Scrapes on .308 Bullet

V

Vwalla

Inactive
I chambered a few reloaded 308 rounds in my M&P 10 and it marked the bullet (scratch at the top). Looks like the start of the rifling or maybe scraping the lower part of the chamber (feed ramp or lug). Is this normal? The COAL is 2.800 (a hair under) using new brass and hornady match 168 gr. Chambered 5 and all 5 made the same mark. Thanks.

see pic:
http://www.deltarefractories.com/IMG_2881.JPG
 
It's normal; contact with the feed ramp while chambering will usually leave some kind of mark. I doubt you are having contact with the rifling, as you would likely have to seat your bullet too far out to fit in a magazine.
 
Try to drop a round in the chamber by hand and then drop the bolt on it....

Usually feed scratches are longitudinal and rifling marks are circumferential.

Bullet seating marks are also circumferential. They are usually 0.10" higher on the bullet than rifling marks. That looks like a seater mark.
 
Take a dremel with pad attachment and rubbing compound. Work ar it enough and you can do away with those marks 100%
 
2.800" is too short, but those scratches don't matter. The seater button will make 'em. Oh, it's 3.340".
No rotary tools, period.
 
"2.800" is too short,...". According to the Lyman's book and Hodgon's website, this is the proper COAL for a 168 gr HPBT. I am picking up a Hornady book today as well (because I apparently like to pi$$ away cash:D).

Where are you getting this info?

(apparently they don't like the word pi$$ on this site:eek:)
 
Most of my magazine fed bolt actions leave a lot more marks than THAT from chambering.

That chamber is no padded cell. Getting in and out of there is like getting in and out of a condo timeshare contract.
 
Why are you worried about some scratches on your bullets? Have you ever recovered any fired bullets? The effects of the rifling and it's reaction to 50,000 pounds + of pressure and the abrupt action of chambering will leave a lot more marks on a bullet. It can still hit the target quite accurately even though it looks like a mess.

Worry more about how it lines up with the chamber once it is ready to fire. If the marks actually move the bullet, IOW knocks it off center, THEN that's something to worry about.
 
2.800" OAL is correct. That is the standard setting for 168 gr HPBT 308 cal. will shoot in every 308 just fine.
 
thanks cw308!

snuffy: I have never recovered a bullet, nor have I paid attention to any factory made ammo after I have unchambered a live round. Being new to reloading (prob should have stated that), I'm just making sure all is copacetic before firing these first hand loads through my rifle. Dont want to deal with that 50,000 lbs of pressure incorrectly :D
 
According to the Lyman's book and Hodgon's website, this is the proper COAL for a 168 gr HPBT.
Click to expand...
I disagree. That COAL number's only what they chose to use for their tests in their barrels. Anyone can use another COAL if they choose to; many have.

Depending on the chamber's throat angle and distance from the chamber mouth, and how much wear it's had since new, the bullet's jump to it will vary some amount. There can easily be 1/10th inch spread.

I've loaded .308 Win. ammo with Sierra's 168's out to 2.90" COAL; bullet was barely held by the case mouth. And they fed from the box magazine just fine. As the barrel was almost worn out, they had to be set that shallow in the case neck to shoot accurately.
 
Clark said:
That chamber is no padded cell. Getting in and out of there is like getting in and out of a condo timeshare contract.
Click to expand...

AMEN BROTHER!

Rotary tools leave a rotary scratch, no matter if it's fine grit buffing compound.

A CLEAN CUT is the best start,
Then work a case or chamber dummy in and out with lapping compound to polish the chamber.

Remember to UNDER SIZE the case slightly, so you don't OVERSIZE the chamber. The buffing compound WILL add to the case you are using to buff the chamber.

VERY fine scratches that go LONGWAYS with the chamber won't mark the case/bullet nearly as much as scratches that go around the chamber that work like a file when the round chambers.

Varmint and field rifles won't need the chamber polished to the 9th degree,
If you are bench rifle shooting... Maybe so...

In my experience (Personal Opinion Warning Here),
A clean chamber cut, VERY little lapping, if any, is required.
If the chamber cycles well, doesn't leave radial impressions on the case, then the chamber is good.

With MODERN CNC machining of the chamber cutters themselves,
You rarely see the metal file rough chambers you used to run into when people were cranking out 'Sporter' barrels for all those WW II surplus rifles years back...
They were a NIGHTMARE to do anything with.

Back then, a lot of guys tried to sharpen, or even make chamber cutters themselves, and it was a pain in the butt for guys wanting to actually HIT something,
And get the brass to extract from the chamber afterwards...
 
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