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Reduced loads for barrel break in....??

6BR Question.....

Is there any benefit to reducing loads for barrel break in besides saving some powder? Being that you are just breaking in the barrel you wouldn't necessarily need tack driving accuracy, huge amounts of speed, or high pressure.

An example: 87gr. Vmax over 31 grains Varget @ 3100+ fps, a favorite load listed in the reloading area of homepage. Do you really need this hot of a load for break in? Would 26-27-28 grains do the job also?

Just a subject that came up at work and had me thinkin'....

Brian
 
Brian,
You need to run pressure test on the new barrel to find out what your max loads are, might as well do it when you are doing your one shot an clean barrel break in thing...

Chuck
 
Bric,

If you use new brass at reduced loads to break in a barrel that brass will not ever be suitable for high pressure loads! It will only be suitable from then on for low pressure loads. That brass at high pressure will be prone to failure. Conversely if you use a higher pressure load on the first firing of new brass you can then use it for low, moderate, or full pressure loads with no ill effects.
I measure my new brass at the web, and try to keep case growth due to pressure below .001 on the first loading. Upon the second firing an additional .0005 is acceptable. I don't ever want to see expansion beyond .0015 ever, regardless of number of loadings on that particular batch of brass. If I do, the loads to hot, and I reduce it .5 grains. That way it should be safe over the range of temperatures that I shoot in.
In my opinion case web expansion is the only reliable means of judging pressure. The primers can still look fine and the case web expansion may be .003! Don't trust how a primer looks, it will lie to you every time.

But back to your original question, this is why you want to break in the barrel with a SAFE,I repeat SAFE, higher pressure load.
Danny
 
Danny,

I had no idea that the web would expand that much except with very high pressure loads. The tip about shooting the brass at low press use and it not being acceptable for max pressure is also very interesting. Thanks for the information.

Chuck
 
You might as well shoot for groups while breaking in a barrel,if you believe that process is important). Some of the best groups I've shot from my gun were done with Virgin brass during break-in.

Regarding low vs. high pressure during first firing, I have no data one way or another on Danny's theory. Many people think you need a couple of strong-charge firings to get a crisp shoulder and "seasoned" brass. I've shot plenty of factory loaded ammo, which is about a 57,000 psi load, and that brass works very well thereafter.
 
Barrel break-in is a fraud. Go here and read

http://www.6mmbr.com/GailMcMbreakin.html

Every round you fire should have a purpose and barrel break-in is not one of them.
 
Thanks for the replies guys!

Using the example I refered to in my original post, 31grns. Varget over 87 gr. Vmax @ 3100fps. Rule of thumb is to start at a reduced loading and work your way up to that pet load to make sure your barrel is capable of handling those pressures etc.

So lets say starting load will be 31grns. Varget minus 10%, giving us 27.9grns as our starting load.,Some people use 15% as their reduction percentage.) We would work our way up from there towards the 31grns in the pet load. 3 grains of powder is not a huge amount but enough to make a noticable difference in the 2 loads. I guess my question should have read 'How reduced is too much?' I wasn't referring to just having enough pressure to force the bullet out the muzzle.

I am in somewhat of an agreement on Gail McM's break in thoughts. I use my own modified procedure. I also don't use JB paste on a barrel unless I am stripping moly from it to re-treat the bore, and even then very sparingly. There are a whole slew of products out there now that will remove copper like a champ. I use Sweets, 50BMG, Kroil, and Shooters Choice. I haven't found anything that could get passed the 50BMG, that stuff is hardcore.

Anyway, thanks again for your thoughts guys!

Brian
 
i would take the advice of the guy that said each lot or group is worth shooting like it was the load that you have been shooting all along
 

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