Light barrells

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Ive got an old M77 in 7mm mag and havent found the "magic load" for it as of yet. The barrell seems to heat up pretty fast and gives me a pattern instead of a group. Ive only tried the slower powders so far....IMR4831, RE22,H1000, RE25, and some H870 I had around. Also different primers...CCI250,WLRM,and F215s. Ill typically get two rounds near 1 moa, and the rest is scattered about like a mad mans ka ka. Does anyone think that faster powders from the light sporter barrel would do any better. My preference is for a 160g bullet, but what ever works best right! Ive changed my way of thinking in the past that faster hotter is better. Accuracy is key.
Also I havent tried regular large rifle primers in any loads. Anouther thing I havent tried is to shoot a group letting the barrell cool between shots. I made up a little fan thingy with a small 12v fan from PAuto and some flex tube, plug it int the cig lighter....works pretty good.
anyway .
thanks bruce
 
Light hunting barrels will heat up quickly no matter what powder. Allow cooling time. It's essential. Especially for a light hunting barrel.
You don't need magnum primers just because the cartridge is called a magnum. Magnum primers are about the powder used. They have nothing to do with the cartridge.
 
I'd say at least a minute between shots. For my 300WM, with a skinny barrel, I wait at least a minute, before I even approach the gun to take another shot, so taking my time, it usually ends up being 90-120 seconds between shots. Then I wait at least 5-6 minutes before shooting the next group. It gets warm, but never hot. Run your little fan, keep the bolt open between shots, take your time. At the end of the day, practice quick follow up shots, but when you're working on accuracy, no sense rushing, especially for load testing. If you're trying to make a hunting load, just remember, that hunting shots are almost exclusively taken from a cold barrel.
 
Yesterday I shot my best group so far from my skinny barreled 7x57 by using the Lee factory crimp die. 5/8"
With no crimp it was hard to beat 1".
Uniform neck tension is important, both of these I think especially so because the barrel is so long-throated that I cannot seat the bullet close to the lands; this is also important for accuracy.

I use H4350, but suspect that powder selection is not so important.
 
had that same problem in a M77 7mm Mag :eek: :D well look at that :D

anyways it would never shoot a group first 2 shots would be fine but then it would start wandering around, made me very angry. I gave up on it and bought another rifle. (and then a few more :D ) Then I did some research and it seems that the beddin is the problem, has a preasure point at the tip of the stock that should be removed if your going to bed it. I bought a synthetic stock for mine but have not gotten around to shooting it.

It was a great rifle shooting from a cold barrel, and I sout a few moos and a lot of deer with it that way.
 
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