6mm Rem - VVN560 problem

R

realm-aw

Guest
A friend brought out a Rem 700 in 6mm Rem, a used gun he had traded for. After firing 30+ rounds he had a severe pressure problem. The problem round was stuck in the bolt when he was able to get the action open. The ejector pin was jammed flush in the bolt face. The primer fell out of the expanded primer pocket. The casehead measured .486 vs. .466 on a new unfired case. The load was 46.5 gr on VV N560 behind a 75 Vmax. Brass was trimmed to length 2.322 which is .010 under max case length. OCL was 2.925 using new WW brass.
He was trying to work up a conservative load, but had no firm data on the N560 for the 6MM. Has anyone had a pressure problem with VV N560?
 
if he had no firm data,,,,,,, what in the hell was he doing for a starting point?????
 
Well yes...

Yes that question seems to come up in the perfect clairity of hindsight. I should have mentioned that we are looking at his actual chamber lenghth, there may be a carbon build-up that is causing a restriction.
Has anyone had pressure problems with N560 or are the WW cases more suspect? I am just trying to narrow the field of suspects. Any help is welcome.
 
You can go here: http://www.eabco.com/VihtaVuori01.pdf ---if you haven't already---might help alittle although they do not list a load for 6MM.

Also, you did not mention what primer was used.
I use Vihtavouri in pistol loads and at least in the powders I use, a magnum primer is a no-no--produces pressure spikes.

Rich
 
sorry

Sorry but I do not know the primer he used, although I do not think it was a mag primer. We checked the chamber with a 6mm reamer tonight and there is no obstruction. The plan is to switch to a published load with 4350.
 
You sure made it hard on yourself...

with no known loading data, magnum powder with a light bullet. Conservative loads with slow burning powders with light bullets is a recipe for disaster causing extreme pressure spikes.

Close to max loads or Max loads of Win 760 and IMR 4064 in a win case with a Fed 210, 75g bullet touching the lands produces spectacular accuracy and blistering speeds.

Win 760 is very easy on barrels chambered in 6mm Rem, very fast and accurate with 60,70,75 and 80g bullets.
 
Quickload data

I asked someone on a different forum to run this load in QuickLoads. Below are his results. Even with a 10% lot-to-lot variation, it is still not beyond max. pressure in a 6mm Rem. I would strongly encourage your friend to have this gun inspected by a gunsmith before proceeding. At minimum fire it with sand bands and a string to avoid injury.

Make sure he doesn't have 25 cal 75gr Vmaxs. I actually picked up a box of 25 cal 75s instead of the 6mm and made it all the way to start seating bullets below I figured out my mistake. I gave those things away so I would make that mistake again.

Be safe and luck, tiny

__________________________________
QUICKLOADS data

Cartridge : 6 mm Rem.
Bullet : .243, 75, Hornady V-MAX 22420
Cartridge O.A.L. L6: 2.925 inch or 74.30 mm
Barrel Length : 24.0 inch or 609.6 mm
Powder : Vihtavuori N560
Predicted data by increasing and decreasing the given charge,
incremented in steps of 2.0% of nominal charge.
CAUTION: Figures exceed maximum and minimum recommended loads !

Step Fill. Charge Vel. Energy Pmax Pmuz Prop. Burnt B_Time
% % Grains fps ft.lbs psi psi % ms

-20.0 76 37.20 2385 948 20032 7406 66.7 1.579
-18.0 78 38.13 2447 997 21261 7748 68.4 1.543
-16.0 80 39.06 2510 1049 22570 8094 70.2 1.509
-14.0 82 39.99 2574 1103 23966 8443 71.9 1.474
-12.0 84 40.92 2639 1160 25453 8794 73.6 1.441
-10.0 85 41.85 2705 1219 27040 9146 75.3 1.408
-08.0 87 42.78 2773 1280 28731 9498 76.9 1.375
-06.0 89 43.71 2841 1344 30535 9848 78.6 1.342
-04.0 91 44.64 2910 1410 32462 10196 80.2 1.310
-02.0 93 45.57 2980 1479 34510 10540 81.8 1.279
+00.0 95 46.50 3051 1550 36721 10878 83.4 1.248
+02.0 97 47.43 3123 1624 39074 11210 84.9 1.213
+04.0 99 48.36 3195 1700 41598 11534 86.3 1.177
+06.0 101 49.29 3268 1778 44301 11849 87.8 1.143
+08.0 103 50.22 3341 1859 47200 12153 89.1 1.109
+10.0 104 51.15 3415 1942 50314 12446 90.4 1.076

Results caused by ± 10% powder lot-to-lot burning rate variation using nominal charge
Data for burning rate increased by 10% relative to nominal value:
+Ba 95 46.50 3289 1801 44480 11794 92.2 1.141
Data for burning rate decreased by 10% relative to nominal value:
-Ba 95 46.50 2781 1288 30017 9486 71.8 1.354
 
My experience with 500 series Vit powders

Is they are very temperature sensitive.

What temperature was it the day you shot. Were the rounds left in the sun?

I have a 6mm Rem Imp'd that only sees Vit 165, I would never consider the 560.

JMHO

Randy
 
thanks to all

Thanks to all for the input, sorry I don't know the details of heat or primer type. A gunsmith has looked at the chamber and he has been advised to proceed with caution.
 
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