Editing Gerald Bull (section)

===Space Research Corporation===
{{Main|Space Research Corporation}}
{{more citations needed section|date=March 2016}}

Bull returned to his Highwater range, and transferred HARP's assets to a new company. He invoked a clause in the original contract with McGill that required them to return the range to its original natural condition. Faced with hundreds of thousands of dollars in construction costs to wind down a project that could not garner funding, McGill was left with little choice but to trade Bull for title to the Highwater equipment.<ref name="astro"/> Setting up a new company, [[Space Research Corporation]] (SRC), Bull became an international artillery consultant. Incorporated in both Quebec and [[Vermont]], a number of contracts from both the Canadian and US military research arms helped the company get started.{{citation needed|date=March 2016}}. In the late 1960s, Bull established a space program at [[Norwich University]], in Northfield, Vermont.

At SRC Bull continued the development of his high-velocity artillery, adapting the HARP smoothbore into a new "reverse rifled" design where the lands of a conventional rifling were replaced by grooves cut into the barrel to make a slightly larger gun also capable of firing existing ammunition. Normally artillery shells are sealed into the rifling by a [[driving band]] of soft metal like copper, which demands that the shell be shaped so that it balances at its widest point, where the band is located. This is not ideal for ballistics,{{citation needed|date=March 2016}} especially supersonically where a higher [[fineness ratio]] is desirable. Bull solved this problem by using an additional set of nub "fins" near the front of the shell to keep it centered in the barrel, allowing the driving band to be greatly reduced in size, and located wherever was convenient. Re-shaping the shell for better supersonic performance provided dramatically improved range and accuracy, up to double in both cases, when compared to a similar gun using older-style ammunition. He called the new shell design "Extended Range, Full Bore" (ERFB).{{sfn|Anon.|1979|p=53}}

[[file:GHN-45rear.jpg|300px|thumb|right|The GC-45 howitzer as designed and manufactured by Space Research Corporation]]
Starting in 1975, Bull designed a new gun based on the common US 155/39 [[M109 howitzer]], extending it slightly to 45 calibre through modifications that could be applied to existing weapons, calling the resulting weapon the [[GC-45 howitzer]]. Bull also purchased the [[base bleed]] technology being developed in Sweden, which allowed for further improvements in range. The gun offered ranges far in excess of even the longest-ranged heavy artillery in a gun only slightly larger than common medium-weight guns.{{sfn|Anon.|1979|p=52}}

SRC's first major sales success was the sale of 50,000 ERFB shells to Israel in 1973 for use in American-supplied artillery pieces. The Israelis had successfully used a number of 175&nbsp;mm M107 guns in the counter-battery role against its Soviet counterpart, the [[130 mm towed field gun M1954 (M-46)]], but the introduction of long range rockets fired from [[Lebanon]] outranged them. The ERFB shells extended the range of the already formidable M107 to as much as {{convert|50|km}}, allowing the guns to counter-battery even the longest range rockets. {{citation needed|date=March 2016}}

Bull was rewarded for success of this program by a Congressional bill, sponsored by Senator [[Barry Goldwater]] (R-AZ) making him retroactively eligible for a decade of American citizenship and high-level American nuclear security clearance. He was granted citizenship by an Act of Congress.<ref>{{Cite journal|last=Tina|first=Starr|date=October 2009|title=Life and Work at Space Research|journal=Vermont's Northland Journal|volume=8|issue=7|page=7}}</ref>