Head space measurement help

[JON8777]

i am working on a load for the 26" Encore. After decapping the brass last night I had a case split on me, about 1/4" above the rim.

The brass was factory brass that was shot and then loaded with 25g of H335, nosler 55gn bullet with a 6 1/2 primer.

How do I measure the headspace on the Encore and deterine if it was a faulty case or a head space issue?

[torpedoman]

cheap headspace measure. stack masking tape on the rim of the case til it gets tight then measure the tape stack with calipers.or measure the thickness of the tape, keep count and multiply to get measurement. cheap but it works.

[wallypedal]

Jon8777,
I'm no expert, but the only brass I ever had split was from Winchester factory .25-06 loads which I reloaded very carefully after the first firing in my rifle. Those split after a couple more loads that were not max. The only thing I could figure is that the factory brass was sized to the small (max headspace) side of specs, and the rifle's headspace allowed them to expand too much on first firing. All my other loads since (a lot!) have been in factory brass which I sized and trimmed before the first load.  No more splits - or incipient case head separations as gun writers who get paid by the word call them....
Tom

[epanzella]

i am working on a load for the 26" Encore. After decapping the brass last night I had a case split on me, about 1/4" above the rim.

The brass was factory brass that was shot and then loaded with 25g of H335, nosler 55gn bullet with a 6 1/2 primer.

How do I measure the headspace on the Encore and deterine if it was a faulty case or a head space issue?

The spec on the encore is the case head should be .001 from the firing pin bushing (breechblock). With the barrel off, take a sized case and  push into the chamber all the way. (make sure the rim is not hanging up on the extractor.) The measure how much the casehead is recessed or protruding from the barrel. Then install the barrel and close the action on progressively larger feeler gages to get the barrel gap. Combine this with the casehead measurement and you should get .001. If not, you can shim the firing pin bushing or add a shim under your sizing die.

[Hopalong7]

Question....was the split vertical or horizontal?  In other words, was it in line with the bore or perpendicular to the bore.  A case head separation caused by streaching brass will be perpendicular.  Walt 

[JON8777]

Perpendicular.

Anyone use that M b guys head space gauge? any thoughts on it?

[epanzella]

Perpendicular.

Anyone use that M b guys head space gauge? any thoughts on it?

I have one. It's a machined ss block into which you insert a dial indicator. The unit serves as a depth gage and tells you where the case head is in relation the the chamber end of the barrel. You take this measurement and combine it with the barrel gap when the action is closed to come up with the required .001. It's simple to use. You could also use a plain old depth gage but the block is the same OD as the barrel and helps you measure to the brass and avoid dipping the indicater tip into the primer pocket. 

[JON8777]

Heres What I have going on. I used feeler gauges and took the dimension from the max feeler gauge that alowed me to lock up the gun.



direct link to pic... Go2gbo is making the pic fuzzy

http://i133.photobucket.com/albums/q76/jon8777/223/Head%20Space/HEADSPACE.jpg

[JON8777]

First round I miss calculated the head space, I used 2x fired cases. Using virgin brass I got different dimensions.

I used multiple brass with the same results.

The Encore I believe the head space is from the firing pin plate face to the face of the barrel and then plus or minus case face in reference to the barrel face... correct me if I am wrong.

Here are my new dimensions for head space...

.223 = 0.010"
.300 = 0.012"
25-06 = 0.010"
209x50 = 0.013"

I ordered pin shims from Mike Bellum and I am going to try adding 0.009" of shim.

When I FLRS the .223 I get 0.004-0.005" difference in length.

[epanzella]

Heres What I have going on. I used feeler gauges and took the dimension from the max feeler gauge that alowed me to lock up the gun.



direct link to pic... Go2gbo is making the pic fuzzy

http://i133.photobucket.com/albums/q76/jon8777/223/Head%20Space/HEADSPACE.jpg

The dimensions in this drawing would require a .004 shim behind the firing pin bushing. This would leave .001 between the casehead and the firing pin bushing with the action locked.

[epanzella]

First round I miss calculated the head space, I used 2x fired cases. Using virgin brass I got different dimensions.

I used multiple brass with the same results.

The Encore I believe the head space is from the firing pin plate face to the face of the barrel and then plus or minus case face in reference to the barrel face... correct me if I am wrong.

Here are my new dimensions for head space...

.223 = 0.010"
.300 = 0.012"
25-06 = 0.010"
209x50 = 0.013"

I ordered pin shims from Mike (censored word) and I am going to try adding 0.009" of shim.

When I FLRS the .223 I get 0.004-0.005" difference in length.

"The Encore I believe the head space is from the firing pin plate face to the face of the barrel and then plus or minus case face in reference to the barrel face..."  That's it on the nose. Of course, it's important when setting up for .001 clearance that you have consistant cases as far as the shoulder datum to casehead length. If you necksize you should bump te shoulder to keep it from growing. If you want to get all calibers to the .001 clearance with the same frame, set the gun up for the tightest  one (in your case 223 or 25-06) and then shim your FLS or bump dies on the others to let them fireform to the same length. In the case sited above, shim the 300 die .002 and it should the have the same .001 clearance as the 223.