Gunsmithing 338 bore diameter

[jonaddis84]

I am having some serious accuracy issues with my new Savage 338. Wondering what the bore diameter should be normally? I have a PTG indicator rod set for 338 and with the .3306 bushing in it is still loose, which is the biggest bushing I have.

Could this be causing 2-3" grouping at 100yds no matter what I do with the loads?

Thanks

 

[bohem]

Re: 338 bore diameter

It might but that's still not as loose as I would expect, can you slug it?

If you have access to 38spl soft lead bullets you can run one of those through the bore and then mic the 2 diameters on the barrel.

 

[jonaddis84]

Re: 338 bore diameter

When you say not as loose as you would expect, do you mean Savage is known for loose bores?

I have some lead cast 9mm bullets, they are wheelweight lead though, should I cast some out of pure lead?

Then how do I go about slugging it? Just push it through with a ramrod?

I just faced off the action on my truing jig, it had a pretty nasty booger on it from the factory, however it did not take much to square it off, not near as bad as my 308 action was.

I have a new recoil lug coming from SSS tomorrow, my HS gauges came today from PTG so hopefully Ill be able to test it out again soon.

 

[Spuhr]

Re: 338 bore diameter

My TRG is .3299
Håkan

 

[bigngreen]

Re: 338 bore diameter

I just had a Brux .338 barrel in the lathe for a 338 RUM and .3304 was perfect with .3306 a little on the tight side.

 

[jonaddis84]

Re: 338 bore diameter

If I had to guess, based on my experience with other barrels, I would need a .331 bushing to make it snug in there.

I have some cerrosafe, maybe I will try to make a cast of the chamber and part of the bore this weekend. The indicator felt the same at the chamber end as it does in the muzzle, so I dont think its tapered at all.

I could definitely see a bore being .001 larger than it is supposed to be degrading accuracy, but I guess I'd have a hard time believing its giving me the erratic groups Im seeing.

Its not like its stringing horizontally or vertically, they are just all over the place. Im sure my loads still need work, but Ive never experienced a rifle that shot this horribly even when the load was at its worst.

Im basically eliminating anything that could be wrong with it. The action got faced off today, I will headspace it properly as soon as I have the new recoil lug (although I trial fit the headspace today and it looks to be lined up exactly how it was from Savage, so I dont believe the issue was with excessive headspace.)

The only other thing I feel it could be is the base, although I torqued it down, maybe it is still sliding under recoil... Id hate to bed it down and have to send the rifle back in to Savage and have them tell me its not warranted anymore.

 

[bohem]

Re: 338 bore diameter

I haven't heard of Savages being known for big bore diameters. What I meant was that for a degradation in accuracy I have seen rifles shoot like piss but the bullets were about 0.002" undersize (or the bore and groove dimensions were 0.002-0.006" oversize).

Mosin Nagants are notorious for this and I have 2 different sizes of bullets from the 2 that I still reload for (1 mine and 1 my brother's).

Have you checked the crown to make sure it wasn't boogered up somehow?

 

[Stonewall2]

Re: 338 bore diameter

Try shooting some flat based hunting bullets i.e. Speer 200 gr.

The Lapua .338 bullets are .339 diameter I believe.


Glenn