Shooting a 308 remington barrel with a 311 throat and around a 309 dia barrel. Shows real promise- ran some 165 Hornady [.3081 dia.] thru, and it fouls out at 14-15 rds. Groups make a largish hole prior to this jacket material covering the land tops. No fouling on barrel walls-- course it isn't bearing on them. Could the hot gases blowing by accentuate this fouling? Could be due to only bearing on the land tops- and that coupled with some minor degree of slugging produces this fouling?

Aladin - 14 to 15 rounds between cleaning should indicate a considerable amount of fouling. This is not abnormal. Much depends upon the quality of the barrel, jacket material, and how the barrel was broken/lapped in. I clean between 5 and 10 rounds while at the range. If I stretch it, then all I am doing is wasting shots and causing more wear on the barrel.

Depending on the barrel manufacturer�s break in procedure, you may wish to use some JB and lap the barrel or go through the one shot and clean routine for the first 10 to 15 rounds and then three shots and clean till 50. After this, you may only want to shoot strings of 5 to 10 between cleaning.

To measure blow by, you may want to chrono your load and compare your velocities with the load tables.

Z

aladin,

I have an M1A with a Douglas barrel in 308 that easily and routinely goes an 88 round match without cleaning. That's with 168 or 175 Sierra Match Kings at 2615 fps. No discernable group change and three-patches- of-Hoppe's-#9 fouling.

I have a 416 that used to be heavily fouled in three rounds, but is now only lightly fouling. Why the change I do not know.

If I knew what made the difference I'd be a rich man. I hear that even Shilen makes a barrel that mysteriously fouls badly every now and then. I do know that my better barrels foul least from the start.

I have never heard of a Krieger that fouled, so it might be a grain-structure issue from the button rifling process.

My only advice is to firelap the barrel or clean w/CR10 and RemClean every round until it polishes itself. I know I'm not telling you anything new.

I don't know why, but sometimes it seems that a powder change can lessen fouling. I used H380 and Speer 350 MagTips in the 416 for a while, and that seemed to be when the barrel began to break in.

Don

Don: to be sure, I indict the Hornady's to some extent. Good folks over at Grand Island- I used to live in NE, but-- the Horn's I've shot seem to foul easier than say the Speer's. Or Noselers- as I call'm.

I'm firelapping with speed. Cast as 1800-2100-- putting the polish in the bore area I think is too restricted. Funny thing is-- the #7 load at 2100 puts the boolit right in the group-- shot over a healthy dose of chrome polish. Go figure.

Think I'm almost there. Might well have a good cast barrel yet.

Bonded core bullets tend to foul more heavily than non bonded core bullets. If the rifle is prone to fouling, shoot it in with non bonded core bullets till it is polished. Once the bore is broken in, the difference in fouling between the two types of bullets will be less noticeable.

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Gerard Schultz
GS Custom Bullets

Gerard: I think the time and expense to lap a barrel by normal shooting isn't practical. And especially for a bad fouler- which needs more immediate attention. And I don't subscribe to the charged bullet concept of firelapping-- too many knowledgeable shooters report throat enlargement. My personal method involves putting the polish into the barrel and firing over it. It appears this works much faster. I use cast bullets that fully fill the bore- another point I take issue with in regards to firelapping with jacketed slugs. Often they aren't filling the bore completely.

I'm making a study of lapping and firelapping bores-- of sorts. Really need a bore scope, but the expense is prohibitive. I use varying size slugs and measure by feel.

Zero Drift: I owned four 220 Swifts- all Rugers. I jacket fouled a bore with one once due to an reloading error-- but nothing to the extent of this one I'm working with now. I learned to clean those effectively and fast- and made them much better shooters. But I would submit a bore that goes away before 15-20 rds is doing poorly. By more than doubling it's group size. I've owned several guns that shot well without cleaning- for more rds than I care to admit to. Think it all comes down to internal dimensions-- uniformity damages the bullet less and therefore fouls less, I guess to state the obvious.