measuring 5 groove bbl.

[porthos]

have taken pound cast's of 2 enfields. i think that there is a "trick" to measuring the groves of the 5 groove bbls. can someone refresh my memory??

[para45lda]

Not sure if you've searched here yet but I know I saw it a few years ago.

http://castboolits.gunloads.com/showthread.php?149803-Actual-barrel-dimension-of-bullet-size-for-the-Lee-Enfield

[Gtek]

#1- A dial caliper I would call close, a real mic better choice. Find a soda can and cut off top and bottom with scissors, cut side to create a sheet. Cut strips the width required for your given area of intent. Measure strip thickness, = (x), I wrap boolit and light pinch off backside with hemostats, measure total and then subtract the thickness of can x 2 = your slug. Works good enough for me. There is a fancy drawing requiring process of a triangulation method, but-----

[Nobade]

I use a V anvil mic designed for measuring 5 flute objects. Got it for measuring throating reamers and such.

[midnight]

I use two v-anvil micrometers, one for three fluted objects & one for 5 fluted objects. A machinist with a lot of tooling should have one & may measure for you. I have also seen the dimensions of a v-block used to do this. I have it around here someware. Using the search function should find it. I decided v-anvil micrometer was the best solutiom.

Bob

[Goofy]

A more detailed examination with measuring a wrap around with pics:
http://www.texas-mac.com/Measuring_Groove_Diameters_of_Odd_Groove_Bores.htm l

[mdi]

The above answers are good, and I can only add what works for me. Life long machinist/mechanic with a good feel for micrometers here. I can slowly spin a cast bullet in my mikes as I slowly close the spindle and "feel" a good measurement. I have checked my method against the "wrapping" method and get accurate measurements with my method...

[oley55]

A more detailed examination with measuring a wrap around with pics:
http://www.texas-mac.com/Measuring_Groove_Diameters_of_Odd_Groove_Bores.htm l

I prowley won't be trying to use the Powley formula. Just saying...

An aside, soda cans are not perfectly uniform top to bottom (+/- .0005"), which only makes sense when considering the pressing/forming process. To eliminate this tiny variable, cutting your strips following the radius of the can will be more consistent.

[vagrantviking]

The above answers are good, and I can only add what works for me. Life long machinist/mechanic with a good feel for micrometers here. I can slowly spin a cast bullet in my mikes as I slowly close the spindle and "feel" a good measurement. I have checked my method against the "wrapping" method and get accurate measurements with my method...

This is what I do. The high points on the corners come very close. Plenty close enough to get a starting point for 2 to 3 thousandths over size.

[oley55]

This is what I do. The high points on the corners come very close. Plenty close enough to get a starting point for 2 to 3 thousandths over size.

yes and no. Take my Ruger Speed-Six which always seemed to be trying to lead, but never severely. Using the shim wrap method I confirmed my cylinder throats were only .0008"-.001" over groove. A 2-3 thou guesstimate would be/was meaningless in this situation. After nearly four hours of slowly honing my throats yesterday, I now have a sweet .002" throat over groove diameter and can't wait to see how she performs.

[Bad Ass Wallace]

https://i.imgur.com/KU0yt5k.jpg

The most accurate way!

[oldhenry]

I wrap a .002 feeler gauge around the slug, measure with my Mitutoyo. I deduct .004 & have the answer.

[Alstep]

The above answers are good, and I can only add what works for me. Life long machinist/mechanic with a good feel for micrometers here. I can slowly spin a cast bullet in my mikes as I slowly close the spindle and "feel" a good measurement. I have checked my method against the "wrapping" method and get accurate measurements with my method...

This method works well for me too. The "feel" is skill only acquired with time & experience in the shop.

[alfadan]

Just for kicks you can use a ground v-block and a height gauge calibrated with a pin gauge. :groner:

[W.R.Buchanan]

Measure the actual bore dia with a gage pin. .303 ? Measure groves with caliper, you will be in one grove and one land. .308= grooves are .005 deep. so .308+.005 = .313 which is exactly what mine is.

Randy

[GregLaROCHE]

I have a NOE boolit sizer and a range of inserts. I try the slug in the smaller size working my way up until the boolit passes through. It works like a go, no go gauge.

[M-Tecs]

Just for kicks you can use a ground v-block and a height gauge calibrated with a pin gauge. :groner:

You have a 108 degree v-block? That's rarer than 108 v-mics.

Good discussion here http://www.texas-mac.com/Measuring_Groove_Diameters_of_Odd_Groove_Bores.htm l

[alfadan]

You have a 108 degree v-block? That's rarer than 108 v-mics.

Good discussion here http://www.texas-mac.com/Measuring_Groove_Diameters_of_Odd_Groove_Bores.htm l

I thought a 90* v block would work. May not be groove center-to-center but the depth of the grooves would "practically" be equal across the width of the groove. Good enough for what we're doing I suppose but I'm not a professional machinist, or even a good one lol.