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Old February 14, 2013, 02:41 PM   #25
Senior Member
Join Date: June 22, 2009
Location: South Carolina
Posts: 167
Sir, would it be possible for you to supply more information regarding this condition? This is a very interesting event.

Could you please photograph:

1. the back of the broken receiver close for us to see the fracture better?

2. the top of the receiver hump showing the manufacturer and serial number?

3. the bolt face of the rifle?

4. the entire top surface of the bolt with another close up of the font on the bolt?

5. the piece of the horseshoe that broke off showing the fracture surface.

6. the fired case that did the deed with close ups of the primer to show the dimple details? As well as other cases fired in same rifle.

7. the magazine area with bolt removed all areas?

8. the bedding of the action.

9. picture of the striker removed from the bolt top and bottom.

10. now this is as stretch , could you get a long vernier caliper and get the measurement from the center line of the gas port to the back of the receiver to 3 decimal places? Also from gas port to front of the receiver.

Could you measure:

1.the inside diameter of the Wilson case gage at the bottom with hopefully a digital caliper or hole mic? I have measured three Wilson case gages for .260, 7/08 and 308 and I get measurements of .4725, .474 and .475. Since the chamber dimensions are called for at .471-.473 range and assuming your Wilson gage measures like mine then every fired 308 case in history should fit in your gage with a .474 or .475 base dimension.

2. the inside diameter of the rifle chamber at the same point? Again this should be .471-.473 range but I have seen fired cases as large as .475 which means they were most likely fired in a .476” chamber.

3. the diameter of the case that did the deed in two orientations .200” up from rim?

4. the diameter of the home made case gage at the lower mouth opening? Making a case gage with a chamber reamer that was used on your rifle is good if you want check your range pick up cases after full length sizing to see if they will go in your chamber. I have seen very few rifles you could pick up brass fired in others and chamber in another.

5. the diameter of the fired case in the case gage in the picture.

6. measure the striker for overall length from striker nose to back of tail. Diameter of striker nose, diameter of the support shoulder immediately to the rear of the striker.

7. how far did the shoulder move forward on firing the suspect case?

8. how did this measurement differ from other cases fired in this rifle?

9. If you have access to a Rockwell tester I would like to know the readings of the receiver in multiple places. For instance starting ¼” from receiver face take readings all the way around the receiver every half inch from front to rear.

10. Same for the bolt, readings on both lugs in all over bolt.
From the loader of the ammo his definition of improperly sized. i.e. case shoulder not set back far enough or shoulder set back too far? Was bolt binding up with the turn in to battery?

11.The load he was using including primer, propellant, bullet, case manufacturer and history i.e. number of loadings etc. Was bullet .308” diameter or?????

12 The length his cases were trimmed to?

13 The FL sized dimension of the case bases measured .200” up from rim.

14The neck dimensions of loaded ammo and fired cases.?

15The bore dimensions of the barrel. Land and groove? Who made the barrel?

16The manufacturer of the reamer? The dimensions of the reamer to correspond with case measured .200” up from rim to include neck dimension.

17Gas port dimension of barrel?

18Manufacturer code of the magazine he was using?

19How much striker nose protrusion from bolt face?
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Last edited by Hummer70; February 14, 2013 at 03:34 PM.
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