Enlarging a Flashhole

[Larry Gibson]

maybe a stupid question

how much can i enlarge a flashole in a 45-70 Brass for Black Powder use

at this time i use a 2,5 mm / 3/32 inch hole
is a larger hole say 3,2 mm / 1/8 recommendable or dangerous

thx for reply

Klaus

Regards the OPs question Spence Wolf found the old original mercuric boxer primers used in BP 45-70 loads were very strong (flame strength and duration), as strong as the strongest of our magnum primers of today. He relates this in his very fine book; Loading Cartridges For The Original .45-70 Springfield Rifle And Carbine. Spence also recommends the use of the Federal 215 Magnum LR Primer be used, especially with compressed BP loads. Spence recommends a #41 (.096") or a 3/32" drill be used to open the flash hole. I have done this now for many years with the 45-70 cases I load with BP. I have found no other method to give as good internal ballistics or accuracy when the BP is compressed.

As to drilling out flash holes in rimless case that headspace on the shoulder to prevent the case shoulder setting back and causing headspace problems (misfires and failure to extract) when squib/gallery/cat's sneeze loads are used; testing has consistently proven if there is insufficient psi for the case to expand and grip the chamber walls the power of the primer explosion can set the shoulder back. Over several firings with such loads the case's shoulder will set back far enough to cause misfires and extraction difficulties. This has been proven numerous times by several different individuals.

There are two real benefits to using cases with drilled flash holes if such light squib/gallery/cat's sneeze loads are used; The first is the larger flash hole allows the flash to immediately enter the case interior and does not build pressure in the primer pocket. Thus the case is not pushed forward with the attendant shoulder set back. Well fire formed cases with the flash holes drilled can be fired many, many times w/o any shoulder set back. The second benefit is the emergence of the primer flash into the case interior. With the majority of the flash entering the case at once it better fills the entire case to better ignite the small charges of powder. This is especially beneficial in cases of .300 Savage capacity and larger with the small charges of very fast burning powder normally used in such loads. The flash getting into the case as quick as possible and filling the entire case with flash promotes sure ignition of the small powder charges. It thus negates a great amount of "powder position" problems with when such small charges are used.

Of course headspace problems do not develop with rimmed cases as they headspaced on the rim, not the shoulder. If you repeatedly fire such loads in well fire formed rimmed cases you will probably see a small amount of primer back out after a few firings if the flash holes are not drilled out. This is from the shoulder being set back allowing the rim to bump up against the barrel. Even though there may be a small amount of primer back out the rimmed cases are still properly headspaced and the extraction should not be a problem.

With controlled round feed bolts the same pretty much happens as with rimed cases. The rimless case will also be pushed forward setting the shoulder back if the flash holes are not drilled with such loads. However the rim can only move as far forward as the extractor will allow it. There probably will be a bit of primer set back. Thus with normal firing pin protrusion there isn't a misfire problem and since the rim slips up under the extractor during feeding there shouldn't be any extraction problems.

It's when the squib/gallery/cat's sneeze loads are used with rimless cases in push feed actions that the problem of case headspace shortening develops. The case is constantly under pressure from the ejector pushing it forward in the chamber. If the flash hole is not drilled the primer explosion pushes the cases further and sets the shoulder back After several firings the case in chamber is pushed further and further into the chamber as the shoulder sets back from repeated firings. At some point the firing pin can not effectively crush the primer and a misfire will occur. also the extractor in the bolt may not be able to snap over the rim and extraction may be a problem.

The solution is to drill the flash holes out with a #31 - #28 drill. The #28 is the largest size that will still allow the anvil feet to have something to rest on so the primer compound will be crushed and ignited on it by the firing pin. While I normally keep some cases just for these types of squib/gallery/cat's sneeze loads are used for my push feed actions I have also found the benefit of better internal ballistics and less powder position sensitivity to be such that I also have some rimmed cases (303 and 7.62x54R) with flash holes drilled.

If some worry about the psi increasing I have measured the psi (M43 Oehler) in comparative tests with and with out the flash holes drilled using top end cast bullet loads with 311291s over 4895 powder in the .308W and the 30-06 (2200 and 1950 fps). I found no increase in the average psi and only a very slightly faster rise to peak psi in the cases with drilled flash holes. I've thus been using the cases for both squib/gallery/cat's sneeze loads, intermediate cast bullet loads and normal top end cast bullet loads w/o any problems. With top end loads the internal ballistics are almost always a bit better but accuracy remains pretty much the same.

And no, I am not saying the cases with drilled out flash holes are safe with top end higher pressure jacketed bullet loads because I do not know as I've not tested them for that. I have no real need nor desire to either. However for squib/gallery/cat's sneeze loads the use of cases with drilled flash holes is worth the effort.

Larry Gibson

[Klaus]

thx a lot for all your replies

in time between i have use this Cases with enlarged Flasholes up to 1/8 or 3,2 mm
with 63 FFFg Sporting Powder / 530 grs Postel Bullet and found no advantage on one side but also no hints in higher pressure on the other side
the Caps are not flatten more as with flasholes like .093 or with the factory hole.
Unfortunately i did not take pics but i catch up on this.

keep you informed

regards
Klaus

[semtav]

the business of primers is almost laughable. some "experts" are crowing that magums are "best" whilst other "experts" swear that pistol primers are "best". not to mention wadding outside or inside the primer hole. yeesh. standard un-wadded federal 210's seem to work ok fer me.

That must be why My 45-90 likes Federal Magnum Pistol Match primers in it !!!!

[Klaus]

thx a lot for all your replies

in time between i have use this Cases with enlarged Flasholes up to 1/8 or 3,2 mm
with 63 FFFg Sporting Powder / 530 grs Postel Bullet and found no advantage on one side but also no hints in higher pressure on the other side
the Caps are not flatten more as with flasholes like .093 or with the factory hole.
Unfortunately i did not take pics but i catch up on this.

keep you informed

regards
Klaus

regarding my post above i have made another try with 30 Rounds loaded with Wano Sporting Powder FFg

Charge was 63 grs.
530 Postel Bullet
light crimp with the necksizing die
S&B Pistol Primers
Coffeefilter OFW Wad

I found no hints about higher pressure
pics about the flashhole and the fired primers









I have had found no advantage to enlarge the flashhole finaly but also no disadvantage
accuracy are the same ( given distance 100m )

Klaus

[ndnchf]

This is a interesting discussion. I just finished reading the Wolf 45-70 book. I'm going to try following his loading techniques exactly for use in a M1884 trapdoor. I'm also wondering if some of his techniques (including an enlarged flash hole) would benefit the 50-70. I've been shooting a M1868 trapdoor with moderate success, but not yet attained the accuracy I think it should.

[Don McDowell]

I'ld look at bullet shape, diameter and lube, fouling control, and powder charge a long long time before I even considered wrecking a case with a drill bit.

[Larry Gibson]

This is a interesting discussion. I just finished reading the Wolf 45-70 book. I'm going to try following his loading techniques exactly for use in a M1884 trapdoor. I'm also wondering if some of his techniques (including an enlarged flash hole) would benefit the 50-70. I've been shooting a M1868 trapdoor with moderate success, but not yet attained the accuracy I think it should.

Note that Wolf was "replicating" the original 45-70 service loads. His goal was not to produce the most accurate loads. If you follow Wolf's methods and techniques faithfully you will get serviceable loads for your TD. However, I found better accuracy in my original TD.by using his methods with the exceptions; I do not FL size the cases, I NS with a Lyman NS die for the 45-70. I use a custom expander in the Lee expander die that gives just .002 neck tension on the bullet. I do not size the bullets to .459 but fit them to the throat using a .4615 H&I sizer. I use a 16-1 alloy as that is what Frankford Arsenal found was best for the 500 gr bullet. I use the Rapine 460500 bullet which is more accurate at longer ranges than the Lee 405HB. I also do not crimp the case mouth but use a taper crimp die to straighten the case mouth. I seat the bullet so the front of the driving band is engraved by the leade .05". Other than that I use Wolf's techniques and they have proven to be effective.

Larry Gibson

[craig61a]

Well FWIW I currently use 1:30 alloy, an Accurate Molds 461-405 mold lubed with beeswax/lanolin/cooking oil, Blackhorn 209, with a sheet of TP on top. Federal 9 1/2 primers. I have drilled out the flash hole to .093", and with that combination I get excellent accuracy. I don't size the fired cases just reload them as the case mouths run about .460" unsized. I have a copy of Wolf's book which is a good read, probably more than you'd ever want to know about the 45-70 cartridge.

Of course that's what works for me. As usual YMMV, and it's all really a matter of experimentation... The Blackhorn is spendy, but I like that it burns clean. I only put about 50 rounds through my traps in a year.

[ndnchf]

Thanks guys, good to know. I have the Lee 405 HB mold, so I'll start with that and follow his guidance. I'll see about a saeco 1881 down the road a bit. I really like the idea of trying to duplicate (as close as possible) the original arsenal load in order to see what it can do as originally designed. I'm not after top match accuracy. I have a Shiloh and others for that. In parallel with the 45-70 work, i'd like to apply similar principles to the M1868 Springfield 50-70. But the M1868 sights are very crude compared to the M1884 Buffington and hooded blade. So I don't expect the same accuracy. But maybe I can improve it some.

[Lead pot]

This discussion has come up for many years since I got a computer and followed some of the shooting forums.
Twenty some years ago the Fed Mag primers and enlarged flash holes where the hype but the accuracy down range was not as good as what you see now from shooters using all sorts of ways to cool the primer flash down by using pistol primers paper under the primer in the primer pocket paper or even milk carton wads under the powder and swaged flash holes to a lesser diameter. I done all of these things to get the upmost accuracy from my black powder loads.
When I look at the holes on my target when I use a low heat primer and I see the clover leaf hole prints on the paper this tells me that the low heat and standard flash holes is the best I can use. I would use a case with a small pistol primer if I could get brass made this way.
WHen I see the extreme spreads over the chronograph in the low single digits and the small groups on the target I know this is working.
Like Don mentioned above, "I'ld look at bullet shape, diameter and lube, fouling control, and powder charge a long long time before I even considered wrecking a case with a drill bit. " Spend time casting your bullets from a quality mould, prepping your brass and developing the load and use that drill bit for drilling holes for something other then flash holes.

[Grapeshot]

J.S. Wolf recommended the enlargement of the flash hole in .45-70 loads to insure ignition of highly compressed loads of Black powder in WW .45/70 cases to duplicate the Frankfurt Arsenal loadings of the .500/520 grain .459 boolit. He also recommended the use of Federal or Winchester Magnum Large Rifle Primers because they had the better brisance characteristics than the other brands. When I loaded my cases with 70 grains weighed of GOEX's 2Fg I had to compress the powder with a compression die almost 0.50 inch to get my 500 grain boolit to fit in the case up past the first driving band. I was happy with my results. YMMV.

[Don McDowell]

The thing to keep in mind since the twenty some odd years ago,when buggering the flashiest in cases and using magnum primers was the thing to do, many folk have done a lot of testing, and scores shot in target matches have nearly doubled national records are broken a ns set regularly, and you never hear a peep about doing that stuff by folks that actively seek the best accuracy.

[SharpsShooter]

I believe also it's worth bearing in mind that many of the top scores are being shot by individuals using a piece of newsprint overtop of of the flash hole of a non-altered case (other than perhaps truing the flash hole)

If you must enlarge them, be sure to mark them accordingly and not mix them with any cases you use for smokeless. The result would leave a lasting impression.

SS