I will be testing a 270win with 2 different bullet weights at about 2800-3000fps. I have 10 rounds for each bullet. The barrel is clean and will be fouled before testing. My question is, how often and how thorough would you clean with this many shots? I plan on completely cleaning between the two different bullet weights and fouling.

Well, the funny thing about rifles is that you never know what you are going to get. You may have a rifle that shoots best when "dirty." You may have one that is at its best when cleaned to bare metal. Only time and testing will tell.

But, to be fair to both of your loads, you should start out with a clean bbl for both, as that is one variable you can eliminate.

Also, make damn sure your bore is DRY before shooting it. Don't go to the range with a good layer of bore conditioner or oil in it and shoot it out.

I will assume that your test loads have been proven to be safe and now you are narrowing it down to these two for accuracy. Since you loaded 10 each, I will also assume that it is a possibility that you will start with a clean barrel, shoot one fouler, then three 3 shot groups of each. Good start if so.

What are your loads? I load for several 270s as do a ton of other AR members. We'll be happy to lend a hand with experience....powders, bullets, etc.

Even though I'd probably change my mind 20 times about powders, I'd say if I had to choose one for the 270, my answer tonight would be H4831SC. Tomorrow I may say IMR4350, and on Monday I will likely migrate to Re22 or Re19. The fact is, so many powders work so dang good in the 270, you can have 500 rounds through one and discover you have 10 excellent loads.

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I will be testing a 270win with 2 different bullet weights at about 2800-3000fps. I have 10 rounds for each bullet.

When you say 10 rounds for each "bullet" are all loaded with the same powder charge? In working up a load in a cartridge the size of a 270 Win., I would generally start with 3 cartridges each set of 3 with a 1 grain incremental increase in powder charge. Using this method I can tell if the pressure is OK and also get a very good idea of accuracy. Once I find a combination that seems to work, I'll load up more cartridges with that load and test it more extensively.

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The barrel is clean and will be fouled before testing. My question is, how often and how thorough would you clean with this many shots?

With my method, I would put at a maximum about 15 rounds through the gun before cleaning if it's a new barrel. I'm not so picky with an older barrel. The cleaning would be thorough to the point the patches came out white.

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I plan on completely cleaning between the two different bullet weights and fouling.

It certainly doesn't hurt to do it this way but it's probably a bit more work than you need to go to. You don't need to clean between different bullet weights and I also believe it's fairly uncommon for fouling shots to be really needed (but of course, my guns are different since the manufacturers only sell me the good ones).

I believe the most common reason for fouling shots to appear to work is because of the thin layer of oil many leave in their barrels after cleaning. Leaving this oil in the barrel and shooting it out can harm the barrel and will markedly change the impact point for the first 3 to 5 shots. If your last coating in the barrel is some solvent like Microlon Gun Juice or Prolix, you won't have the clean barrel "fliers."

When load developing, I try to clean the barrel between 15 and 20 rounds fired. And I only shoot 3 shot groups for each different loading.
For factory barreled rifles, where the barrel is not lapped by the maker, I scrub it about 100 strokes with JB Bore Paste to polish out the tool marks. For custom barrels that are lapped by the maker, I just shoot them as is.
I also use good bench equipment to do the load testing, a good front and rear rest.

Don

I clean between each batch of reloads. Shoot a couple foulers and contiue on another target.
Also its important to let the barrel cood down after each shot or string.with the 270 can shoot three shot strings.

The 270 I'm loading for is an old friend, a Husqvarna I brought back from Germany 35 yrs ago. The barrel will be clean and dry. I've loaded a 130 Rem psp with IMR 4350 in .3grn increments, starting at 51.3 and ending at 54.0 The 140 Horn BTSP is also loaded with IMR 4350and starts at 50.3 and ends at 53.0 I will be shooting 10 shot strings looking for barrel nodes

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Originally posted by Lostone:
The 270 I'm loading for is an old friend, a Husqvarna I brought back from Germany 35 yrs ago. The barrel will be clean and dry. I've loaded a 130 Rem psp with IMR 4350 in .3grn increments, starting at 51.3 and ending at 54.0 The 140 Horn BTSP is also loaded with IMR 4350and starts at 50.3 and ends at 53.0 I will be shooting 10 shot strings looking for barrel nodes

You probably have a featherweight chrome moly bbl, correct? If so, it will heat up very quickly. LET IT COOL b/w shots and shot groups. Unfortunately, shooting featherweight bbls in the summer makes for some long rangetime while waiting for cooling. I always prop my rifles upright to let the heat escape the bbl quicker b/w firings. Unless you have a wind blowing directly into the muzzle, then I leave it on the bench.

"..make damn sure your bore is DRY before shooting it. Don't go to the range with a good layer of bore conditioner or oil in it and shoot it out."

Amen to that. I find that the first shot out of a clean barrel almost always strikes in the group IF I first run a wet patch of Hoppe's 9 in it to clean out any residual oils AND follow that with three or four clean patchs so all oil residue from the Hoppes is gone too.

Hunting rifles are fired cold. Testing almost certainly will be more valid if the barrel is allowed to cool to ambient temp before the next test shot. It can make for a lonnng day at the range but it's the only way to get solid results from a sporter barrel.