This is just an idea to measure shoulder bump. The 300 BLK has a 23 degree shoulder angle. So does a 6.8 SPC.
I thought I would purchase a 6.8 bump gage and drill it out to fit a 300 BLK fired case. I did so today and it appears everything fits. I have a Wilson gage and two made by Sheridan. This gives me a device I can measure to the nearest .001 instead of just an eye ball look see with the gages. I am an old bench rest guy (6PPC and 30BR) so shoulder bump is a big deal to me. I have carried a M16 since 1969 so I am well aware it is not a bench rest gun but with minimal shoulder bump for your chamber and single load next to the lands, accuracy can be improved enough to scare the BR guys (.223). You will not win, just get their attention. Just another tool to stay up with our brass when loading. This is an accuracy idea nothing to do with self defense or combat.
Shoulder bump
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Re: Shoulder bump
Can you provide a link to bump gauge used and describe the mods done? Diameter drill and so forth? Never heard of bump gauges or how they work, but willing to learn.
Thanks
Roger
Thanks
Roger
Carutht wrote:This is just an idea to measure shoulder bump. The 300 BLK has a 23 degree shoulder angle. So does a 6.8 SPC.
I thought I would purchase a 6.8 bump gage and drill it out to fit a 300 BLK fired case. I did so today and it appears everything fits. I have a Wilson gage and two made by Sheridan. This gives me a device I can measure to the nearest .001 instead of just an eye ball look see with the gages. I am an old bench rest guy (6PPC and 30BR) so shoulder bump is a big deal to me. I have carried a M16 since 1969 so I am well aware it is not a bench rest gun but with minimal shoulder bump for your chamber and single load next to the lands, accuracy can be improved enough to scare the BR guys (.223). You will not win, just get their attention. Just another tool to stay up with our brass when loading. This is an accuracy idea nothing to do with self defense or combat.
Re: Shoulder bump
http://www.sinclairintl.com/search/inde ... &ksubmit=y
Bump Gage Inserts are used to measure the amount of shoulder bump when setting up full length sizing dies. Our Bump Gages install in either of our comparator bodies and are machined to fit particular shoulder angles of cartridges. Rather than measuring to the datum line, these gages indicate off of the shoulder of the case to get a better, more easily assessable measurement of how much you are actually sizing your cases. We usually recommend between .001" to .002" bump for bolt action rifles and between .003" and .005" for AR15 type rifles.
I used a R drill bit to open the insert up.
Bump Gage Inserts are used to measure the amount of shoulder bump when setting up full length sizing dies. Our Bump Gages install in either of our comparator bodies and are machined to fit particular shoulder angles of cartridges. Rather than measuring to the datum line, these gages indicate off of the shoulder of the case to get a better, more easily assessable measurement of how much you are actually sizing your cases. We usually recommend between .001" to .002" bump for bolt action rifles and between .003" and .005" for AR15 type rifles.
I used a R drill bit to open the insert up.
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Re: Shoulder bump
Hornady 0.350 gage works without any drilling necessary. I've got both sets...Sinclair told me about the 6.8 gage mod...kind of WECSOG for them to recommend...couldn't bring myself to drill on such nice inserts.
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Re: Shoulder bump
Thank You guys, Will check it out.
Roger
Roger
Re: Shoulder bump
I have the Hornady set as well but was not happy with the 0.350 fit. Just by accident I saw the Sinclair insert that has the same shoulder angle as the BLK and gave it a try. The Sinclair insert is, as stated, far to pretty to put a drill bit to. I did it anyway. I like the fit but have not done any measurements with fireformed brass yet.
Re: Shoulder bump
I have been loading the 300 Blackout for a few yers now and have made cases to specifications from both 222 Rem, 223 and other similar parent cases. I happen to own several thousand new 222 Remington brass that works well albeit forming required extra steps from using my Redding form-trim-die and sizing dies which I won't elaborate on. After forming I ONT the case necks to .011"-.012" inches from nominal .013-.015 parent thickness.
I own many tools to include L.E. Wilson case gage for the 300 B.O as well as both Hornady and Sinclair bump Gage's. Hornady does not properly address either the 23° shoulder angle nor the proper case body dia at the juncture of neck to body but stops at the point of juncture. The Sinclair # 23A bump gage is specified as being for both the 6.8 SPC and the 300 BO but, the bore hole at .312" is too small for the body dia of the 300 B.O which requires .333"-.335 diam. Knowing and realizing this, I modified the improperly made and identified 23A Sinclair body hole in my lathe starting with a pilot drill of an "N" letter drill, then "O", followed by "P" and finally a "Q" drill at .334". Now the Sinclair gage 23A works for both 6.8 and 300 B.O. using the 23 degree shoulder angle as a positive stop for bump measurement.
Remember too, the Wilson gage and their fine micrometer attachment are only for "FIRED" cases and should be used and compared to each other fired case of your gun and not new brass. I use the Sinclair modified bump insert only for my newly formed virgin cases and keep the bump .001"-.002" below bump measurement for bolt guns and a slight bit more for gas platforms.
The extra step taken in modifying the Sinclair 23A bump insert pays dividends. Ted
I own many tools to include L.E. Wilson case gage for the 300 B.O as well as both Hornady and Sinclair bump Gage's. Hornady does not properly address either the 23° shoulder angle nor the proper case body dia at the juncture of neck to body but stops at the point of juncture. The Sinclair # 23A bump gage is specified as being for both the 6.8 SPC and the 300 BO but, the bore hole at .312" is too small for the body dia of the 300 B.O which requires .333"-.335 diam. Knowing and realizing this, I modified the improperly made and identified 23A Sinclair body hole in my lathe starting with a pilot drill of an "N" letter drill, then "O", followed by "P" and finally a "Q" drill at .334". Now the Sinclair gage 23A works for both 6.8 and 300 B.O. using the 23 degree shoulder angle as a positive stop for bump measurement.
Remember too, the Wilson gage and their fine micrometer attachment are only for "FIRED" cases and should be used and compared to each other fired case of your gun and not new brass. I use the Sinclair modified bump insert only for my newly formed virgin cases and keep the bump .001"-.002" below bump measurement for bolt guns and a slight bit more for gas platforms.
The extra step taken in modifying the Sinclair 23A bump insert pays dividends. Ted
Re: Shoulder bump
Curious to why you chose .334"/max neck diameter, instead of .351"/datum diameter.Tedbytes wrote: ↑Tue Jun 18, 2019 10:06 am I have been loading the 300 Blackout for a few yers now and have made cases to specifications from both 222 Rem, 223 and other similar parent cases. I happen to own several thousand new 222 Remington brass that works well albeit forming required extra steps from using my Redding form-trim-die and sizing dies which I won't elaborate on. After forming I ONT the case necks to .011"-.012" inches from nominal .013-.015 parent thickness.
I own many tools to include L.E. Wilson case gage for the 300 B.O as well as both Hornady and Sinclair bump Gage's. Hornady does not properly address either the 23° shoulder angle nor the proper case body dia at the juncture of neck to body but stops at the point of juncture. The Sinclair # 23A bump gage is specified as being for both the 6.8 SPC and the 300 BO but, the bore hole at .312" is too small for the body dia of the 300 B.O which requires .333"-.335 diam. Knowing and realizing this, I modified the improperly made and identified 23A Sinclair body hole in my lathe starting with a pilot drill of an "N" letter drill, then "O", followed by "P" and finally a "Q" drill at .334". Now the Sinclair gage 23A works for both 6.8 and 300 B.O. using the 23 degree shoulder angle as a positive stop for bump measurement.
Remember too, the Wilson gage and their fine micrometer attachment are only for "FIRED" cases and should be used and compared to each other fired case of your gun and not new brass. I use the Sinclair modified bump insert only for my newly formed virgin cases and keep the bump .001"-.002" below bump measurement for bolt guns and a slight bit more for gas platforms.
The extra step taken in modifying the Sinclair 23A bump insert pays dividends. Ted
300 Blackout, not just for sub-sonics.
Re: Shoulder bump
Yes, please do. Inquiring minds and all thatdellet wrote: ↑Tue Jun 18, 2019 10:48 amCurious to why you chose .334"/max neck diameter, instead of .351"/datum diameter.Tedbytes wrote: ↑Tue Jun 18, 2019 10:06 am I have been loading the 300 Blackout for a few yers now and have made cases to specifications from both 222 Rem, 223 and other similar parent cases. I happen to own several thousand new 222 Remington brass that works well albeit forming required extra steps from using my Redding form-trim-die and sizing dies which I won't elaborate on. After forming I ONT the case necks to .011"-.012" inches from nominal .013-.015 parent thickness.
I own many tools to include L.E. Wilson case gage for the 300 B.O as well as both Hornady and Sinclair bump Gage's. Hornady does not properly address either the 23° shoulder angle nor the proper case body dia at the juncture of neck to body but stops at the point of juncture. The Sinclair # 23A bump gage is specified as being for both the 6.8 SPC and the 300 BO but, the bore hole at .312" is too small for the body dia of the 300 B.O which requires .333"-.335 diam. Knowing and realizing this, I modified the improperly made and identified 23A Sinclair body hole in my lathe starting with a pilot drill of an "N" letter drill, then "O", followed by "P" and finally a "Q" drill at .334". Now the Sinclair gage 23A works for both 6.8 and 300 B.O. using the 23 degree shoulder angle as a positive stop for bump measurement.
Remember too, the Wilson gage and their fine micrometer attachment are only for "FIRED" cases and should be used and compared to each other fired case of your gun and not new brass. I use the Sinclair modified bump insert only for my newly formed virgin cases and keep the bump .001"-.002" below bump measurement for bolt guns and a slight bit more for gas platforms.
The extra step taken in modifying the Sinclair 23A bump insert pays dividends. Ted
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Re: Shoulder bump
I use the 350 gage as well with about .003 set back on the die, although I'm sure that could be reduced even in an AR. The shoulder is so slight.bronco_buster wrote: ↑Wed Feb 05, 2014 1:06 am Hornady 0.350 gage works without any drilling necessary. I've got both sets...Sinclair told me about the 6.8 gage mod...kind of WECSOG for them to recommend...couldn't bring myself to drill on such nice inserts.
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