(SANITIZED)PROGRESS REPORT NO. 39

• Document Type: CREST
• Collection: General CIA Records
• Document Number (FOIA) /ESDN (CREST): CIA-RDP78-03642A001500010035-6
• Release Decision: RIPPUB
• Original Classification: S
• Document Page Count: 3
• Document Creation Date: December 27, 2016
• Document Release Date: September 17, 2012
• Sequence Number: 35
• Publication Date: November 12, 1957
• Content Type: MISC

Declassified in Part - Sanitized Copy Approved for Release 2012/09/17: CIA-RDP78-03642A001500010035-6
,
25X1
3440 SOUTH STATE STREET
November 12, 1957
Dear Andy:
Enclosed please find two copies of Progress Report No. 39 on
Project No. A-077 covering the month of October, 1957.
As yet we do not have a record of the costs incurred during
October. Therefore, this information will be given you in our
next letter.
2 encls.
RWB/es
2oAR.
Sincerely yours,
Assistant Manager
OF SERVICE THROUGH RESEARCH
25X1
igt,e)61 L, 4
/t/p9)25X1
1936-1956
Declassified in Part - Sanitized Copy Approved for Release 2012/09/17: CIA-RDP78-03642A001500010035-6
Declassified in Part - Sanitized Copy Approved for Release 2012/09/17: CIA-RDP78-03642A001500010035-6
Progress Report NO. 39
C0r
I. INTRODUCTION
This report covers work done on Project No. A-077 during
October, 1957. Investigation of reduction of blast by muzzle attachments
was continued, high speed motion pictures were taken of emerging gas,
and data were assembled for the design
II. PROJECT WORK
Sound pressure data were obtained for a wide range of muzzle
attachment parameters. No significant correlation was found between flow
resistance and blast reduction, possibly due to the great difference in
pressures involved. Better correlation may be obtained for self-noise when
the blast is reduced by other means. This will be investigated when our
new facilities are completed.
Results of tests of various muzzle attachments indicate that
Comparisons of velocity, blast pressure, and wave shape were
made between
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Declassified in Part - Sanitized Copy Approved for Release 2012/09/17: CIA-RDP78-03642A001500010035-6
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Declassified in Part - Sanitized Copy Approved for Release 2012/09/17: CIA-RDP78-03642A001500010036
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H, igh speed motion pictures were made of hot gases and bullets emerging
. Measurements on successive
frames verified the timing of events, as previously determined from
oscillographic pictures.
Preliminary sketches have been made for the design of a silenced
45 cal. rifle.
III. FUTURE WORK
A few more high speed motion pictures will be made with modified
lighting arrangements in an effort to resolve the uncertainty in distinguishing
between blast and outlet noise. Tests will be made on No. 16A with barrel
holes partly closed to determine the minimum number of holes and the most
effective disposition of holes for the new design. The effect of eccentricity
of the cylinder will also be investigated.
IV. NOTEBOOKS
Data for this report are contained ix Notebook No. C-7229.
V. CONTRIBUTING PERSONNEL
25X1
Declassified in Part - Sanitized Copy Approved for Release 2012/09/17: CIA-RDP78-03642A001500010035-6
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