Using 30-06 Blank cases

[Scharfschuetze]

Drilling out the flash hole in bottleneck cases for very light loads helps preserve the case's ability to head space properly. Apparently the detonation of the primer causes the case to jump forward and eventually push a rimless bottleneck case's shoulder back. With high pressure loads, the pressure from the powder combusting negates this, but in low pressure loads there is not enough pressure to do so and the larger flash hole helps equalize pressure between the primer pocket and the case and thus keep the shoulder from collapsing back.

A second opinion promulgates that the larger flash hole helps with uniform ignition.

My chronograph results are inconclusive over the larger flash hole for ignition uniformity, but drilling out the flash holes to save the case's shoulder datum line to head measurement is something well worth doing for cases segregated for light or squib loads.

[Ben]

Where do you get the Russian powder?

I don't think it is available anymore.
Seems like I bought mine from Hightec several yrs. ago?

[Ben]

Drilling out the flash hole in bottleneck cases for very light loads helps preserve the case's ability to head space properly. Apparently the detonation of the primer causes the case to jump forward and eventually push a rimless bottleneck case's shoulder back. With high pressure loads, the pressure from the powder combusting negates this, but in low pressure loads there is not enough pressure to do so and the larger flash hole helps equalize pressure between the primer pocket and the case and thus keep the shoulder from collapsing back.

A second opinion promulgates that the larger flash hole helps with uniform ignition.

My chronograph results are inconclusive over the larger flash hole for ignition uniformity, but drilling out the flash holes to save the case's shoulder datum line to head measurement is something well worth doing for cases segregated for light or squib loads.

Scharf,

That is a very good explanation of the " Why's " on the drilling out of the flash hole on cases intended for light loads.

Many thanks,
Ben

[C. Latch]

I don't think it is available anymore.
Seems like I bought mine from Hightec several yrs. ago?

Huh. I'd never heard of such a thing.

[Larry Gibson]

Primary reason for drilling the flash holes is to prevent the should from setting back creating cartridge headspace problems and induced misfires along with failure to extract the unfired round. The misfires and failure to extract occur in push feeds mostly when the headspace is reduced to the point the ejector pushes the case forward into the chamber not allowing the firing pin to sufficiently strike the primer and for the extractor then not to snap over the rim.

It is well proven the headspace with LR primed cases can be reduced to cause this in as little as 3 - 4 firings dependent on some variables. The extractor on a CF bolt will keep the case back against the bolt face for reliable firing and extraction. In essence the case, after 3-4 very reduced load firings, is head spacing on rim to extractor dimension instead of the should datum line. Of course this does not apply to rimmed and belted cases which should headspace sufficiently off the rim and belt.

The drilled out flash hole will improve ignition in cases of .308W or larger when used with very small amounts of fast burning powders under very light for caliber bullets. A good example is with 2.7 - 3.2 gr Bullseye under 90 - 118 gr cast bullets in .308W through '06 sized cases. The flash gets into the large and almost empty case perhaps a bit quicker but is more directly filling the entire case with the flash. That ignites the powder a bit more uniformly and reduces the "powder position" problem quite a bit.

The problem with almost all chronographs on the market is the shorter but handier screen spacing. The closer the screens are the less accurate the readings are compared to larger screen spacing. I have 3 Oehler chronographs with screen spacing of 2, 4 and 5 feet. I can also set the spacing to 10 feet. The accuracy of the larger spacing is noticeably better in that it gives much finer readings of the actual fps. Kind of like the difference in measuring with a caliper and a micrometer. With the larger screen spacing I can detect the improved ignition between cases with drilled flash holes and those with out. It is a small difference yes, but still there and beneficial to me with such loads, especially when hunting/shooting small game afield. The lessoned "powder positioning" problem is noticeable in that application.

I also have thoroughly pressure tested .308W cases with drilled flash holes (I used a large #28 drill which is about the largest diameter you'll want to use) with 311291s loaded over 4895 powder. I pushed those up to 2200+ fps and 30,000+ psi w/o any indication of pressure problems or gas leakage around the primers. The ES and SD of each test load was very consistent with identical case w/o the flash holes drilled tested at the same time. I'm not recommending cases with flash holes drilled for such use by any means. I'm just pointing out that many times what we think is happening or could happen really isn't happening.

Larry Gibson

[TXGunNut]

Thanks, guys. Very enlightening. I guess that means there's no need to do so for my light (2400) 30-30 and 32WS loads.

[Scharfschuetze]

Correct TXGunNut.

The rim prevents the case from going forward so your fire formed shoulders will stay where they're supposed to be if you're not setting them back during the sizing operation.

[Larry Gibson]

Correct TXGunNut.

The rim prevents the case from going forward so your fire formed shoulders will stay where they're supposed to be if you're not setting them back during the sizing operation.

+1.

Larry Gibson

BTW; worked a deal today at the local scrap yard for 450 lbs of lead/alloy. About 150 of it is sheet lead and the rest is dive weights which appear from initial scratch test to be WW alloy. What are you bringing down to shoot?

[Scharfschuetze]

Hey Larry,

Given the topic of this thread, you can be sure of seeing an M1 Garand in the arsenal when I get there. No blank brass, but lots of LC-67 brass with both bullets and boolits.

Rocks beware!

[Larry Gibson]

Down here.....so many to shoot.....so little time........

Larry Gibson

[0802]

Is 20.0 gr of 2400 a small enough load to drill out the flash holes with a #30 drill?


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[Larry Gibson]

What cartridge?
What weight cast bullet?
FL sized cases or fire formed?

[0802]

30-06 neck sized for a Ruger M77 and M1903, lee clone of 31141.

Sorry, this thread was linked to another post where that was listed, I forgot I was posting in a different thread.


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[Larry Gibson]

If the cases are used in both rifles and the M77 is a push feed I'd drill the flash holes. The M1903 and other controlled round feed actions will allow the case headspace to set back only as much as the rim thickness to where the extractor holds it back. There is usually enough firing pin protrusion (if within spec) that misfires don't occur. It's in push feed actions where the case headspace shortening can become a problem. I'd also suggest a Dacron filler with 16 - 20 gr 2400 under a 170 gr or lighter cast bullet in the 30-06.

[Greg S]

Just to throw this out there, I basically did the same with 6500 pcs 7.62 German blank ammo. The flash holes were tight, PPC flash hole so I found a .081 flash hole reamer from sinclair which has a small and large guide to center the reamer in the primer cup.

[0802]

Thanks, I have run this load for a while but not in high quantities. It's very good in the Ruger and the M1903 looks promising. I will try the Dacron; I've never used it.


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[Greg S]

Just to throw this out there, I basically did the same with 6500 pcs 7.62 German blank ammo. The flash holes were tight, PPC flash hole so I found a .081 flash hole reamer from sinclair which has a small and large primer cup guide to center the reamer in the primer cup?

Never mind, #30 wire gauge is .1285

[bob208]

I form 7.63 mauser out of blank brass.

[0802]

I ordered some #30 drills do open he flash holes, they are significantly larger than I expected. Please confirm I that these are right, I measured them with a micrometer, they are .127 or so.


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[bob208]

that is the correct size.