that.... Asked Shawn and that is what he came up with...... thanks guys