Learning curve for a 338 LM owner

[hafejd30]

I wanted to share my recent experience with other 338 owners.

As of lately I've got around to shooting my 338 LM more. However I've noticed the groups have gone to crap. I kept switching powder/seating depth etc etc etc to no avail. I then got some advice from others more experienced in this rounds who told me the barrels foul out quick with 338's due to the bullets and powder capacity. Another 338 shooter said his goes about 10 rounds and accuracy falls off. So they need to be cleaned more often that other rounds. So I tested this theory yesterday.

Fired a group with a dirty barrel, Proly 25 ish rounds through it. Shot the first 3 shots into 14" at 800 yards. This is the issue I was having lately with depleading accuracy. It never even crossed my mind that a barrel can foul out this quickly. I gave the gun my usual cleaning regiment (takes about 15 min) then took it back to the same spot to retest.

The group is shown below. The clean bore shot is circled in pen. Then I proceeded to shoot a 3 shot group. All 4 shots held inside 3 inches at 792 yards.

I thought this may be useful to other 338 guys (and this isn't just a lapua thing but all 338 running heavy bullets/charge weights). I don't mind cleaning as this rifle doesn't get used for much other then LR hunting. I was just not used to a rifle fouling out this quick and it sure did cause some headaches.

I would've loved to see this advice on here a few months ago and hope this post may help someone in the same predicament. I'm used to cleaning after 100+ rounds with my 260 but the big boy rifles are apparently not that forgiving.

Other feel free to chime in with your 338 experiences because there is someone out there like me who would benefit from such a simply overlooked problem

Quarter in picture for comparison

338 LM
792 yards
Shilen Select Match 30"
95.5 gr RE 33/Lapua Brass/CCI 250/300 SMK

[yobuck]

Well that's certainly good shooting, so I think it boils down to what you have to do to shoot well with your gun.
The 338s we use have Benchmark barrels which are probably no better than many others available.
But I cant say ive noticed any major fall off in accuracy when fouling takes place.
But then we don't shoot for groups either with those guns. We simply practice on rocks at distances over 1000 yds
and are content with minit of deer accuracy because that's all their used for.

[Keyhole]

You may just barely be cleaning it enough to get your accuracy back, but not really clean. You should try some of the kleanout foaming bore cleaner you can get at academy. Fill the barrel with it and let it set for ~1h and repeat until all blue and powder is gone. It will not harm your bore and you don't even have to scrub. If after that you still feel snags or tight spots when you run a patch get some JB bore paste and scrub the bore how the directions say until the patch slides smooth. I had a 6BR barrel that stopped shooting due to a powder/copper buildup at the throat and doing this saved it.

[Zero333]

Nice shooting. 5 or 10 shot groups are for measuring precision, 3 shot groups are for dialing accuracy.

I have to agree with the above post that it's not easy to clean a barrel down to bare metal. There is always some copper that remains unless you use some of those foaming bore cleaners and leave them in or Montana X-treme copper solvent or CR-10.

I have a few Shilen barrels and they indeed shoot best when nice and clean.