Some pressure related questions following some load devolopment on my 7x57 Argentine 09 actioned sporter:-

Will a min length chamber and longish new brass (such that the bolt experiences a bit of resistance on shutting) likely cause a false indication of XS pressure by 'binding' the brass to the walls of the chamber earlier.

What pressures are advisable long term in an 09 Argentine?

I've had some really good results with the 150gr scirroco in my 7x57. I used new RWS brass unsized which had just a small amount of resistance on bolt shutting (empty cases), the bases indicating headspace was tight.

42gr VVN150 gave 2,670fps and 0.6moa with normal bolt lift.

One shot of 47gr VVN160 (but mag primer)gave 2618fps, normal bolt lift.

48grgave 2735fps (0.9moa but real accuracy not known due to crap shooting)A couple of extactions had a tad of resistance at the last inch of bolt lift but one didn't. As the primer of the one that didn't was flat and the others weren't this seemed to point to me that the tight headspacing of the cases was to some extent responsible for the bolt lift.

49gr gave 2675, 2775 and 2784pfs with 0.6moa. All had normal primers but slight bolt lift resistance on the last inch.

I relubed the bolt and tried one of 50gr which gave 2840fps and real bolt lift resistance. The rest were pulled as this is definately not territory I want to get into.

I'm tempted to rerun the VVN160 series with full length sized cases but start lower in case pressures really are up there. I seem to remember that shorter cases with high pressure are really bad news for setting back mauser lugs.In case you wonder the mag primer is to reduce muzzle flash. Even if it increases burning rate by 10% quickLOAD still predicts pressures no more than 52.5kpsi for this velocity. Could it do more than that with a slightly compressed charge?

What do you think?

If I run through the sheer stress on the two forward bold lugs, the 98 action is plenty strong for safety.

But if I look at the lug contact area, some have very little contact area, and might dent and increase headspace.
I have read how others lap the lugs until they get some great amount of contact area, but my standard is that more steel area must be in compression than case head area touching the bolt face. I lap with the bolt and sear assembled so that the surfaces are the same that will be used.

Once I am satisfied with the bolt lug contact, I am not afraid to work up a load in 1903 Turks, 1938 Turks, or VZ24's until the bolt gets sticky. I then back off on the load to allow for temperature and ammo tolerances or to a high accuracy node.

Well, I've had both a 6.5 Gibbs and a 6mm/284 built on Mausers, and have fired some pretty warm loads in them, and nothing untoward has ever happened. I also have a Venezuelan FN Mauser in 7X57, in which I am now using a load which generates 2720 FPS with a 175-grain bullet from a 22" barrel, and it has stood this load now for almost 20 years with no change in headspace....

I like the 1909 Arg. mauser and have several.
I do not load them for anything more than 52,000 tho I might if the action was worked over but then I would more than likely just buy another rifle

I was plagued with sticky bolt lift with what appeared to be normal pressure reloads. Turned out to be somehow connected to using full length size dies to partially resize cases. I set the dies to properly full length size cases and the problem disappeared. Another thing that will cause higher than usual pressure is over length cases. My Sellior & Bellot cases were 15 thousandths over when once fired with the factory load that came in them. I feel that partially sizing cases with FL dies increases case length unreasonably.

300,
When I put 52 gr IMR4895 200 gr FMJ in a 1903 8x57 Turkish Maauser, I get a sticky bolt that is not caused by improperly resized cases. It is an overload. Quickload estimates 68 kpsi.

1894

Has your action been rehardend or heat treated by the gunsmith when it was converted ?
You should actually contact D'arcy Echols since he has used the argentine for his classic rifles, Jbelk would also be able to give you a good answer. I 'm not sure and therefore don't want to give an incorrect reply.

I have two FN mausers that are very hard and the entire receiver and have been rehardend completly. I think the Argentine is like the old mausers surface hardend and when it loosens the action will give up very easy if you are unlucky.

Reload with care, consult a manual if possible.

/ JOHAN

P.S. is it possible to see some pictures of your rifle. I will soon have a few mausers started up for rebuilding and need some inspiration Who has built your?

[ 03-07-2003, 23:48: Message edited by: JOHAN ]