Head spacing issue?

[louielouie]

I have a post-64 Win. M70 in 300 Win Mag that I'm not the original owner of. The throat was long enough to seat 200gr SBT to 'mag' length (3.57" OAL) so I removed the 1/4" spacer in the magazine and shortened the bolt stop and the rounds would cycle thru the magazine just fine.
What I've noticed is that one of the bolt lugs (engagement side) is shinier than the other so I spent some effort cleaning the lugs in the receiver. With the firing pin removed and the bolt handle down on an FL-szed R-P case (thickest belt-to-base) I can still push the bolt forward a "little bit" (don't have a gauge to measure with). It moves slightly more with no case. Accuracy is about 1moa with the right loads - especially with heavier BT's seated out to the rifling.
Is this typical or should I have a 'smith take a look at it? Maybe purchase some headspace gauges?

 

[Wally]

The safe thing to do would be let a gunsmith check the headspace. If you notice a crack running around your brass, just above the belt, after the 2nd or third firing, there's a real good chance you DO have a headspace issue.

Are you setting your dies so they just touch the shoulder on once fired brass?

Hope this helps,

Steve

 

[louielouie]

I normally neck size but FL for hunting loads and whenever camming the bolt becomes noticeably harder.
There is still thinning of the brass above the web so maybe I should at least get the head space gages since it seems that any 'smith work is gonna be $$$ enough to just throw another barrel on.

 

[Wally]

Sounds like you're on the right track to me. I wouldn't think a gunsmith would charge you too much to check the chamber with headspace gauges. But, if you want to buy the gauges anyway, then don't let me talk you out of it! :grin:

I hope everything turns out OK.

Steve

 

[6ppcar]

Get some lapping compound an lap the lugs until both the lugs are in full contact . Accuracy should be greatly improved. You may or may not have a head space problem , only checking with the proper gauges will tell.

 

[Antelope_Sniper]

+1 6ppc.

 

[louielouie]

As much as I love an excuse to buy more tools 'n toys, I'll take it to a 'smith and see what can be done with it. It's not a bad shooter but I just wanna be sure before my kid shoots it.

 

[Savage99]

With the firing pin removed and the bolt handle down on an FL-szed R-P case (thickest belt-to-base) I can still push the bolt forward a "little bit" (don't have a gauge to measure with). It moves slightly more with no case.

Every FL die for a belted case that I have ever used pushes the shoulder back too much. The effect is excessive headspace and early case failure at the expansion web.

I FL size my belted brass only enough to easily chamber it. Don't set the FL right down to the shell holder. Size a case and try it in the chamber until the bolt just closes.

Also make a feeler gage of a bent wire to reach inside each case to feel for insipient head separtions.