338 Lapua LRH bolt head hitting factory barrel

[geezerhood]

I was installing a new X-Caliber 338 Lapua barrel on my Savage LRH action and wanted to set the headspace a bit tighter than where it was from the factory and discovered that the front edge of the bolt head hits the back of the new barrel AND the original barrel when set snugly with a "Go" gauge, making bolt closing VERY difficult. Both barrels are chambered perfectly so it wasn't a chamber depth issue.

I removed 0.003 from the front of the bolt head and now it BARELY clears the barrel when headspaced snugly against the Go. I noticed that the 338 sized bolt head is quite a bit different than my standard "Magnum" sized bolt heads besides just the opening width for case. The bolt face is significantly deeper (a bit too deep on this one apparently) and the lugs are quit a bit longer. The bolt face has machining marks on it. None of my others bolt heads show this. Original owner did not do anything to the bolt face so that must have happened at Savage. The head has a serial number on it that matches the action.

Magnum bolt head
Front edge of head to bolt face distance = 0.113 (only checked one)
Thickness front to back of bolt lugs = 0.487 to 0.502 (checked several)

338 Lapua bolt head
Front edge to bolt face distance = 0.128 before shortening / 0.125 after
Thickness front to back of bolt lugs = 0.553 (before shortening) / 0.550 after

I am assuming that 0.003" is not enough to be nervous about as far as weakening the bolt lugs are concerned. I measured a half dozen 308 sized and magnum bolt heads and the lug thickness varied from 0.502" to 0.497" ~ 0.005 is more than my 0.003" reduction.

Have any of you out there also had issues like this or others, with the 338 Lapua bolt heads? I have never had this type of problem with my other Savage bolt heads x about 20.

[sinman]

Chamber depth is the issue, a lot of guys don't realize the difference in bolt heads and set the chamber depth the same as any other savage barrel. I have fixed quite a few prefit barrels for customers that bought them elsewhere and were having brass problems. Prefit barrels don't like to be headspaced off of the face of the bolt.

[geezerhood]

Chamber depth is the issue, a lot of guys don't realize the difference in bolt heads and set the chamber depth the same as any other savage barrel. I have fixed quite a few prefit barrels for customers that bought them elsewhere and were having brass problems. Prefit barrels don't like to be headspaced off of the face of the bolt.

This does not make sense to me. I would not want the chamber any more shallow than it already is - the chamber is absolutely perfect and the way I want it to be. If I am understanding what you said the only way to avoid hitting the rear of the barrel with this bolt head, unmodified, would be to have the case protruding further out of the chamber. Something I absolutely do NOT want.

The factory barrel is also chambered to virtually the exact same depth as my X-Caliber within 0.0005

[sinman]

But it's not perfect, if it was perfect your bolt head wouldn't hit. Each and every rifle has a different design for a bolt, each will have a case/gauge protrude past the end of the barrel differently. You used the stick out from a Savage and chambered a Remington 700 barrel that way you would have a lot of trouble and probably an action in pieces. Depending on use of rifle will give you distance between the end of the barrel and the bolt. You wouldn't want .003" gap in a tactical/hunting rifle because one piece of dirt/grass/etc would lock your bolt up where as for a bench gun it is perfectly fine. Most guns run .005—.010" gap between the bolt face and barrel. Also just because the factory barrel is that way doesn't mean it's correct, the Savage 338 lapua barrels are some of the worst they have ever built.

[sharpshooter]

The nominal depth for a .338 Lapua bolt head is .130". The go gauge protrusion is .140-.145". Most new barrel makers are not aware of this.

[geezerhood]

Thanks for all the great information guys. Good to hear it from those who deal with this stuff every day.

It sounds like the bolt face depth was in fact pretty close to correct at 0.128. As it shipped from the factory it was fine. Factory and reloaded ammo shot well and showed no problems, but it was not tight enough for me. I like a snug fit with new neck sized cases. (Bench shooting at 1000-1500yds, not hunting).

I measured the gap between the front of the bolt and the rear of the barrel it is is 0.0045 to 0.005 which should be fine for target shooting but on the thin end for hunting / tactical. I can live with that. When I put the original stock and barrel back on for hunting next year, I will set the headspace back where it was.

I run my 338 Lapuas close to max and I really don't want anything but the portion of the case from the beginning of the extractor cut rearward hanging out of the chamber unsupported. Even if it is how it is supposed to be I don't want it that way. This is working really well now and I am very pleased that I was able to make it work by taking a few thousandths off the front of the bolt, rather than exposing the case walls with a shorter chamber depth.

I wonder if this photo of the PTG 338 Lapua Savage bolt head is of an actual item. If it is the lugs sure do seem shorter than the Savage 338 Lapua bolt head. It appears to be the same as the regular magnum heads.