Icon Logo Gun Mart

Reloading: An Even ‘Holier’ Consideration!

Reloading: An Even ‘Holier’ Consideration!

As a self-confessed ammo anorak, I spend time on the interweb searching for quality research papers on my pet subject. A multitude of productive sources include declassified documents from various elements of the U.S. Military, including the American Department of the Army for Research, Development and Acquisition Library in Washington. The later, more technical material from the U.S. Army Research Laboratory at Aberdeen Proving Ground (APG) in Maryland, as well as the Close Combat Armaments Center, Picatinny Arsenal, New Jersey.

Which leads me to the issue of terminology. I think G B Shaw got it right - (sic) “two nations divided by a common language”. For some years I’ve ignored papers that made reference to a spit-hole’, especially after a quick Google revealed some VERY strange images! Silly me. The U.S. Military, including John J Ritter of Aberdeen Proving Ground, uses the term to describe a cartridge flash hole. So here we are again, a year or so later and with more information on the topic of flash (spit) holes, thanks to John Ritter.

A QUICK REPRISE

A flash hole allows the flame and pressure wave from the detonated primer to penetrate the propellant charge. The diameter needs to be small enough to stop the propellant charge from migrating into the primer cavity and large enough to prevent back pressure from rupturing the primer cup or blowing it to shreds. Standard SAAMI, CIP and case manufacturers data gives little clues as to the most desirable dimensions. Various web forums and sites refer to SAAMI dimensions but I’m not convinced, the nearest to a consensus indicating a range of .078” to .082”. Some unattributed drawings quote a nominal industry ‘standard’ diameter of .080” with a tolerance of +.004”, -.000”. There are also ‘Match’ cases, including Lapua PPC, BR, and 6.5x47 Lapua, which are produced with flash holes of .060” nominal diameter.

Additionally, some other European brass has flash hole diameters in the range of .063” to .067”. Oh yes, there’s also the unique (to UK S1 shooters) flash hole of the .50 BMG. My last resort was to collect and measure as many sample cases as possible. Indeed, my Lapua BMG brass measures .138” to.140”. If you’re buying uniforming tools it therefore makes sense to take some prior measurements!

 

PRIMED BY PICATINNY

Ritter’s work was in part provoked by an earlier Picatinny Arsenal study, “7.62-mm PRIMER/ PROPELLANT INTERFACE STUDY” by Mahmoud David Ahmad, into delayed ignition issues with M34 primers in pre-1993 Lake City Army Ammunition Plant (LCAAP) M80 ball ammo, the results of the work were illustrated by ignition and pressure timing curves and the issues traced in part to the primer sensitizing compound, tetracene, as well as to cartridge construction anomalies. Whilst these nominal hang-fire (0.3 to 0.4 millisecond) primer delays had been tolerable in gas-operated weapons, they had serious implications on the timing functions of the M134 electric minigun.

The work went on to compare performance with crimped and un-crimped rounds, variations in bullet seating depth and changes from the standard WC846 ball propellant. One of the notable conclusions was the intimate relationship between primer detonation effects and the propellant design – a proposed change to a flash suppressed version of the M80 propellant charge, WC846FS was the outcome. It had a faster burning rate, with similar density but the changed chemistry gave much more reliable primer/propellant ignition interaction. The pressure/time curves and spikes recorded between the new and old propellant designs were significantly different. It partly explains why ‘surplus’ canister WC846 is now readily available to the American handloader!

 

SMALL FLASH HOLE, BIG PRESSURE

As a prelude to his new research, Ritter had also investigated primer timing and pressure issues in his previous work with #34 primers in 7.62 M80 ball:- “Spit-Hole Effects on the Ballistics of a 7.62-mm Cartridge”. Here he was using the WC846 based M80 cartridges as the default, with M80 ‘A’ variants using the WC846FS. This was his first published work with the use of a reduced flash hole diameter, down from .078” to .055”, equating to a 50% reduction in area. In the ‘primer-only’ evaluations he recorded a 20 fold increase in primer pocket pressure from the reduced flash hole and concluded that this was potentially disruptive.

story continues below...

When the experiment was repeated using fully assembled cartridges, the samples with the reduced flash hole produced a 350% increase in primer pocket pressure over those with the standard flash hole. In each test, the bullets in rounds employing the reduced flash hole diameter reached the engraving point faster than in the standard rounds, pointing to an accelerated deflagration profile. Since the ‘speed’ of the propellant was the same, it has to be concluded that the increased primer pressure spike achieve a faster breakdown of the ball powder retardants and initiated deflagration throughout the charge in a shorter time. Interestingly, whilst muzzle velocities were almost the same, the SD for the rounds with the reduced flash hole reduced by an amazing 30%. It seems that the Palma Match principle is a good one! Again, his tests revealed ignition inconsistencies with the ‘standard’ WC 846 propellant.

 

AN EVEN ‘HOLIER’ CONSIDERATION!

In this latest work, “Influence of Berdan and Boxer Primer Spit-Hole Diameter on 7.62-mm Cartridge Performance” he embraced the concept of Berdan flash holes. Here we have the combined performance of two of them to consider, from both a dynamic and dimensional point of view. He was again working with the 7.62mm M80 military cartridge. He used un-punched Lake City year 12 contract brass to simulate the Berdan effect, drilling two slightly offset holes, each of .055” diameter. The sum hole area being identical to that of a single ‘standard’ 7.62mm LC Boxer of .078” diameter – namely .0048 square inches. In a move not unlike my original experiments, he then produced a third batch with an oversize single flash hole of .110” diameter or .0095 square inches – approx twice the area of those in the other two batches.

 

TEST PROCESS

The three test cartridge designs were all fitted with No. 34 Boxer primers (LCAAP NATO Spec #34) from the same production batch (LC- 08E720-252). Care was taken to ensure that none of the three anvil legs obscured the two ‘Berdan’ flash holes. Projectiles and propellant were from single batches and reflected the then service recipe which by now used WC846FS. The size of each batch was surprisingly small, just eight rounds. It is interesting to compare these results with those from his earlier work.

Here the variations in pressure and performance were marginal. However, Ritter did record that the slight difference noted showed that “the Berdan style spit-hole produces pressure sooner in the IB cycle, but that pressure has a lower pressurization rate (more gradual slope) and a lower peak pressure than the (standard) M80 (49.8 ksi versus 50.6 ksi). All of this translates into a slightly diminished muzzle velocity. If there is one area that the Berdan-style primer may outperform the standard M80, it is with its consistency. The standard deviation of both the muzzle velocity and peak pressure was lower in the Berdan. However, none of the configurations explored had particularly bad standard deviations.”

 

INTIMATELY LINKED

These experiments seem to illustrate that the ‘standard’ flash hole diameter is a safe, practical dimension, fit for purpose; and that progressive increases in the surface area have an increasingly deleterious effect on cartridge performance, whilst progressive reductions in surface area cause increased pressure and accelerated deflagration for a given type and size of charge. Although not a commercially viable proposition, the tests also hint that the ‘two hole’ Berdan principle can improve regularity and reduce performance SD. Of equal interest is the close relationship between these changes and the behaviours of particular propellants.

 

CREDITS:-

Influence of Berdan and Boxer Primer Spit-Hole Diameter on 7.62-mm Cartridge Performance, John J. Ritter. Weapons and Materials Research Directorate, ARL, Aberdeen Proving Ground, MD 21005-5066. Unclassified doc. ARL-TR-6968 June 2014 Spit-Hole Effects on the Ballistics of a 7.62-mm Cartridge, John J. Ritter. Weapons and Materials Research Directorate, ARL, Aberdeen Proving Ground, MD 21005-5066. Unclassified doc. ARL-TR-6785 February 2014

7.62-mm PRIMER/PROPELLANT INTERFACE STUDY, Mahmoud David Ahmad. U.S. Army Research, Development and Engineering Center. Close Combat Armaments Center, Picatinny Arsenal, New Jersey. Unclassified doc. ARCCD-TR-97010 March 1998

57 Comments

  • metronidazole 400mg ca <a href="https://augmentiln.com/">augmentin 1000mg us</a> cost glucophage 1000mg

    Default profile image
    Sspyyz
    10 Aug 2022 at 05:07 PM
  • cheap cialis <a href="https://sildenedpill.com/">viagra next day</a> viagra mail order

    Default profile image
    Ztwyyj
    08 Aug 2022 at 04:27 AM
  • ondansetron 8mg without prescription propecia cheap

    Default profile image
    Vxbezl
    05 Aug 2022 at 02:34 AM
  • cost zantac 300mg <a href="https://zantasp.com/">zantac 150mg cheap</a> tamsulosin online order

    Default profile image
    Kkzlus
    03 Aug 2022 at 08:04 PM
  • buy cialis 40mg for sale <a href="https://tadalcialsl.com/">cialis 5mg pill</a> avodart online order

    Default profile image
    Cmregj
    02 Aug 2022 at 01:22 PM
  • esomeprazole 40mg price <a href="https://sidenafilppl.com/">sildenafil 25 mg</a> cialis tadalafil 40mg

    Default profile image
    Tmqdsw
    01 Aug 2022 at 06:25 AM
  • order sildalis online <a href="https://estracpl.com/">estradiol 1mg uk</a> purchase losartan pills

    Default profile image
    Pxvjya
    30 Jul 2022 at 11:03 PM
  • isotretinoin 20mg ca <a href="https://aurograpl.com/">purchase aurogra for sale</a> buy aurogra 100mg without prescription

    Default profile image
    Vdjbkh
    29 Jul 2022 at 11:38 AM
  • buy sildenafil 150mg generic <a href="https://prednisols.com/">cost deltasone</a> buy deltasone 40mg for sale

    Default profile image
    Fpcgnj
    28 Jul 2022 at 04:12 AM
  • methotrexate over the counter <a href="https://warfariny.com/">order generic warfarin 5mg</a> order reglan without prescription

    Default profile image
    Xfvhoe
    26 Jul 2022 at 08:30 PM
  • buy flexeril 15mg sale <a href="https://ketorolacbuy.com/">ketorolac for sale</a> clopidogrel medication

    Default profile image
    Hoobpz
    25 Jul 2022 at 09:52 AM
  • ezetimibe order online <a href="https://edbestplls.com/">best ed medication</a> motilium 10mg oral

    Default profile image
    Iyuhsn
    23 Jul 2022 at 08:57 PM
  • order viagra 50mg without prescription <a href="https://rosuvastans.com/">buy crestor 10mg sale</a> cialis dosage 40 mg

    Default profile image
    Gopdor
    21 Jul 2022 at 11:23 PM
  • buy priligy online cheap <a href="https://priligx.com/">brand dapoxetine 90mg</a> allopurinol online buy

    Default profile image
    Gslsgi
    20 Jul 2022 at 06:19 PM
  • order baricitinib sale - <a href="https://amlodipinef.com/">buy norvasc 5mg</a> lisinopril cost

    Default profile image
    Gekivb
    18 Jul 2022 at 09:49 AM
  • order generic hydroxychloroquine 400mg - <a href="https://tadalaficial.com/">order cialis 5mg pills</a> purchase cenforce

    Default profile image
    Cxzlxb
    16 Jul 2022 at 03:38 AM
  • neurontin 100mg cheap - <a href="https://dgabapentin.com/">neurontin 600mg generic</a> buy ivermectin 12mg online

    Default profile image
    Ayqong
    14 Jul 2022 at 08:42 PM
  • deltasone for sale online - <a href="https://isotretinoint.com/">order accutane 10mg generic</a> order prednisolone pill

    Default profile image
    Gpkuns
    13 Jul 2022 at 03:00 AM
  • erection pills that work - <a href="https://sildende.com/">viagra 200mg kaufen ohne rezept</a> viagra kaufen fГјr mГ¤nner

    Default profile image
    Cbsjjo
    11 Jul 2022 at 04:04 PM
  • sildenafil 100mg tablet - <a href="https://fildenapl.com/">cost sildenafil</a> sildenafil cost

    Default profile image
    Bfemzu
    10 Jul 2022 at 06:46 AM
  • flagyl 400mg oral - <a href="https://cephalexinl.com/">purchase cephalexin for sale</a> cephalexin price

    Default profile image
    Tajmth
    09 Jul 2022 at 02:23 AM
  • order finasteride 1mg for sale - <a href="https://finasterider.com/">order propecia 5mg online</a> order cipro 1000mg pill

    Default profile image
    Gepzxx
    07 Jul 2022 at 06:41 PM
  • cheap zofran 4mg - <a href="https://ondansetronr.com/">buy ondansetron 4mg generic</a> valtrex generic

    Default profile image
    Hjaqys
    05 Jul 2022 at 08:50 AM
  • how much is cialis - <a href="https://rtamsulosin.com/">order generic tamsulosin 0.4mg</a> order generic tamsulosin

    Default profile image
    Zlkrud
    02 Jul 2022 at 06:28 PM
  • purchase levofloxacin generic - <a href="https://viagplls.com/">viagra fast shipping</a> oral tadalafil 10mg

    Default profile image
    Wpmelg
    01 Jul 2022 at 04:29 AM
  • losartan cost - <a href="https://topamaxn.com/">buy topiramate 200mg sale</a> order promethazine 25mg sale

    Default profile image
    Jzxnvb
    29 Jun 2022 at 12:06 AM
  • plavix uk - <a href="https://twarfarin.com/">order coumadin 2mg pill</a> metoclopramide drug

    Default profile image
    Tivufs
    27 Jun 2022 at 07:05 AM
  • purchase flexeril for sale - <a href="https://rketorolac.com/">ketorolac for sale</a> inderal 10mg pills

    Default profile image
    Tmofba
    25 Jun 2022 at 01:36 PM
  • cost isotretinoin 40mg - <a href="https://risotretinoin.com/">order generic accutane 40mg</a> buy generic tetracycline 250mg

    Default profile image
    Uzyyax
    23 Jun 2022 at 09:01 PM
  • buy generic modafinil 200mg - <a href="https://rbudesonide.com/">budesonide pill</a> rhinocort over the counter

    Default profile image
    Raqbki
    22 Jun 2022 at 02:46 AM
  • pfizer viagra 50mg - <a href="https://rtadalafil.store/">buy cialis 10mg without prescription</a> order cialis 10mg generic

    Default profile image
    Fnmfrr
    20 Jun 2022 at 03:06 PM
  • order cenforce 100mg sale - <a href="https://xezetimibe.com/">buy zetia 10mg generic</a> motilium 10mg without prescription

    Default profile image
    Zzxsmu
    19 Jun 2022 at 05:33 AM
  • prednisone tablet - <a href="https://prednisoneix.com/">buy prednisone no prescription</a> order amoxicillin 1000mg pill

    Default profile image
    Hptjxp
    16 Jun 2022 at 01:18 AM
  • tadalafil 5mg sale - <a href="https://edtadalsfil.com/">buy tadalafil pills</a> buy viagra 50mg pills

    Default profile image
    Ragfbg
    14 Jun 2022 at 05:12 AM
  • levothyroxine over the counter - <a href="https://desloratadi.store/">order desloratadine 5mg pill</a> order hydroxychloroquine 400mg

    Default profile image
    Nlwoyu
    12 Jun 2022 at 05:33 PM
  • albuterol online - <a href="https://xdapoxetine.com/">order dapoxetine 90mg</a> buy priligy 90mg sale

    Default profile image
    Bwpzud
    11 Jun 2022 at 05:51 AM
  • buy vardenafil pills - <a href="https://vardenafilxp.com/">buy vardenafil 20mg online cheap</a> order clomid 50mg without prescription

    Default profile image
    Oqrwth
    09 Jun 2022 at 02:18 PM
  • brand lisinopril 5mg - <a href="https://omeprazolepx.com/">buy prilosec 20mg without prescription</a> order atenolol online

    Default profile image
    Jkmlgl
    08 Jun 2022 at 02:53 AM
  • buy metformin 1000mg sale - <a href="https://metforminx.store/">generic metformin 500mg</a> purchase norvasc without prescription

    Default profile image
    Kklbio
    06 Jun 2022 at 01:21 PM
  • plaquenil 200mg us - <a href="https://baricitinib.store/">buy baricitinib 2mg sale</a> order generic baricitinib 2mg

    Default profile image
    Gftliq
    05 Jun 2022 at 12:01 AM
  • lasix 40mg brand - <a href="https://furosemideg.com/">lasix 40mg oral</a> ivermectin 3mg dosage

    Default profile image
    Joohhk
    03 Jun 2022 at 08:22 AM
  • order prednisolone 10mg without prescription - <a href="https://neurontinx.store/">order gabapentin 600mg sale</a> buy sildenafil 100mg

    Default profile image
    Bmlgjk
    01 Jun 2022 at 04:28 PM
  • amoxicillin 500mg price - <a href="https://azithromycpl.com/">azithromycin generic</a> brand viagra

    Default profile image
    Fgufde
    31 May 2022 at 04:26 AM
  • prednisone 5mg over the counter - <a href="https://edpill.store/">buy ed pills fda</a> accutane 40mg sale

    Default profile image
    Vjgems
    29 May 2022 at 07:27 PM
  • buy cialis 10mg for sale - <a href="https://provigpill.store/">modafinil 100mg for sale</a> purchase modafinil pills

    Default profile image
    Euworq
    28 May 2022 at 10:16 AM
  • buy doxycycline 100mg pill - <a href="https://clomidg.store/">clomiphene 50mg pills</a> cialis 40mg oral

    Default profile image
    Gtdohg
    26 May 2022 at 01:24 PM
  • amoxil 500mg tablet - <a href="https://zithromycinc.store/">buy azithromycin 500mg online cheap</a> levitra 10mg cost

    Default profile image
    Rykutk
    23 May 2022 at 01:35 PM
  • acillin generic - <a href="https://ampicillinc.store/">buy ampicillin generic</a> cost tadalafil 20mg

    Default profile image
    Dwktcv
    21 May 2022 at 01:56 PM
  • ceftin price - <a href="https://xcialis.store/">purchase cialis online cheap</a> purchase tadalafil

    Default profile image
    Jpplvn
    20 May 2022 at 02:57 AM
  • order rhinocort sale - <a href="https://xbudesonide.quest/">buy budesonide</a> disulfiram drug

    Default profile image
    Ifumar
    18 May 2022 at 03:30 PM
  • cephalexin 500mg pills - <a href="https://xerythromycin.store/">cost erythromycin</a> erythromycin 250mg tablet

    Default profile image
    Nbkuqm
    15 May 2022 at 12:14 AM
  • bactrim drug - <a href="https://xsildenafil.store/">viagra 50mg us</a> viagra 150mg without prescription

    Default profile image
    Tzmzyc
    12 May 2022 at 04:11 PM
  • order augmentin 625mg online cheap - <a href="https://tadalcialis.store/">cialis usa</a> order tadalafil 40mg pills

    Default profile image
    Ecbvem
    10 May 2022 at 03:31 AM
  • prednisolone brand - <a href="https://cialisxb.store/">order cialis 10mg online cheap</a> cialis 5mg tablet

    Default profile image
    Cqquya
    07 May 2022 at 04:31 PM
  • viagra sildenafil 50mg - <a href="https://bestusasild.com/">buy viagra 50mg without prescription</a> over the counter viagra

    Default profile image
    Mcjghh
    03 May 2022 at 11:48 AM
  • Reloading and emission are planned for the general course for the people. The availability of https://www.essaygeeks.co.uk/buy-assignment/ is rightly followed by the students. The volume is fit for the true way for the changes. The pattern is fit for the staled items for humans.

    Default profile image
    Kasey Tatum
    07 May 2021 at 05:54 PM
  • Thank you for sharing this information, I will consider it carefully before using it!
    https://miniroyale2.com

    Default profile image
    lindatvar
    14 Apr 2020 at 10:47 AM


Arrow